Sample records for catamarans

  1. Calm Water and Seakeeping Investigation for a Fast Catamaran


    Broglia, Riccardo; Bouscasse, Benjamin; Jacob, Boris; Olivieri, Angelo; Zaghi, Stefano; Stern, Frederick


    In this paper calm water and in wave research activities on a high-speed displacement catamaran performed at CNRINSEAN in collaboration with the IIHR are presented. The selected geometry is the DELFT-372 catamaran, for which a large database is in construction through a series of NICOP projects. Calm water activity was carried out for the analysis of the interference phenomena; resistance, trim and sinkage tests have been performed for both the monohull and the catamaran with several separati...

  2. Fuzzy robust attitude controller design for hydrofoil catamaran

    Institute of Scientific and Technical Information of China (English)

    Ren Junsheng; Yang Yansheng


    A robust attitude controller for hydrofoil catamaran throughout its operating envelope is proposed, based on Tagaki-Sugeno (T-S) fuzzy model. Firstly, T-S fuzzy model and robust attitude control strategy for hydrofoil catamaran is presented by use of linear matrix inequality (LMI) techniques. Secondly, a nonlinear mathematical model of hydrofoil catamaran is established, acting as the platform for further researches. The specialty in interpolation of T-S fuzzy model guarantees that feedback gain can be obtained smoothly, while boat's speed is shifting over the operating envelope. The external disturbances are also attenuated to achieve H∞ control performance, meanwhile. Finally, based on such a boat,HC200B-A1, simulation researches demonstrate the design procedures and the effectiveness of fuzzy robust attitude controller.

  3. Motion Prediction of Catamaran with a Semisubmersible Bow in Wave

    Directory of Open Access Journals (Sweden)

    Sun Hanbing


    Full Text Available Compared with standard vessels, a slender catamaran with a semi-submerged bow (SSB demonstrates superior seakeeping performance. To predict the motion of an SSB catamaran, computational fluid dynamics methods are adopted in this study and results are validated through small-scale model tests. The pitch, heave, and vertical acceleration are calculated at various wavelengths and speeds. Based on the overset grid and motion region methods, this study obtains the motion responses of an SSB catamaran in regular head waves. The results of the numerical studies are validated with the experimental data and show that the overset grid method is more accurate in predicting the motion of an SSB catamaran; the errors can be controlled within 20%. The movement data in regular waves shows that at a constant speed, the motion response initially increases and then decreases with increasing wavelength. This motion response peak is due to the encountering frequency being close to the natural frequency. Under identical sea conditions, the motion response increases with the increasing Froude number. The motion prediction results, that derive from a short-term irregular sea state, show that there is an optimal speed range that can effectively reduce the amplitude of motion.


    Directory of Open Access Journals (Sweden)

    Muhammad Iqbal


    Full Text Available The amounts of research about catamaran have generated a practical formula to simplify the calculations of catamaran resistance. Ship designer will calculate the predictions of catamaran resistance rapidly. The aim of this research is focused to search the optimal demihull form where the hull form has the lowest resistance compared to other hull form models with the same displacement. To generate the different hull form, the initial hull form (parent hull is transformed so that become some models by changing the parameter of coefficient block (Cb in range ±10% with Lwl, T, H, volume and displacement are constant. The transformed hull form are calculated their total resistance from Froude number (Fr 0,2 to 0,65 with spacing hull to length ratio (S/L 0,2 to 0,4. The results of calculation show that the optimal demihull form is Model 4 where the initial hull form Cb +5%. The model has the lowest resistance compared to other models. The comparisons of resistance Model 4 with the configurations of S/L shows that the lowest resistance is S/L 0,4, so that the optimal demihull form is Model 4 with S/L 0,4.


    Directory of Open Access Journals (Sweden)

    Amin Najafi


    Full Text Available Determination of high-speed crafts’ hydrodynamic coefficients will help to analyze the dynamics of these kinds of vessels and the factors affecting their dynamic stabilities. Also, it can be useful and effective in controlling the vessel instabilities. The main purpose of this study is to determine the coefficients of longitudinal motions of a planing catamaran with and without a hydrofoil using RANS method to evaluate the foil effects on them. Determination of hydrodynamic coefficients by experimental approach is costly, and requires meticulous laboratory equipment; therefore, utilizing numerical methods and developing a virtual laboratory seems highly efficient. In the present study, the numerical results for hydrodynamic coefficients of a high-speed craft are verified against Troesch’s (1992 experimental results. In the following, after determination of hydrodynamic coefficients of a planing catamaran with and without foil, the foil effects on its hydrodynamic coefficients are evaluated. The results indicate that most of the coefficients are frequency independent especially at high frequencies.


    Directory of Open Access Journals (Sweden)

    Parlindungan Manik


    Full Text Available The Application Of Catamaran Hullform For The Fishing Vessel accorded to the leakage of the monohullform. The existence and the using of the lively fish hold could help the fisherman to decrease theoperational cost for about 11,8% to keep the fishes. Therefore the application of sail objected to reduce thebiggest cost operation component that is the fuel consumption. Catamaranhullform design for lively fish holdtook one hullform which has the best performance. The performance aspects in this case are the hydrostatic,ship resistance, stability and seakeeping.The research about catamaran fishing vessel design for lively fishes using sail and machine as the ship moveris expected to give the information about the hullform that has a better performance than the commonlyhullform and it could be an alternative to improve the fishing vessel hullform into the modern one.Accorded to the calculation result and analysis are gained the result that showed at the velocity of 12 knotsfrom some length dimension variations of fish hold for the catamaran fishing vessel with lively fish hold,variation of length of 2,0 meters could reduced the biggest ship’s resistance for about 3,99% between theother modification hullform and the ship’s resistance of standard hullform. Otherwise, by the stability aspectof any variation condition, fish hold length dimension variation at 2,0 meters had a better stability thananother fish hold length dimension and catamaran fishing vessel which used the commonly fish hold. Theinstallation of sail at the fish hold length dimension at 2,0 meters could reduce the power operation for about48,42% better than fishing vessel that used the commonly fish hold.

  7. Numerical estimation of interactions between foils and hulls of hydrofoil catamaran; Suichu yokutsuki sodosen no sentai to suichuyoku no sogo kansho

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, K.; Ando, J.; Nakatake, K. [Kyushu University, Fukuoka (Japan)


    The hydrofoil catamaran model which is built up with the twin Wigley hulls and the tandem fore and aft set of hydrofoils is used for the numerical calculation and the experiments of this model was performed at Kyushu University. In this paper, combining with a Rankine source method, the SQCM (a simple panel method) is applied to the unsymmetrical flow problem around catamarans. And the running attitude of the model is not fixed in both the calculation and the experiments. Comparing with the experiment we show the interaction between hulls and the hydrofoils for the lift and the wave-making resistance in the high speed range. 6 refs., 11 figs.

  8. On Wavemaking Characteristics of Catamarans and Trimarans%论双体船和三体船的兴波特性

    Institute of Scientific and Technical Information of China (English)



    A method for calculating wavemaking resistance of a multihull vessel and corresponding computer program have been developed. The wavemaking characteristics of catamarans and trimarans were analysed based on theoretical calculations. The ranges of Froude numbers at which beneficial and adverse interferences occur, have been indicated and the interference mechanism been preliminarily shown as well.

  9. 高速复合水翼双体船的运动预报%Motion Prediction of a High-speed Hybrid Hydrofoil Catamaran

    Institute of Scientific and Technical Information of China (English)

    高成君; 赵峰; 赵发明; 王小川


    2.5D theory considering viscous effect for predicting the motion responses of the high-speed hybrid hydrofoil catamaran in regular wave is presented in this paper,and numerical predictions are compared with experimental results. Different ratios of lift and buoyancy are calculated. Compli-cated hydrofoils are replaced by simple foil models in calculation.It is found that the viscous effect can not be ignored in calculating longitudinal motion characteristics of high-speed catamaran and hy-brid hydrofoil catamaran.The results show that the present method can satisfactorily predict the mo-tion response characteristics, and can give improved motion prediction of high-speed hybrid hydrofoil catamaran.%基于2.5D理论,考虑粘性影响,预报了高速复合水翼双体船在规则波中的运动响应,并与试验结果进行了比较.在计算过程中,对复合水翼模型进行了简化,且计算了不同升力浮力比对运动的影响.结果反应出在计算高速双体船和水翼双体复合船型纵向运动性能时,水的粘性影响不可忽略,且计算表明计算值与试验值符合较好,文中提供的方法可提高这类高速水翼双体复合船型的运动预报精度.

  10. Método dinamométrico para avaliação da escora em barcos tipo Catamaran Dynamometric method for the evaluation of hiking in Catamaran boats

    Directory of Open Access Journals (Sweden)

    Gustavo Ricardo Schütz


    Full Text Available Este estudo tem como objetivo propor e validar um método de medição da distância de escora ("De" e do momento de escora ("Me", através do uso de plataformas de força para barcos tipo Catamaran. O novo método propõe a medição por dinamometria, com o posicionamento de plataformas de força abaixo de cada casco, e a mensuração das Forças de Reação do Solo (FRS. Com base nas equações clássicas da estática são determinadas as variáveis "De" e "Me". Para validar o método proposto, foi utilizada a validação concorrente, através da comparação com os valores obtidos por cinemetria através do sistema "Peak Motus". Para correlação entre os dois métodos optou-se pelo coeficiente de correlação intraclasse (ICC. Foram analisadas diferentes posturas em duas diferentes inclinações do barco, simulando o adernamento do barco. Os resultados encontrados apontaram alta correlação (ICC > 0,99 e pequeno erro médio (1,00% para "De" e 0,96% para "Me" entre os métodos. Com isto, o método proposto se mostrou válido e eficiente, pois mensurou as variáveis de maneira rápida e precisa e se torna importante à medida que facilita a análise e auxilia a velejadores e técnicos na tomada de decisõesThis study aimed to propose and to validate a method for the measurement of hiking distance (Hd and hiking moment (Hm in Catamaran boats, through the use of force plates. This new method proposes the measurement by dynamometry, with the positioning of a force plate below each boat hoof to measure the Ground Reaction Forces (GRF. Based on the classic static equations Hd and Hm were determined. In order to validate the method a validation of competing was carried out through the comparison with kinematic values measured through the Peak Motus system. Intraclass correlation coeficient was used. Different positions in two different inclinations of the boat, simulating the boat heeling, had been analyzed. The results showed a high correlation

  11. Method for calculating wave resistance in a catamaran by using a simple panel method; Kanbenna panel ho ni yoru katamaran no zoha teiko keisanho

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, K. [Kyushu University, Fukuoka (Japan). Faculty of Engineering


    This paper describes a method for calculating wave resistance in a catamaran by using a simple panel method. Two Wigley models were put side by side to make a catamaran, speccular images were taken on a face symmetrical in the left and right sides, and only one side (the demi-hull) was used as a region to be calculated. Considering blow-out onto the demi-hull surface and still water surface, a model was constituted, in which discrete vortices were distributed on the demi-hull camber to flow the vortices out to an infinitely distance place from the stern. A free surface condition according to double model linearization by Dawson was derived for this model in terms of numerical analysis. The Kutta`s condition is incorporated when SQCM is used concurrently with the Rankine source method, but not incorporated when not used. Calculations were performed on both conditions. Wave resistance was derived by using pressure integral on the hull surface. It is better to consider the Kutta`s condition when the distance between the demi-hulls is small. However, if the distance is large, or speed is great for the boat length resulting in less interference between the demi-hulls, there is very little difference due to the Kutta`s condition. Difference in the wave shapes causes how waves are made to vary. 11 refs., 8 figs.

  12. Voyage By Catamaran: Long-Distance Network Navigation, from Myth Logic to the Semantic Web, Can Be Effected by Infinite-Dimensional Zero-Divisor Ensembles

    CERN Document Server

    de Marrais, Robert P C


    Continuing arguments presented [1] or announced [2][3] in "Complex Systems," zero-divisor (ZD) foundations for "scale-free" networks are "decentralized": "Cowbird's Nests," one "exploded" from each box-kite, house copies of the (ZD-free) Octonions - the recursive basis for all ZD ensembles, making Nests potential waystations for alien-ensemble "infiltrators." ZD "representations" of Catastrophe Theory unfoldings engulf Jean Petitot's modeling agenda, consolidating separate analyses of Greimas's Semiotic Square [4] and Levi-Strauss's Canonical Law of Myths [5] in a unified "Semantic Webology." All of which is enabled by switching focus from the octahedral Box-Kite's triangular Sails, to its square Catamarans and their box-kite-switching "twist products."

  13. 双体船结构水下中低频辐射噪声特性研究%Characteristics of Low and Middle Frequency Underwater Noise from a Catamaran

    Institute of Scientific and Technical Information of China (English)

    薛彦卓; 李硕; 徐利刚; 庞福振


    论文较为详细地研究了双体船结构水下中低频辐射噪声特性。基于声固耦合法,建立了双体船水下中低频声辐射数值预报模型,分析了单侧片体激励、双侧片体激励等典型激励下的双体船结构水下中低频辐射声场分布,讨论了双体船水下辐射噪声的计算方法。研究表明,双体船水下声辐射与单体船相比存在一定差异,片体结构会对双体船结构水下声辐射产生影响,使其辐射声场发生改变,特别是对其近场声辐射而言,当片体间距与声波波长满足一定关系时,片体之间区域会产生驻波效应,从而使双体船水下声辐射分布发生改变;而当片体间区域不产生驻波效应时,双体船水下辐射噪声大致满足线性叠加原理。%This paper examines the characteristics of low and middle frequency underwater noise from a catamaran. Based on acoustic-structure coupling method, a noise radiation prediction model for a twin-hull craft is established. Underwater noise excited by mono-hull and double-hull is studied respectively. It is shown that the behavior of underwater noise radiation from a catamaran is quite different from a single hull ship. The sound directivity changes severely when standing wave appears in the region between twin hulls. However, if the standing wave effects do not occur between twin hulls, the principle of linear superposition is approximately satisfied.

  14. 一种高速双体船耐波性的快速预报方法%A Fast Seakeeping Prediction Method for a High Speed Catamaran Advancing in Waves

    Institute of Scientific and Technical Information of China (English)

    许勇; 董文才


    文章以三维面元法为基础,开发了一套求解高速双体船在波浪中运动时耐波性的预报程序。该程序以三维移动脉动源格林函数为边界积分方程的基本内核,并根据该函数的对称特性及双体船辐射-绕射波的基本传播特征,采用三种方法来改进耐波性预报时的计算效率。以两条刘易斯船组成的双体船为计算对象,采用该程序求解了该船的水动力及运动响应,并和试验结果及未改进方法的预报结果进行了比较。分析表明文中方法的预报结果和试验结果吻合良好,且预报精度和未改进方法预报精度相当,而计算效率可达到未改进方法的2.9~4倍。因此该程序可作为高速双体船耐波性快速预报的有效方法。%Based on the 3D surface panel method, a fast-calculating computer code is developed in the present study to predict seakeeping performances for a high speed catamaran advancing in waves. The 3D translating-pulsating source Green function is chosen as the kernel function for the boundary element integral equation. Three methods based on the symmetry of the Green function to-gether with performances of the radiation-diffraction waves are introduced in the code to improve the calculating efficiency. Validation is performed through studying hydrodynamic terms and free mo-tions of a twin Lewis-form hulls by comparing model tests or predictions of the exact method (the method without improvement). The predictions obtained by the present method show general agree-ment with the experiments and the accuracy can be kept almost the same as that obtained in the exact method. The calculating speed of the present method is about 2.9-4 times of that of the exact method in the case of CPU time test. The present solver may serve as a fast and valid tool to predict seakeeping performances of a high speed catamaran advancing at sea.

  15. Motion and Wave Load Calculation of Wave-Piercing Catamaran Using 3D Hydrodynamic Method%三维流体动力方法计算穿浪双体船的船体响应

    Institute of Scientific and Technical Information of China (English)

    郑杰; 谢伟; 李慧敏


    Accurate prediction on the wave load of wave-piercing catamaran (WPC) is a difficult job due to its complexity and high speed performance. Based on linear potential theory, a 3D hydrodynamic method was proposed to calculate the motion response and wave loads of WPC in time domain. The numerical results were analyzed on frequency domain after fast Fourier transforming, and was then compared with the experimental results in regular waves. The result indicates that the proposed hydrodynamic method can successfully predict the motion and wave load of WPC and is applicable to the wave load prediction for similar vessel.%穿浪双体船船型复杂,航速较高,要准确预报其波浪载荷比较困难,但同时对于结构设计而言义非常重要.基于线性势流理论,采用三维流体动力学方法在时域上计算了穿浪双体船的运动响应和波浪载荷,时域计算结果经过傅立叶变换,在频域上分析了其响应特征.通过与规则波中试验结果和数值计算结果进行比较分析,表明用该方法计算穿浪双体船的船体响应可以获得比较满意的结果,可应用于同类船舶的波浪载荷预报.

  16. Improvement of Longitudinal Motion Performance of High Speed Light Wave-Piercing Catamaran by Hydrofoils%高速轻型穿浪双体船纵向运动改善措施研究

    Institute of Scientific and Technical Information of China (English)

    郑义; 董文才


    The pitch and heave motion range of high speed light wave-piercing catamaran (WPC) in head sea would become much higher while wave length near the ship length. Theoretical approaches together with model test were induced to provide a longitudinal motion performance improvement for a 250 t WPC using hydrofoils. The influence of the hydrofoils parameters, such as the shape, size and mounting locations, were investigated. A comparison of numerical calculation results and test data suggests that the strip method, with hydrodynamic interactions between hydrofoil and the hull taken into account, is applicable to the longitudinal motion prediction of WPC with hydrofoils, though the calculated RAO is a little bigger which near the RAO peak value. Based on the model test data, the significant amplitude of heave and pitch of the tested model in head sea reduced 20%~30% with the hydrofoils installed.%针对在改善高速轻型穿浪双体船(WPC)迎浪中波长与船长接近时纵向运动幅度较大的缺点,采用了理论计算与模型试验相结合的方法,对250t级穿浪双体船开展了水翼改善纵向运动的理论和试验研究,分析了水翼形式、尺度和安装位置等对纵向运动的影响规律.数值计算和试验结果的比较表明,计及水翼-船体水动力干扰影响的切片理论可满足WPC加水翼后波浪中纵向运动计算的需要,但在纵向运动响应峰值处数值计算结果偏高.模型试验表明,250 t级WPC加装水翼后,迎浪纵摇和垂荡有义幅值可减少20%~30%.

  17. Adoption of catamaran fishing method for mukene (Rastrineobola argentea) in off shore waters of Lake Victoria


    Wasukira, J.W.


    This report presents information on the development of a system for commercial harvesting of Rastrineobola argentea (Mukene) in Lake Victoria. The objective of this work is to develop a system for commercial Harvesting of Mukene with: •Targeted output above 1,000 kg per working night per boat. •Target area to be off shore waters of Lake Victoria. •Drying under hygienic conditions for production of high quality poultry and animal feeds. •Supply to be continuous with predicab...

  18. Improving the Efficiency of a High Speed Catamaran Through the Replacement of the Propulsion System

    Directory of Open Access Journals (Sweden)

    German de Melo Rodriguez


    Full Text Available The high speed vessels are primarily designed for short distances services as public transport of passengers and vehicles. The range of high speed, according to the Code of high-speed vessels begins at 20 knots, which depends on the cruise speed you desire for your vessel; you will have to use the most appropriate type of propellant. In general, in the past 20 years, they have been building high-speed vessels with speeds above 33 knots, which meant installing water jet propellants coupled to powerful engines and therefore of high consumption of fuel, increasing operating costs and causing increased air pollution. Although the prices of fuel have been reduced to half, due to the sharp fall in oil prices, the consumption of fuel and the air pollution remains high at these speeds and powers used, in addition to that the reduction of the time spent on each trip is not excessive, mainly in short routes that are less than an hour . This article is about adapting a ship of high-speed service, with a maximum speed in tests of 34 knots and to reduce its operating costs (fuel, maintenance, etc. and make it economically viable; before the transformation, this vessel was operating with a service speed of 22 knots, and with a consumption per mile of 135 litters of MGO. The transformation process has consisted by: – Replacement of the two original water jet with four shaft lines with fix pitch propeller. – Replacement of the two original main engines (2 x 6500 kW = 13000 kW by four engines (4 x 1380kW = 5.520 kW. – Changing the underwater hull shape to fit the new propellers and maximize its efficiency. – Relocation of auxiliary engines, to achieve the most efficient trim. – Installation of two lateral propellers to improve maneuverability and shorten the total time of journey. After the reform and the return to service of the vessel with a service speed of over 22 knots, it has been verified that the consumption per mile is of 45 litters MGO, representing a reduction of 65% of consumption and even more reduction of emissions as the new engines comply with the latest regulations.

  19. Radiated Sound of a High-Speed Water-Jet-Propelled Transportation Vessel. (United States)

    Rudd, Alexis B; Richlen, Michael F; Stimpert, Alison K; Au, Whitlow W L


    The radiated noise from a high-speed water-jet-propelled catamaran was measured for catamaran speeds of 12, 24, and 37 kn. The radiated noise increased with catamaran speed, although the shape of the noise spectrum was similar for all speeds and measuring hydrophone depth. The spectra peaked at ~200 Hz and dropped off continuously at higher frequencies. The radiated noise was 10-20 dB lower than noise from propeller-driven ships at comparable speeds. The combination of low radiated noise and high speed could be a factor in the detection and avoidance of water-jet-propelled ships by baleen whales. PMID:26611054

  20. 77 FR 10802 - Requested Administrative Waiver of the Coastwise Trade Laws: Vessel SILVER MOON; Invitation for... (United States)


    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Maritime Administration Requested Administrative Waiver of the Coastwise Trade Laws: Vessel SILVER MOON... the vessel SILVER MOON is: Intended Commercial Use of Vessel: ``Catamaran Sailing Charters, both...

  1. Cost Earnings Data 2001 - American Samoa Longline (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2001, 25 vessels > 50 feet in overall length joined the American Samoa longline fleet, which previously had consisted of local, small catamaran-style vessels...



    Samuel Samuel; Parlindungan Manik


    Model catamarans increasingly popular as a means of transportation of goods and people that needdevelopment to find out more in the interaction prisoners on the ship hull in order to achieve stability and betterresistance. KM Jasatirta is one of ship model catamaran (double hull) which is designed to support tourism inJatiluhur Reservoir. This study aims to find out more details interaction of the total prisoners in the ship's hullKM Jasatirta with Computational Fluid Dynamics approach.Resear...

  3. Seacoaster advanced marine vehicle. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Burg, D.


    The Seacoaster combines the high efficiencies of Surface Effect Ships (SES) with simple catamaran hull construction. It has blower pressurized air cushions that support some 80-90 percent of displacement and hence the high efficiencies. However, unlike the SES, there are no expensive and high maintenance flexible seals. Each catamaran sidehull has a simple recess molded or built into its underside. Powered blowers direct pressurized air into such recesses and thereby create lifting air cushions. There are no flexible seals of any kind and there is no air cushion between the sidehulls. Extensive towed model tests were conducted that showed the viability of the invention.

  4. AMD183穿浪双体客船

    Institute of Scientific and Technical Information of China (English)

    唐志祥; 徐文珊


    This paper firstly analyzed the hi-speed passenger ship market along the coastal lines in Fujian Province in brief and then made detailed introductions to the prototype AMD 183 hi-speed wavepiecing catamaran on its hull structure, superstructure and marine equipment etc.


    Institute of Scientific and Technical Information of China (English)

    LU Xiao-ping; LI Yun; DONG Zu-shun


    According to the linear wave resistance theory, a comparison among the ship resistance for the high speed round bilge ships, the deep "Vee" vessels, the wave-piercing catamarans, and the high speed trimarans was given by using the high-speed round-bilge ship as a benchmark. And the optimal speed range of each ship form was also suggested by using the analysis of the research results.



    Aulia Widyandari; Dedy Wahyudi


    There are lot of research done to develop a patrol boat, from the modification of hull model until propulsion system equipment. For example the model ship type AMV (Advanced Marine Vehicle) was developed starting from the Catamaran, Trimaran and  Pentamaran model. Everything is aimed at obtaining the ship design that has the speed and stability. In addition to achieving high-speed vessel must be equipped with propulsion (Main Power) is great, that means the main engine dimensions, auxili...

  7. Optimal Selection of Floating Platform for Tidal Current Power Station


    Fengmei Jing; Gang Xiao; Nasir Mehmood; Liang Zhang


    With continuous development of marine engineering, more and more new structures are used in the exploring of tidal current energy. Three are there different kinds of support structures for tidal current power station, which are sea-bed mounted/gravity based system, pile mounted system and floating moored platform. Comparison with them, the floating mooring system is suit for deep water and the application of which will be widely. In this study, catamaran and semi-submersible as floating platf...

  8. Experimental Study on Hysucat Vessels

    Institute of Scientific and Technical Information of China (English)

    M.S.Seif; M.Askari


    The paper contains the results of an experimental study on a planing catamaran. The aim of this study is resistance reduction with application of foils. Experiments are performed in different conditions and the results are compared with each other. The foils are used in different configurations and it is concluded that unsuitable design may result in larger resistance. But, it is also shown that, for a good design, the resistance may be reduced considerably.

  9. Sustainable Oceanographic Vessels - Setting an Example (United States)

    van Leer, J. C.


    In response to climate change, global warming and post “peak oil” fuel scarcity, the oceanographic community should consider reducing its carbon foot print. Why should scientists operate inefficient vessels while lecturing the general public on the need to reduce CO2 emissions? We have already seen curtailment of ship schedules and ship lay-ups, due in part to rising fuel costs, following $140/barrel crude oil. When the global recession ends, upward pressure on oil prices will again commence. Who can forecast how high fuel prices may ultimately rise during the typical 25-30 year lifetime of a research vessel? Are we to curtail future work at sea when oceanic climate research is becoming ever more important? A catamaran research vessel has been designed which can be electrically propelled from by a combination of high efficiency generators, photovoltaic panels and/or sails. Sail produced power is transformed with propellers and motor/generators into electric power which is stored in battery banks. This vessel could operate as the first true hybrid oceanographic research vessel. It could even continue operations without fuel in cases of a severe fuel shortage or fueling denial. Since the power produced by any water turbine increases with the cube of the velocity flowing over its propeller, the low fluid friction and high stability of a catamaran, with reasonably slender hulls, provide an important boost to efficient hybrid operation. The author has chartered a 42’ hybrid catamaran sailboat and found it efficient and extremely easy to operate and control. A 79’ motor sailing catamaran research vessel by Lock Crowther Designs will be presented as one example of a sustainable research vessel with excellent speed and sea-keeping. A center well makes operation as a small drilling/coring ship for coastal climate investigation possible. The center well also supports a host of remote sensing and robotic gear handling capabilities.

  10. Predicting water temperatures using a deterministic model: Application on Miramichi River catchments (New Brunswick, Canada) (United States)

    Caissie, Daniel; Satish, Mysore G.; El-Jabi, Nassir


    SummaryWater temperature influences many physical, chemical and biological properties of rivers. It also influences the distribution of fish and many aquatic organisms within the river environment. Hence, a good understanding of the thermal regime of rivers is essential for effective management of fisheries and aquatic resources. This study deals with the modelling of river water temperature using a deterministic model. This model calculates the net heat flux at the water surface using meteorological conditions within the study area. The water temperature model was applied on two watercourses of different size and thermal characteristics, but within a similar meteorological region, i.e. the Little Southwest Miramichi River and Catamaran Brook (New Brunswick, Canada). Data from 1992 to 1994 were used to calibrate the model, while data from 1995 to 1999 were used for the model validation. Results showed equally good agreement between observed and predicted water temperatures during the calibration period for both rivers with a root-mean-square error (RMSE) of 1.49 °C for the Little Southwest Miramichi River compared to 1.51 °C for Catamaran brook. During the validation period, RMSEs were calculated at 1.55 °C for the Little Southwest Miramichi River and 1.61 °C for Catamaran Brook. Poorer model performances were generally observed early in the season (e.g. spring), especially for the Little Southwest Miramichi River due to the influence of snowmelt conditions, while late summer to autumn performances showed among the best results for both rivers. Late autumn performances were more variable in Catamaran Brook and presumably influenced by the groundwater, geothermal conditions and potentially riparian shading. The geothermal aspect was further investigated at Catamaran Brook (using 1998 data) and results revealed that although geothermal fluxes are present, they explained very little of the unexplained variability (<0.1 °C). Similar to previous studies, the net

  11. Wind machines. [aerodynamics of sailwing vehicles (United States)

    Lissaman, P. B. S.


    The basic elements of the air/water momentum exchange are described by the environment, the potential, the air and water subsystems, the total system, and the rule. Many of these topics have direct analogues in aerogenerator design. Aspects of optimal sail design and of waveless hulls are briefly outlined. A wind driven vehicle capable of moving directly downwind faster than the wind, is reported. The lecture is illustrated with slides and movie clips showing surfing catamarans, land and water versions of the Bauer vehicle, hang gliding, land sailing, and wind surfing.

  12. Dynamic characteristics of a WPC-comparison of transfer matrix method and FE method

    Institute of Scientific and Technical Information of China (English)

    CHEN Guo-long; NIE Wu


    To find the difference in dynamic characteristics between conventional monohull ship and wave penetrating catamaran (WPC), a WPC was taken as an object; its dynamic characteristics were computed by transfer matrix method and finite element method respectively. According to the comparison of the nature frequency results and mode shape results, the fact that FEM method is more suitable to dynamic characteristics analysis of a WPC was pointed out, special features on dynamic characteristics of WPC were given, and some beneficial suggestions are proposed to optimize the strength of a WPC in design period.

  13. Developments in skirt systems for air cushion vehicles (United States)

    Inch, Peter; Prentice, Mark E.; Lewis, Carol Jean

    The present evaluation of the development status of air-cushion vehicle (ACV) skirts emphasizes the materials employed, with a view to the formulation of materials-performance requirements for next-generation AVCs and, in particular, an 'air-cushion catamaran' surface-effect ship (SES). Attention is given to novel skirt-design features which furnish substantial savings in maintenance costs. The employment of extant test rig data and the use of CAD methods are discussed, and the features of a novel system for the direct fixing of a bow finger onto an SES structure are noted.

  14. Yachting club

    CERN Multimedia

    Yachting club


    WARNING: your C key is about to expire... Good, we hoped that would draw your attention! A gentle reminder that, following the purchase of our fast, sophisticated racing catamaran Hobie Tiger Meerkat last season, your Committee decided to create a new key to reflect this, the EC (Experienced Catamaran). Those taking a C course will be assessed during a test as to whether they will gain the C key or the C plus EC key, so need only practise hard. Those - and we are many - who possess the C key from past years need to refresh our knowledge and prove our competence to sail Meerkat effectively with the EC key. This requires a few attested outings under good wind conditions, use of the gennaker, general control. And if it’s any consolation, we (remembering the Darts and then the Mysteres, and now both SL16 and Tiger) can confirm that she is really a pussycat, and really very willing to tack if you treat her right... Plan on trying for her or indeed Catapult on Thursdays, then talk to your Committee (f.i...

  15. Influence of a conservative sleep management strategy during a solo Pacific Ocean crossing on anxiety and perceived fatigue: a case study. (United States)

    Hagin, Vincent; Gonzales, Benoît R; Candau, Robin B; Groslambert, Alain


    The aim of this case study was to determine whether a sailor's deliberate choice of a conservative strategy to manage sleep deprivation would allow him to cross the Pacific Ocean and to minimize his state of anxiety and perceived fatigue. The participant, who had more than 10 years' sailing experience in severe conditions, was tested on a small catamaran without any living quarters during a solo Pacific Ocean crossing. Estimations of sleep hours, state anxiety, and perceived fatigue were self-reported by the sailor on a daily basis using a specific questionnaire. The most important finding is that the sailor's deliberate sleep strategy, 5.4 h sleep per day (24% less than on-shore), was enough to keep his anxiety and perceived fatigue within acceptable limits and enabled him to achieve his goal, which was the first crossing of the Pacific Ocean on a catamaran of less than 6 m. In conclusion, our results suggest that the sailor observed in the present case study was able to minimize anxiety and perceived fatigue with adequate sleep to optimize his performance, security, and to achieve his goal.

  16. Yachting Club

    CERN Multimedia

    Yachting Club


    Under a cloudless sky, the YCC ran its traditional Traversée du Lac for dinghies and catamarans last Sunday. The turn-out was not good, surprisingly: do we all take longer or more frequent holidays than your Committee anticipated? Never mind, we had a final fleet of six, even with no catamarans: three Laser 1’s (now that is a popular boat and surely a wise recent purchase for the Club), and three RS’s, respectively 400, 500 and 800 (private). Winds were light, but even with a slightly delayed start, they were strong enough for Race Officer Tom Wilkins and ResQ driver Tim Hancox to fit in two complete circuits/races. In older times, that would have been one race of two circuits, but the scoring is fairer if you get a chance to recover your first start in a second heat! Adjacent is a photo (thank you Loic Le Canderff, also doing important work on ResQ) of one of the final winners, Sandrine on Laser 1, joint first with overall regatta coordinator, Sanja: yes, surprisingly, th...

  17. 世界高速车客渡船的三大格局

    Institute of Scientific and Technical Information of China (English)



    At the present, the ferries in different types have taken the majority for the shortdistance car/passenger transportation field in the world market. Furthermore, in the high-speed car/passenger ferries are seemed more attractive to the shipping companies. The existing high-speed car/passenger ferries in a fierce compelition are classified into 3 categories as catamaran high-speed ferries, monohull high-speed ferries and semi-SWATH high-speed ferries. In this paper, the author has analysed the successful reasons of the high-speed car/passenger ferries, described the main features of these ferries and also summerised the developing trend of these ferries in recent years.

  18. High Performance Marine Vessels

    CERN Document Server

    Yun, Liang


    High Performance Marine Vessels (HPMVs) range from the Fast Ferries to the latest high speed Navy Craft, including competition power boats and hydroplanes, hydrofoils, hovercraft, catamarans and other multi-hull craft. High Performance Marine Vessels covers the main concepts of HPMVs and discusses historical background, design features, services that have been successful and not so successful, and some sample data of the range of HPMVs to date. Included is a comparison of all HPMVs craft and the differences between them and descriptions of performance (hydrodynamics and aerodynamics). Readers will find a comprehensive overview of the design, development and building of HPMVs. In summary, this book: Focuses on technology at the aero-marine interface Covers the full range of high performance marine vessel concepts Explains the historical development of various HPMVs Discusses ferries, racing and pleasure craft, as well as utility and military missions High Performance Marine Vessels is an ideal book for student...


    Institute of Scientific and Technical Information of China (English)

    LI Guo-an; YE Heng-kui


    A method of three-dimensional time domain Green function satisfying linear conditions at free surface and body surface boundary was employed to analyze the wave resistance and wave profile of a displacement multi-hull ship. The wave profile induced by a moving time domain point source was compared with those by a Havelock source, and satisfactory results were obtained. The panel method based on the time domain source distribution on the ship mean wetted hull surface was used to perform the wave making com- putations for mono-hull ships, catamaran and trimaran. Reasonable results were also obtained. Using the numerical method the wave profile simulations of multi-hull ships for a given Froude number were conducted.

  20. Damage Stability Assessment of an HSC after Grounding

    DEFF Research Database (Denmark)

    Ravn, Erik Sonne; Simonsen, Bo Cerup; Baatrup, Jan;


    Currently a substantial effort is done within the International Maritime Organisation (IMO) on revision of the High Speed Craft (HSC) Code. A main issue is the extent of bottom damage and raking damage due to grounding on hard rocks and the corresponding requirements to the damage stability...... of the vessel. It has been found that high-speed craft can experience a damage length up to 100% of the ship length. It has, however, also been argued that the damage stability requirements should reflect the size and probability of the damage with a reduction of the demand for the largest damages.......In the present paper a detailed grounding and damage stability analysis is carried out for two specific HSC, a mono-hull (86 m) and a catamaran (69 m). First various grounding scenarios are considered with different values of the forward speed and ground geometry. The results indicate that 100% bottom damage...

  1. Note: Development of a small maglev-type antirolling system. (United States)

    Park, Cheol Hoon; Park, Hee Chang; Cho, Han Wook; Moon, Seok Jun; Chung, Tae Young


    Various passive and/or active antirolling devices have been used for suppressing the rolling motion of ships in the ocean. In this study, a maglev-type active mass driver (AMD) is developed for controlling the rolling motion of a shiplike structure. No friction is generated during the motion of this maglev-type AMD, as the moving mass is floated by the magnetic levitation force and displaced by the propulsion force generated by the linear motor. For verifying the feasibility of the proposed method, a small AMD having a moving mass of approximately 4.0 kg is constructed and used in a small-scale model of a catamaran. This paper presents the detailed design procedures and obtained experimental results. Our results show that the developed maglev-type AMD has the potential for use in controlling the rolling motion of ships and other oceanographic vessels. PMID:20515179

  2. Resistance and Seakeeping Numerical Performance Analyses of a Semi-Small Waterplane Area Twin Hull at Medium to High Speeds

    Institute of Scientific and Technical Information of China (English)

    Giuliano Vernengo; Dario Bruzzone


    The hydrodynamic analysis of a new semi-small waterplane area twin hull (SWATH) suitable for various applications such as small and medium size passenger ferries is presented. This may be an attractive crossover configuration resulting from the merging of two classical shapes: a conventional SWATH and a fast catamaran. The final hull design exhibits a wedge-like waterline shape with the maximum beam at the stern; the hull ends with a very narrow entrance angle, has a prominent bulbous bow typical of SWATH vessels, and features full stern to arrange waterjet propellers. Our analysis aims to perform a preliminary assessment of the hydrodynamic performance of a hull with such a complex shape both in terms of resistance of the hull in calm water and seakeeping capability in regular head waves and compare the performance with that of a conventional SWATH. The analysis is performed using a boundary element method that was preliminarily validated on a conventional SWATH vessel.

  3. Intersociety Advanced Marine Vehicles Conference and Exhibit, Arlington, VA, June 5-7, 1989, Technical Papers (United States)

    The present conference on advanced marine vehicles discusses advancements in surface-effect ship (SES) technologies, small waterplane-area twin-hull (SWATH) ship operations, advanced marine vehicle concepts, ocean systems and subsurface vehicles, air-cushion vehicle (ACV) concepts, seaplane technologies, advanced hull hydrodynamics, wing-in-ground effect (WIGE) aircraft, competition-craft aerodynamics, and marine propulsion. Attention is given to military applications of the 'NES 200' SES platform, experiences over 16 years of SWATH ship operations, hydrofoil catamarans for military and civilian applications, SES passenger ferries for the N.Y.C. metropolitan area, advanced submarine concepts, parametric studies in SWATH ship design, ACV experience in Antarctica, the CL-215 seaplane, large-scale WIGE vehicles, an ocean spacecraft-launch facility, an ACV Arctic icebreaker, and 'marinizing' methods for gas turbine engines.


    Directory of Open Access Journals (Sweden)

    Samuel Samuel


    Full Text Available Model catamarans increasingly popular as a means of transportation of goods and people that needdevelopment to find out more in the interaction prisoners on the ship hull in order to achieve stability and betterresistance. KM Jasatirta is one of ship model catamaran (double hull which is designed to support tourism inJatiluhur Reservoir. This study aims to find out more details interaction of the total prisoners in the ship's hullKM Jasatirta with Computational Fluid Dynamics approach.Research carried out several stages of manufacture of the Computational Fluid Dynamic model, simulationinput data, running simulations to converge, then analyzes the results of calculations by the methodSlenderBody, Delft Series, 98, and CFD. Analysis of the calculation includes the analysis of resistance, FroudeNumber economic , and comparative analysis of numerical calculation by the method of Computational FluidDynamics.The results of the analysis and calculation of reseach showed that the total ship resistance (Rt at 2 knots boatspeed by using the CFD method at 0.37 kN, Delft method Series'98 of 0.14 kN, while the calculation method forSlender Body 0.04 kN and a analityc calculation by the method of Millward's of 0215 kN. And based on theresults of analysis of Froude number of the most economical in terms of aspects of the ship's speed is the methodof Computational Fluid Dynamics with a value of 0094 sedangan Fn projection calculation with a quadraticfunction then the value of accurate Fn Series'98 Delft method so it can be used as a reference calculation.

  5. A Floating Ocean Energy Conversion Device and Numerical Study on Buoy Shape and Performance

    Directory of Open Access Journals (Sweden)

    Ruiyin Song


    Full Text Available Wave and current energy can be harnessed in the East China Sea and South China Sea; however, both areas are subject to high frequencies of typhoon events. To improve the safety of the ocean energy conversion device, a Floating Ocean Energy Conversion Device (FOECD with a single mooring system is proposed, which can be towed to avoid severe ocean conditions or for regular maintenance. In this paper, the structure of the FOECD is introduced, and it includes a catamaran platform, an oscillating buoy part, a current turbine blade, hydraulic energy storage and an electrical generation part. The numerical study models the large catamaran platform as a single, large buoy, while the four floating buoys were modeled simply as small buoys. Theoretical models on wave energy power capture and efficiency were established. To improve the suitability of the buoy for use in the FOECD and its power harvesting capability, a numerical simulation of the four buoy geometries was undertaken. The shape profiles examined in this paper are cylindrical, turbinate (V-shaped and U-shaped cone with cylinder, and combined cylinder-hemisphere buoys. Simulation results reveal that the suitability of a turbinate buoy is the best of the four types. Further simulation models were carried out by adjusting the tip radius of the turbinate buoy. Three performance criteria including suitability, power harvesting capability and energy capture efficiency were analyzed. It reveals that the turbinate buoy has almost the same power harvesting capabilities and energy capture efficiency, while its suitability is far better than that of a cylindrical buoy.

  6. LKB-Based Evaporation Duct Model Comparison with Buoy Data. (United States)

    Babin, Steven M.; Dockery, G. Daniel


    A wave-riding catamaran with a mast-traveling sensor package (profiling buoy) was developed to make fine-scale atmospheric measurements within the first meter above the ocean surface. These measurements are used to generate time-averaged modified refractivity (M) profiles that are then compared with those determined from four evaporation duct models based on the surface layer theory of Liu, Katsaros, and Businger (LKB). Model inputs are derived from measurements from masts on the R/V Chessie and from a tethered sea surface temperature buoy. Because electromagnetic propagation is critically dependent on the M-profile slopes, different analytical techniques are employed to compare the curvature of the model profiles with that of the profiles measured by the profiling buoy. One comparison criterion was to use the rms M slope difference between the model and a curve fit to the buoy profile data. Another analytical technique was to use the rms M difference after mean M removal between the model and the buoy profiles. Using these criteria for comparison of these models with the data seems to indicate that the model-derived profiles may be missing some phenomena in the surface layer such as wave effects. Overall, however, the shapes of the measured M profiles showed log-linear characteristics near the surface. One interesting result is that each model was better at approximating the M-profile curvature for stable than for unstable conditions.

  7. Intelligent Control for USV Based on Improved Elman Neural Network with TSK Fuzzy

    Directory of Open Access Journals (Sweden)

    Shang-Jen Chuang


    Full Text Available In recent years, based on the rising of global personal safety demand and human resource cost considerations, development of unmanned vehicles to replace manpower requirement to perform high-risk operations is increasing. In order to acquire useful resources under the marine environment, a large boat as an unmanned surface vehicle (USV was implemented. The USV is equipped with automatic navigation features and a complete substitute artificial manipulation. This USV system for exploring the marine environment has more carrying capacity and that measurement system can also be self-designed through a modular approach in accordance with the needs for various types of environmental conditions. The investigation work becomes more flexible. A catamaran hull is adopted as automatic navigation test with CompactRIO embedded system. Through GPS and direction sensor we not only can know the current location of the boat, but also can calculate the distance with a predetermined position and the angle difference immediately. In this paper, the design of automatic navigation is calculated in accordance with improved Elman neural network (ENN algorithms. Takagi-Sugeno-Kang (TSK fuzzy and improved ENN control are applied to adjust required power and steering, which allows the hull to move straight forward to a predetermined target position. The route will be free from outside influence and realize automatic navigation purpose.

  8. CERN Yachting club

    CERN Document Server

    CERN Yachting club


    Surely among the most active sports clubs within CERN, the Yachting Club has had a steadily increasing membership over a decade; it is now around 350 but new members are always welcome, especially now at the beginning of a season. Indeed, with the Lottery for places in courses which are one of our highlights, membership has jumped since mid-March. The Lottery is always heavily oversubscribed, which we like to think represents its good reputation for quality of teaching and good fun at the same time. Now those lucky new students are in contact with their teachers, will be buying wetsuits in some cases (dinghy and catamaran courses), joining us for the launch of the fleet (see calendar on website at ) and  – in many cases – learning sailing as complete beginners. Those Lottery-unlucky can still plan a fun season, with our Thursday Practice evenings, where we can almost always place everyone on a boat for an outing.   ...

  9. Yachting Club

    CERN Multimedia

    Yachting Club


      Sailing course lottery Potential learners still have a couple of days to sign up to the Lottery for places in this season’s sailing courses. Yes, it is already quite heavily oversubscribed - as every year: we must run good courses! - but the draw is completely fair so you stand as good a chance as anyone else. Among questions we have been asked is which course is least oversubscribed - and might therefore offer a better chance of a place? Probably Surprise, since you ask, but then that is also one of the most demanding, both in terms of requisite keys you already need even to sign up in the Lottery and also likelihood of passing the test. Well, one was our most expensive boat purchase ever, and she is a boat that revels in being sailed well (even while being forgiving of the rest of us). The picture alongside is a loosely connected explanation to another question we get: how did catamaran Meerkat get named? We convinced ourselves that Meerkats are friendly, sociable, fast, intell...


    CERN Multimedia



    INTERNAL RAGATTE - BEST EVER ! If you missed Internal Regatta III on Sunday 11 July, you missed one of the best we can recall! The winds were about perfect, fairly stable Bf 2 with periodic gusts higher and the resulting capsizes to keep crews concentrating. It was extremely hot but we ran the usual three heats for keelboats and a record four for dinghies, catamarans - where there was another record, surely: a total of 11 boats in that class, of which three privately owned by members. And a final record: we calculate five boats were competing in their first-ever regatta. Results on the webpage. Surprisingly for those who remember regattas of a couple of years back, only three keelboats competed, so there would have been plenty of scope for less experienced members to come along regardless and probably find themselves a place. It is also noteworthy that the keelboat winner was Andrea Messina with an - ummm, may I say - less experienced crew himself! We hope this win bodes well for his forthcoming Transl&am...

  11. A Unified Computational Method for Simulating Dynamic Behavior of Planing Vessels

    Institute of Scientific and Technical Information of China (English)

    Mohammad Saeed SEIF; Ebrahim JAHANBAKHSH; Roozbeh PANAHI; Mohammad Hossein KARIMI


    High speed planing hulls have complex hydrodynamic behaviors. The trim angle and drafts are very sensitive to speed and location of the center of gravity. Therefore, motion simulation for such vessels needs a strong coupling between rigid body motions and hydrodynamic analysis. In addition, free surface shoald be predicted with good accuracy for each time step. In this paper, velocity and pressure fields are coupled by use of the fractional step method. On the basis of in- tegration of the two-phase viscous flow induced stresses over the hull, acting loads (forces and moments) are calculated. With the strategy of boundary-fitted body-attached mesh and calculation of 6-DoF motions in each time step, time history of ship motions including displacements, speeds and accelerations are evaluated. For the demonstration of the software capabilities, circular cylinder slamming is simulated as a simple type of water slamming. Then, a high-speed planing catamaran is investigated in the case of steady forward motion. All of the results are in good concordance with experimen-tal data. The present toothed can be widely implemented in design as well as in the performance prediction of high-speed vessels.


    CERN Document Server

    Yachting Club


    TRAVERSEE DU LAC MEETS BOL D’OR It is not entire coincidence that your ever-attentive YCC Committee schedules our Traversée du Lac (dinghies, catamarans, windsurfs - although admittedly not many of the latter these last few seasons) for the same weekend as the rather larger-scale Bol d’Or: it enables our intrepid crews to practise their priority rules as Dona Bertarelli sweeps past with LadyCat and gives you something to watch should the wind drop momentarily ... The rest is history, as we say and your scribe will not repeat here the results, either of the Traversée or of the Bol - go find them on our respective Webs! But many thanks to John and Sarah Fullerton for organising this event and to Wolfgang Adam for ably skippering our new Q-boat. And a gentle reminder to us all, please, that we are fairly short of volunteers on all fronts: not merely routine maintenance, remembering to clean the boat you enjoy from time to time but also - urgently - Q-boat skippers (she&...

  13. High Resolution Marine Magnetic Survey of Shallow Water Littoral Area

    Directory of Open Access Journals (Sweden)

    Jacob Sharvit


    Full Text Available The purpose of this paper is to present a system developed for detection andaccurate mapping of ferro-metallic objects buried below the seabed in shallow waters. Thesystem comprises a precise magnetic gradiometer and navigation subsystem, both installedon a non-magnetic catamaran towed by a low-magnetic interfering boat. In addition wepresent the results of a marine survey of a near-shore area in the vicinity of Atlit, a townsituated on the Mediterranean coast of Israel, about 15 km south of Haifa. The primarypurpose of the survey was to search for a Harvard airplane that crashed into the sea in 1960.A magnetic map of the survey area (3.5 km2 on a 0.5 m grid was created revealing theanomalies at sub-meter accuracy. For each investigated target location a correspondingferro-metallic item was dug out, one of which turned to be very similar to a part of thecrashed airplane. The accuracy of location was confirmed by matching the position of theactual dug artifacts with the magnetic map within a range of ± 1 m, in a water depth of 9 m.

  14. Retrospective assessment of macrophytic communities in southern Lake Garda (Italy from in situ and MIVIS (Multispectral Infrared and Visible Imaging Spectrometer data

    Directory of Open Access Journals (Sweden)

    Claudia Giardino


    Full Text Available In situ and hyperspectral MIVIS (Multispectral Infrared and Visible Imaging Spectrometer images acquired over a period of 13 years are used to assess changes in macrophyte colonization patterns in the coastal zones of the Sirmione Peninsula in the southern part of Lake Garda (Italy. In situ data (abundance, cover density and diversity of macrophyte communities and MIVIS-derived maps of colonized substrates are analyzed by considering the variability of the main hydrological and physicochemical variables in order to indicate the main factors that explain the spatiotemporal variability of macrophyte communities. The results show a considerable modification in terms of macrophyte structural complexity and colonized areas. Almost 98% of macrophyte meadows (in particular communities with a density of over 70% are lost and subsequently replaced by moderate to extremely rare communities with density from 10% to 40%. Well-established submerged macrophytes are replaced by de-structured communities characterized by moderate to scarce density: on average lower than 30%. The study indicates that macrophyte distribution along the littoral zone of the Sirmione Peninsula is certainly linked to water transparency and water level fluctuation. The results also indicate that the worsening of eutrophication may be associated with the gradual disappearance of macrophyte meadows, but may also be accelerated by herbivorous aquatic birds grazing there. Lastly, the increasing frequency and number of catamaran tours could be considered a threat for the stability of these valuable communities.

  15. Hydroelastic responses of cross deck panel to slamming; Slamming ni taisuru cross deck panel no dansei oto ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Toyama, Y. [Mitsui Engineering and Shipbuilding Co. Ltd., Tokyo (Japan)


    An analysis and a study were performed on deformation and stress response occurring in a structure when a high-speed catamaran ship is subjected to wave slamming on the lower face of the cross deck. The study proposed a method to analyze response to water slamming, which can consider elastic effects by utilizing solution of potential flow around a flat plate having perpendicular speed distribution of a triangle form. A dynamic response simulation was performed by using this method on a problem that a flat cross deck slams wave crests of parabolic shape. As a result, the following points were made clear: the maximum bending and bending moment at the center of a span of the panel show a trend of becoming proportional to the drop speed as the curvature radius on the water surface increases, where the proportion constant shows a trend of not depending on the curvature radius of the water surface; the peak value of impact pressure is thought not to give large effect directly to the dynamic response; and the reason for the maximum bending at the span center becoming proportional to the drop speed can be explained by reduction in magnification of the dynamic response. 10 refs., 14 figs., 1 tab.

  16. New approaches to the design optimization of hydrofoils (United States)

    Beyhaghi, Pooriya; Meneghello, Gianluca; Bewley, Thomas


    Two simulation-based approaches are developed to optimize the design of hydrofoils for foiling catamarans, with the objective of maximizing efficiency (lift/drag). In the first, a simple hydrofoil model based on the vortex-lattice method is coupled with a hybrid global and local optimization algorithm that combines our Delaunay-based optimization algorithm with a Generalized Pattern Search. This optimization procedure is compared with the classical Newton-based optimization method. The accuracy of the vortex-lattice simulation of the optimized design is compared with a more accurate and computationally expensive LES-based simulation. In the second approach, the (expensive) LES model of the flow is used directly during the optimization. A modified Delaunay-based optimization algorithm is used to maximize the efficiency of the optimization, which measures a finite-time averaged approximation of the infinite-time averaged value of an ergodic and stationary process. Since the optimization algorithm takes into account the uncertainty of the finite-time averaged approximation of the infinite-time averaged statistic of interest, the total computational time of the optimization algorithm is significantly reduced. Results from the two different approaches are compared.

  17. Summary of the papers of the 95th Meeting of the West Japan Society of Naval Architects. Joint meeting of three shipbuilding societies in fall, fiscal 1997; Seibu Zosenkai dai 95 kai reikai ronbun gaiko. 1997 nendo shuki zosen sangakkai rengo koenkai

    Energy Technology Data Exchange (ETDEWEB)



    The paper summarized the papers on the following: estimation of the propulsion performance by the surface vortex lattice method using model ship flow field data; wave-making resistance calculation and performance estimation by the Rankine source method; calculation method of wave-making resistance of Catamaran and solution method of the hydrofoil problem using the convenient panel method; study of estimation of hydrodynamic forces acting on ship in maneuvering motion; study of the combined plant using generator use diesel exhaust heat; mathematical structure of the ocean container transport system; developmental OTEC plants in Indonesia. In relation to structural dynamics/strength problems, reports were made on the hull longitudinal strength theory, FEM modeling in analyses of buckling/plasticity collapse of deflection panels, etc. Further reported were a consideration of the use classification of hull use steel sheets considering fracture toughness, and changes of aspect ratios of small surface cracks emanating from a toe of corner boxing. Concerning ocean structures, there are experimental studies on vibration in water of a semi-spherical shell fixed in water, and a behavior of huge floating structures in regular waves

  18. Estimation of performance of a high-speed boat by using the Rankine source method; Kosokutei no rankinsosuho ni yoru seino suitei ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Eguchi, T. [Mitsui Engineering and Shipbuilding Co. Ltd., Tokyo (Japan)


    This paper describes estimation of performance of a high-speed boat by using the Rankine source method. An orthogonal coordinate system is considered, which uses the center of a hull as the zero point, and is made dimensionless by using the hull length. The catamaran boat or the single hull boat being the subject of the discussion is supposed to have a transom stern, and to be sailing at a constant speed in the -X direction. A governing equation and a border condition were formulated using disturbance speed potential and X-direction speed differentiation. An inverse specular image was employed as a specular image system upon considering attitude change in the high-speed boat. As to the division of hull surface, the portions protruded above the static water surface were cut off from among the panel data of boat CAD. Considering a high speed condition in which the water surface is completely separated at the transom section, the water level at the transom section was supposed to be at the same height as at the rear end of the hull. Blow-out intensity at the water surface was derived in such a way that a CAD panel of the rear end of the hull is searched and wave height agrees with the height of the transom in the Z direction. A resistance curve may be obtained easily by using a personal computer. 4 refs., 8 figs.

  19. Turbulent boundary layer over a chine. (United States)

    Panchapakesan, N. R.; Joubert, P. N.


    The flow over an edge aligned with the streamwise direction is studied as a representative of the turbulent boundary layers developing over hard chines found on the hulls of ships and catamarans. We present results of a traditional experimental investigation of this geometry in a wind tunnel with pitot tubes and hot-wires. The chine model consisted of two surfaces made of varnished fibre boards with leading edges of airfoil sections and a 90 degree corner. The boundary layer was tripped with wires close to the leading edge. The model was housed in a test section of length 6.5 m in a closed circuit wind tunnel. The experiments were conducted at a unit Reynolds number of 680,000 /m corresponding to a nominal free stream velocity of 10 m/s. The mean velocity field and the associated integral parameters obtained with pitot tube measurements are presented for different streamwise locations from 0.2 to 4.7 m from the trip wire. The flow at the two farthest locations were also studied with single and 'x' hot-wires. The secondary mean flow and the turbulence field in the corner region are described with these measurements.

  20. Archive of single-beam bathymetry data collected during USGS cruise 07CCT01 nearshore of Fort Massachusetts and within Camille Cut, West and East Ship Islands, Gulf Islands National Seashore, Mississippi, July 2007 (United States)

    DeWitt, Nancy T.; Flocks, James G.; Reynolds, B.J.; Hansen, Mark


    identifier to each cruise or field activity. For example, 07CCT01 tells us the data were collected in 2007 for the Coastal Change and Transport (CCT) study and the data were collected during the first (01) field activity for that project in that calendar year. Refer to for a detailed description of the method used to assign the field activity ID. Data were collected using a 26-foot (ft) Glacier Bay catamaran. The single-beam transducers were sled mounted on a rail attached between the catamaran hulls. Navigation was acquired using HYPACK, Inc., Hypack version 4.3a.7.1 and differentially corrected using land-based GPS stations. See the digital FACS equipment log for details about the acquisition equipment used. Raw datasets were stored digitally and processed systematically using NovAtel's Waypoint GrafNav version 7.6, SANDS version 3.7, and ESRI ArcGIS version 9.3.1. For more information on processing refer to the Equipment and Processing page.


    Directory of Open Access Journals (Sweden)

    Aulia Widyandari


    Full Text Available There are lot of research done to develop a patrol boat, from the modification of hull model until propulsion system equipment. For example the model ship type AMV (Advanced Marine Vehicle was developed starting from the Catamaran, Trimaran and  Pentamaran model. Everything is aimed at obtaining the ship design that has the speed and stability. In addition to achieving high-speed vessel must be equipped with propulsion (Main Power is great, that means the main engine dimensions, auxiliary equipments and fuel tanks is too large. Many Limitations of space on the ship's engine room trimaran vessel is the main obstacle in designing propulsion system. Beside that Patrol boat should have many missions speed, so propulsion system should be designed at that conditions.   Hybrid propulsion is a combination of Diesel Mechanical Propulsion (DMP with Diesel Electric Propulsion (DEP. DMP system is connected directly to the propeller shaft (or through a reduction-gear. DMP has provide more efficiency rate of 95%. While DEP is only able to provide efficiency by 85% - 89% is slightly lower than DMP, but the DEP offers many advantages such as simplicity and suitability in the rotational speed settings, control systems, engine power production Redundancy, Flexibility in the design of equipments layout in engine rooms, noise, vibration and fuel consumption efficiency which affects the lower pollution.   Design of Hybrid Propulsion system can be satisfied and achieved the Power requirements and optimally at all speed condition of patrol boat. Therefore the author made using modeling Maxsurf-11.12 software and carried out various optimization of the choice of main engine, propeller and system conditions for fast patrol boat cruise. 

  2. Multi-tiered sensing and data processing for monitoring ship structures

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, Charles [Los Alamos National Laboratory; Salvino, Liming [NSWCCD; Lynch, Jerome [UNIV. OF MICHIGAN; Brady, Thomas [NSWCCD


    A comprehensive structural health monitoring (SHM) system is a critical mechanism to ensure hull integrity and evaluate structural performance over the life of a ship, especially for lightweight high-speed ships. One of the most important functions of a SHM system is to provide real-time performance guidance and reduce the risk of structural damage during operations at sea. This is done by continuous feedback from onboard sensors providing measurements of seaway loads and structural responses. Applications of SHM should also include diagnostic capabilities such as identifying the presence of damage, assessing the location and extent of damage when it does occur in order to plan for future inspection and maintenance. The development of such SHM systems is extremely challenging because of the physical size of these structures, the widely varying and often extreme operational and environmental conditions associated with the missions of high performance ships, the lack of data from known damage conditions, the limited sensing that was not designed specifically for SHM, the management of the vast amounts of data, and the need for continued, real-time data processing. This paper will discuss some of these challenges and several outstanding issues that need to be addressed in the context of applying various SHM approaches to sea trials data measured on an aluminum high-speed catamaran, the HSV-2 Swift. A multi-tiered approach for sensing and data processing will be discussed as potential SHM architecture for future shipboard application. This approach will involve application of low cost and dense sensor arrays such as wireless communications in selected areas of the ship hull in addition to conventional sensors measuring global structural response of the ship. A recent wireless hull monitoring demo on FSF-I SeaFighter will be discussed as an example to show how this proposed architecture is a viable approach for long-term and real-time hull monitoring.

  3. 一种基于APDL语言的船舶波浪压力自动加载方法%An Approach to Automatically Loading Wave Pressure Using APDL in ANSYS

    Institute of Scientific and Technical Information of China (English)

    丁德勇; 郑杰; 谢伟; 胡要武; 杨龙


    针对全船结构强度直接计算中,波浪加载较为麻烦的问题,提出了一种ANSYS环境下的波浪压力自动加载的方法。该方法将三维水动力程序计算的船体表面的波浪压力经过插值算法转换到有限元结构单元上,压力数据文件读入ANSYS实现了自动加载。最后,利用该自动加载方法对一艘穿浪双体船进行加载。结果表明,该方法将波浪载荷计算和结构强度分析有机结合起来了,提高了波浪压力加载的准确性和效率。%Since wave pressure loading in the direct calculation of overall ship structural strength is a time-consuming job, an automatic loading approach in the ANSYS environment was proposed. Using this method, wave pressure on ship surface calculated by 3D hydrodynamic program was transferred to Finite Element model by interpolation algorithm. The pressure data file was read into ANSYS to fulfill the automatic loading process. The automatic approach was applied to a wave piercing catamaran as an example. The results show that the proposed approach can combine the wave load calculation with ship structural strength analysis, greatly improving accuracy and efficiency of wave pressure loading.


    Directory of Open Access Journals (Sweden)

    Parlindungan Manik


    Full Text Available Jatiluhur had the very big tourism potency so that it was required the supporting mean such as the tour ship which was better than the wooden ship. The research about the tour ship design having a catamaran hull form was expected to help the development of potencial tourism in Jatiluhur reservoir. In conducting this research, there were several research designs used those were the principle dimension, lines plan, general arrangement, hydrostatic analysis, stability analysis and ship motion analysis. Furthermore, it was used the selection of ship equipments and main engine which is based on result of motor power calculation appropriate for resistance against ship.  The result of this tourist ship design was in the form of hydrostatic analysis, general arrangement, the analysis of stability and ship motion. The resulth shown by the hydrostatic analysis was that the buoyancy located behind the midship as far as 0.469 m. In addition, the result of general arrangement indicated that this tour ship had enough rooms to store all the ship equipment and it was able to carry the passangers with the maximum capacity of twenty people. In a review analysis of stability, it was shown that the largest GZ value was 2,009 m in the ten condition in which it carried ten passangers on the left side with a consumable weight of 100%. This tour ship had a good ship motion in which the deck wetness was not occurred when the wave happened as 0,70 m with the wave heading of 90° having a value of amplitudo heave motion of 0,176 m, the pitchmotion of 1,04 °, and roll motion of 2,99 °.

  5. Inter-comparison of hydro-climatic regimes across northern catchments: Synchronicity, resistance and resilience (United States)

    Carey, S.K.; Tetzlaff, D.; Seibert, J.; Soulsby, C.; Buttle, J.; Laudon, H.; McDonnell, J.; McGuire, K.; Caissie, D.; Shanley, J.; Kennedy, M.; Devito, K.; Pomeroy, J.W.


    The higher mid-latitudes of the Northern Hemisphere are particularly sensitive to climate change as small differences in temperature determine frozen ground status, precipitation phase, and the magnitude and timing of snow accumulation and melt. An international inter-catchment comparison program, North-Watch, seeks to improve our understanding of the sensitivity of northern catchments to climate change by examining their hydrological and biogeochemical responses. The catchments are located in Sweden (Krycklan), Scotland (Mharcaidh, Girnock and Strontian), the United States (Sleepers River, Hubbard Brook and HJ Andrews) and Canada (Catamaran, Dorset and Wolf Creek). This briefing presents the initial stage of the North-Watch program, which focuses on how these catchments collect, store and release water and identify 'types' of hydro-climatic catchment response. At most sites, a 10-year data of daily precipitation, discharge and temperature were compiled and evaporation and storage were calculated. Inter-annual and seasonal patterns of hydrological processes were assessed via normalized fluxes and standard flow metrics. At the annual-scale, relations between temperature, precipitation and discharge were compared, highlighting the role of seasonality, wetness and snow/frozen ground. The seasonal pattern and synchronicity of fluxes at the monthly scale provided insight into system memory and the role of storage. We identified types of catchments that rapidly translate precipitation into runoff and others that more readily store water for delayed release. Synchronicity and variance of rainfall-runoff patterns were characterized by the coefficient of variation (cv) of monthly fluxes and correlation coefficients. Principal component analysis (PCA) revealed clustering among like catchments in terms of functioning, largely controlled by two components that (i) reflect temperature and precipitation gradients and the correlation of monthly precipitation and discharge and (ii

  6. The optimal access system for future far-offshore wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Obdam, T.S.; Rademakers, L.W.M.M.; Savenije, L.B. [ECN Wind Energy, Petten (Netherlands)


    Operation and maintenance (O and M) of offshore wind turbines is one of the main cost drivers of offshore wind energy. One of the aspects critical for an efficient and cost-effective O and M strategy is the selection of the access system which is used to transfer technicians and, optionally, small spare parts. Currently, most offshore wind farms are located close to shore, and their size is relatively small. For these farms the typical access system consists of catamaran-like workboats, which are used to transfer both technicians and small spare parts. As wind farms move further offshore this O and M concept might no longer be cost-effective. Currently, different alternative O and M concepts are being considered for the future far-offshore sites. In this paper an extensive and holistic comparison of different O and M concepts including different access system solutions is presented. This analysis has been performed using the OMCECalculator, ECN's software for advanced O and M cost modelling. Different sites have been considered, which are typical for the future offshore wind farms that will be commissioned during the next five years. The results of the performed analyses indicate that when moving further offshore harbour-based O and M strategies are no longer economical, even when helicopters are added to the mix. Looking at farm-based O and M concepts a supply vessel with a compensated access gangway offers great potential. However, the calculations also indicate that its ability to transfer small spare parts, in addition to technicians, is crucial.

  7. Application of Surface-Water Microlayer Sampler in the Hydrologic Assessment of Frog Malformations in Minnesota (United States)

    Jones, P. M.; Menheer, M. A.; Taylor, H.; Aiken, G.; Peart, D.; Thurman, E. M.; Scribner, E. A.; Weishaar, J.; Rostad, C.; Rosenberry, D.


    Since the summer of 1993, frog malformations have been reported throughout North America, including over 150 sites in 54 counties of Minnesota. Water-quality analyses of bulk water (grab) samples collected at more than 20 frog malformation sites have yet to indicate any direct relationships between water quality and frog malformation rates. However, many potential contaminants to frog egg masses, metamorphs, and adults are hydrophobic or have a strong association with floating particles that may accumulate in microlayers found on the surface of water bodies. To assess surface microlayer chemistry, a radio-controlled catamaran sampler was developed to collect hydrophobic microlayer samples using a rotating Teflon-coated drum. The drum was positioned to sit approximately 0.5 inch in the surface-water body. Samples were collected on the rotating drum, extracted off the rotating drum using a series of wiper-blades, and funneled into Teflon collection pans. A series of water samples were collected using three different techniques to determine if any relationships exist between the water quality of the surface microlayer and/or lower waters and frog malformation rates. Grab, upper-surface, and microlayer samples were collected during June, August and October 2001 at four surface-water bodies. Grab samples were collected through Teflon tubing held throughout the vertical water column, while upper-surface water samples were collected through Teflon tubing held at the water surface. Microlayer samples were collected using the designed sampler. Collected water samples were analyzed for major ions, trace elements, nutrients, total mercury, dissolved organic carbon, pesticides, hormones, isoflavones, and a series of waste-water constituents. In 2000, frog malformation rates were above 5% at two of the sites, and rates were less than 1% at the other two sites. Available results from water-quality analyses will be presented.

  8. 高速水翼船垂荡与纵摇运动模拟%Simulation of heaving and pitching motion of fast boat with hydrofoils

    Institute of Scientific and Technical Information of China (English)

    任俊生; 杨盐生


    From the angle of analyzing the forces acting on the ship, the mathematical model is established ofheaving motion and pitching motion in still water. The calculations of every parameter in the model are pre-sented, and especially the lift forces of hydrofoils are detailed. For the purpose of validating the effective-ness of the mathematical model, based on a hydrofoil catamaran, HC200B, the simulation research is car-ried out, by use of Mablab's Simulink toolbox, so that the elevations and trim angles are obtained corre-sponding to 12 velocity points and the variation of the boat's attitude at the design speed is also obtained.In comparison with the simulation results and experimental data, it is shown that both of them agree wellwith each other, especially in the vicinity of high speed, which exhibits the effectiveness of the proposedmathematical model.%从受力分析的角度,建立了垂荡和纵摇的数学模型.给出了模型中各个参数的计算方法,尤其是对水翼产生的升力进行了详细地分析.为了验证模型的有效性,基于一艘高速水翼双体船HC200B,使用Matlab的Simulink工具箱进行了仿真研究,给出了在12个航速点的上浮量和纵倾值,以及在设计航速的船体姿态.对比仿真数据和实验数据,包括高速域附近的数据,二者相符得很好,这表明了所提出的模型是合理的.

  9. CHIRP survey of the submerged harbors of King Herod's Caesarea, offshore Israel - looking for evidence of ancient disasters (United States)

    Austin, J. A.; Goodman-Tchernov, B.


    on the starboard flank of a ~8 m-long catamaran. Data acquisition was generally conducted from dawn to mid-day, when wind/wave conditions were most favorable. A dense (5-10 m average profile spacing) grid of profiles, both along-strike (spanning the entire harbor complex) and across-strike (from intermediate harbor to ~10-15 m of water), was acquired. Total track length is ~126 line-km. In certain places, multiple sub-bottom horizons can be traced and mapped; sub-seafloor penetrations up to ~ 4-5 m were occasionally achieved, particularly in deeper water. However, sub-bottom penetration is spatially variable in sand-prone sediments. Correlation difficulties relate both to uneven acoustic penetration and to the presence offshore of "kurkar" ridges, calcareous sandstone ridges paralleling the modern shoreline that represent now-submerged Pleistocene dune complexes. These ancient dunes can produce physical barriers that both alter the depositional regime as well as complicate the acoustic mapping task. Mapped horizons within the survey area will be shown, along with preliminary correlations to the stratigraphy described from previously cored sediments (e.g., interpreted "tsunamites").

  10. Monitoring Sea Level At L'Estartit, Spain (United States)

    Martinez-Benjamin, J.; Ortiz Castellon, M.; Martinez-Garcia, M.; Talaya, J.; Rodriguez Velasco, G.; Perez, B.


    Sea level is an environmental variable which is widely recognised as being important in many scientific disciplines as a control parameter for coastal dynamical processes or climate processes in the coupled atmosphere-ocean systems, as well as engineering applications. A major source of sea-level data are the national networks of coastal tide gauges, in Spain belonging to different institutions as the Instituto Geográfico Nacional (IGN), Puertos del Estado (PE), Instituto Hidrográfico de la Marina (IHM), Ports de la Generalitat, etc. Three Begur Cape experiences on radar altimeter calibration and marine geoid mapping made on 1999, 2000 and 2002 are overviewed. The marine geoid has been used to relate the coastal tide gauge data from l'Estartit harbour to off-shore altimetric data. The necessity to validate and calibrate the satellite's altimeter due to increasing needs in accuracy and long term integrity implies establishing calibration sites with enhanced ground based methods for sea level monitoring. A technical Spanish contribution to the calibration experience has been the design of GPS buoys and GPS catamaran taking in account the University of Colorado at Boulder and Senetosa/Capraia designs. Altimeter calibration is essential to obtain an absolute measure of sea level, as are knowing the instrument's drifts and bias. Specially designed tidegauges are necessary to improve the quality of altimetric data, preferably near the satellite track. Further, due to systematic differences a month instruments onboard different satellites, several in-situ calibrations are essentials to tie their systematic differences. L'Estartit tide gauge is a classical floating tide gauge set up in l'Estartit harbour (NE Spain) in 1990. It provides good quality information about the changes in the sea heights at centimetre level, that is the magnitude of the common tides in theMediterranean. In the framework of a Spanish Space Project, ref:ESP2001- 4534-PE, the instrumentation of sea

  11. A Numerical Method for Predicting Wash Waves of SES%一种计算SES船尾波(Wash wave)的数值方法

    Institute of Scientific and Technical Information of China (English)

    谢楠; Andrzej JASIONOWSKI; Dracos VASSALOS


    A numerical method is presented for predicting wash waves of Surface Effect Ships (SES)at deep waters.The wash waves of the SES are represented by the wave-making of a moving rectangular pressure distribution over the air cushion. Basing on the linear potential theory, the wash waves can be analytically expressed as integrals whose integrands oscillate with high frequency.The numerical procedure involves transformation of the integral variables,such that the integrands are monotonic for different vessel speed,shape of the pressure patch and locations of the wave to be calculated,and easy to facilitate the numerical calculation.The singularities of the integral can be also removed. Numerical results show that the present method is of high computational efficiency and with good agreement with the published results. Some results of wash waves of SES are presented and discussed.The characters of local and non-local effect parts of the wash wave of SES are discussed. Attempt is also tried to apply the present method in predicting wash wave of conversional catamaran,the comparison between the prediction and the model test measurement shows fairly good agreement.%本文提出了一种无限深水中表面效应船(Surface Effect Ship,SES)尾波(Wash wave)数值方法.SES的尾波被表达成分布在气垫上的压力在静水中航行产生的兴波波浪场.在线性势流假设下,该尾波可解析地表示为积分形式,而其被积函数带有奇性并高频振荡.文中提出了一个变换,使变换后对不同的航速,SES船形(气垫形状)和所要计算的波浪场位置尾波计算中的被积函数是单调变化,因而易于数值计算.积分中的奇性也予以去除.数值计算结果表明本文提出的数值方法具有较高的计算效率而且结果与已发表的结果吻合良好.文中给出了一些SES船尾波(Wash wave)的计算结果,并进一步分析了SES尾波(Wash wave)中的局部和非局部波浪场成分.文中还尝试使用本

  12. Immersive, hands-on, team-based geophysical education at the University of Texas Marine Geology and Geophysics Field Course (United States)

    Saustrup, S.; Gulick, S. P.; Goff, J. A.; Davis, M. B.; Duncan, D.; Reece, R.


    The University of Texas Institute for Geophysics (UTIG), part of the Jackson School of Geosciences, annually offers a unique and intensive three-week marine geology and geophysics field course during the spring/summer semester intersession. Now entering its seventh year, the course transitions students from a classroom environment through real-world, hands-on field acquisition, on to team-oriented data interpretation, culminating in a professional presentation before academic and industry employer representatives. The course is available to graduate students and select upper-division undergraduates, preparing them for direct entry into the geoscience workforce or for further academic study. Geophysical techniques used include high-resolution multichannel seismic reflection, CHIRP sub-bottom profiling, multibeam bathymetry, sidescan sonar, sediment coring, grab sampling, data processing, and laboratory analysis of sediments. Industry-standard equipment, methods, software packages, and visualization techniques are used throughout the course, putting students ahead of many of their peers in this respect. The course begins with a 3-day classroom introduction to the field area geology, geophysical methods, and computing resources used. The class then travels to the Gulf Coast for a week of hands-on field and lab work aboard two research vessels: UTIG's 22-foot, aluminum hulled Lake Itasca; and NOAA's 82-foot high-speed catamaran R/V Manta. The smaller vessel handles primarily shallow, inshore targets using multibeam bathymetry, sidescan sonar, and grab sampling. The larger vessel is used both inshore and offshore for multichannel seismic, CHIRP profiling, multibeam bathymetry, gravity coring, and vibracoring. Field areas to date have included Galveston and Port Aransas, Texas, and Grand Isle, Louisiana, with further work in Grand Isle scheduled for 2014. In the field, students work in teams of three, participating in survey design, instrument set-up, field deployment

  13. System identification and the modeling of sailing yachts (United States)

    Legursky, Katrina

    yaw. Existing aerodynamic models for sailing yachts are unsuitable for control system design as they do not include a physical description of the sails' dynamic effect on the system. A new aerodynamic model is developed and validated using the full-scale sailing data which includes sail deflection as a control input to the system. The Maximum Likelihood Estimation (MLE) algorithm is used with non-linear simulation data to successfully estimate a set of hydrodynamic derivatives for a sailing yacht. It is shown that all sailing yacht models will contain a second order mode (referred to herein as Mode 1A.S or 4B.S) which is dependent upon trimmed roll angle. For the test yacht it is concluded that for this mode when the trimmed roll angle is, roll rate and roll angle are the dominant motion variables, and for surge velocity and yaw rate dominate. This second order mode is dynamically stable for . It transitions from stability in the higher values of to instability in the region defined by. These conclusions align with other work which has also found roll angle to be a driving factor in the dynamic behavior of a tall-ship (Johnson, Miles, Lasher, & Womack, 2009). It is also shown that all linear models also contain a first order mode, (referred to herein as Mode 3A.F or 1B.F), which lies very close to the origin of the complex plane indicating a long time constant. Measured models have indicated this mode can be stable or unstable. The eigenvector analysis reveals that the mode is stable if the surge contribution is 20%. The small set of maneuvers necessary for model identification, quick OSLS estimation method, and detailed modal analysis of estimated models outlined in this work are immediately applicable to existing autonomous mono-hull sailing yachts, and could readily be adapted for use with other wind-powered vessel configurations such as wing-sails, catamarans, and tri-marans. (Abstract shortened by UMI.)

  14. 港珠澳大桥非通航孔85 m连续组合梁桥施工关键技术%Key Construction Techniques for 85 m Non-navigational Channel Con-tinuous Composite Girder Bridge of Hongkong-Zhuhai-Macao Bridge

    Institute of Scientific and Technical Information of China (English)



    港珠澳大桥浅水区非通航孔桥为11联双幅85 m连续组合梁桥,基础采用钢管复合桩,承台及墩身采用预制拼装结构,承台深埋于海床内,上部结构采用组合梁结构。桥位处地质复杂、环境恶劣,利用“小天鹅”号运架双体船搭载整体导向架系统,实现复合桩基础钢管三次定位,精确控制钢管插打;承台+底节墩身整体预制时钢筋按4个模块分别绑扎,组拼成整体后应用自动化开合模板浇筑混凝土,并采用裂纹控制技术及防腐措施;承台+底节墩身预制构件采用“小天鹅”号运架一体船运输、起吊下放进入锁口钢套箱围堰内,通过复合桩桩顶三向调节装置精确定位安装;组合梁的钢梁在工厂加工成板单元后,船运至中山预制场进行整孔组拼,混凝土桥面板采取纵向分块、横向整幅预制,二者结合成组合梁后由“天一号”运架一体船逐片吊装。%The non‐navigational channel bridge in the shallow water area of Hongkong‐Zhuhai‐Macao Bridge is a continuous composite girder bridge with separated left and right decks .The bridge has 11 continuous units of spans of 85 m .T he foundation of the piers is formed of concrete‐filled steel tubular piles ,the pile caps and pile shafts were prefabricated and assembled in the workshop ,and the pile caps were deeply buried in the seabed .The superstructure adopts compos‐ite girder structure .Complicated geological condition and harsh environment render the bridge site quite challenging for construction .The Crane Little Swan ,a catamaran used to lift and erect gird‐ers ,was employed to carry the overall guiding frame system ,to realize three times of positioning of the composite foundation steel tubes and precisely control the driving of the steel tubes .The pile cap and the bottom lift of the pier are monolithically prefabricated ,during the manufacture of which ,the reinforcement was divided

  15. Introduction (United States)

    Narlikar, J. V.; Sathyaprakash, B. S.


    colleague Kumar (S.M.) Chitre and the younger one, Ajit Kembhavi, and the organizational infrastructure of TIFR. In particular, the then administrator dealing with scientific meetings, Parelkar enthusiastically joined me to set up the local boundary conditions in Goa. To get our priorities right, we first picked upon Hotel Mandovi in Panjim (Capital of Goa) as the nodal hotel for catering, accommodation, and arrangements of the academic sessions. We were expecting around 100 participants with 50% from abroad. Kamat, the Manager of Hotel Mandovi, promised all help including beds in nearby hotels to make up any shortfall. Regarding the quality of food, for which Hotel Mandovi was justly famous, its in-charge, Satish Prabhu took care of all our worries. Delegates may still recall the various Goan delicacies featured on the conference menus. Parelkar negotiated the basic deal with the hotels to extract the maximum benefits for the conference. But we were still rather vulnerable in lack of the local conditions. An unexpected helping hand came to make up for our lack of local knowledge. The amateur astronomer organization, called ''Friends of Astronomy in Goa'', led by their venerable President, Percival Noronha offered to run errands for us and play the role of local volunteer. Noronha had been associated with the state government of Goa, since the days when it was a Portuguese colony. His 'inside knowledge' came in useful, especially when he advised us to request the Chief Minister, Pratapsingh Rane to entertain the conference participants in the state catamaran. Somewhat hesitatingly, I wrote a request letter, and to my delightful surprise, the CM agreed. Indeed, the boat-ride followed by the CM's riverside banquet was the entertainment high point of the conference. The food, Goan drinks, and musical entertainment were well appreciated by the participants, and an uninitiated person might be forgiven for thinking that ICGC stood for ''International Conference on Goan