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

    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

    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.


    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.

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

    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.

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



    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.

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

    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.

  8. 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

    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.

  9. New concept of solar-powered catamaran fishing vessel

    Utama, IKAP; Santosa, PI; Chao, R.M.; Nasiruddin, A.


    It has been considered that the availability of fossil fuels is getting rare and hence becoming more expensive. Its exploration has moved from onshore to offshore together with advanced technology involved thus causing higher cost to the fuels to be ready to use. This fact has caused (in particulars) the fishermen cannot afford to buy the fuel so that they are vulnerable to live in poverty. Recent survey shows that more than 50% of fishing boats, owned by traditional and low econo...

  10. 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...

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

    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.

  12. Radiated Sound of a High-Speed Water-Jet-Propelled Transportation Vessel.

    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

  13. Cost Earnings Data 2001 - American Samoa Longline

    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...

  14. 77 FR 10802 - Requested Administrative Waiver of the Coastwise Trade Laws: Vessel SILVER MOON; Invitation for...


    ... 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...


    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...

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

    Fengmei Jing


    Full Text Available 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 platform of tidal current power station are studied. And they are compared with its economic, efficiency of turbine and stability of station. It is found that the catamaran is optimal choice. Based on basic ship theory and using software MOSES, the stability of Catamaran tidal current power station is also calculated. The research of this study is significant and it will be as the reference for the future study.

  17. Seacoaster advanced marine vehicle. Final report

    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.

  18. AMD183穿浪双体客船

    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.

  19. Experimental Study on Hysucat Vessels

    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.

  20. 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...

  1. Sustainable Oceanographic Vessels - Setting an Example

    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.


    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...


    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.

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

    Ruiyin Song; Meiqin Zhang; Xiaohua Qian; Xiancheng Wang; Yong Ming Dai; Junhua Chen


    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...

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

    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

  6. Yachting club

    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...

  7. Yachting Club

    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...


    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.

  9. High Performance Marine Vessels

    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...

  10. 世界高速车客渡船的三大格局



    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.


    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.

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

    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.

  13. LKB-Based Evaporation Duct Model Comparison with Buoy Data.

    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.

  14. CERN Yachting club

    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.   ...

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

    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.




    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...

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

    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.

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

    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. 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



    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


    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&...

  1. Yachting Club

    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...

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

    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.

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

    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.

  4. 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

    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.

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

    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.




    Full Text Available Finance plays a crucial role in accelerating any business activity/economic development and fisheries sector is not an exception. The economic activities of the fishing villages mainly depend upon the availability of credit at reasonable cost to enhance production and income. Lack of institutional credit is an obstacle to further development of the small-scale fisheries sector. In this context the researcher has attempted to study the credit needs of the fishermen, various sources of institutional credit availed by them and their experience with financial institutions. This is an empirical study completed through field study. Thoothukudi District has been selected as the study area. In the study area only 152 respondents have accessed the various institutional agencies and availed 250 loans for meeting the expenditures. The data were collected using a survey schedule. Mean, standard deviation, co-efficient of variation and the One-way ANOVA were used. It is inferred that most of loans are availed from the Cooperative banks (42% followed by Commercial banks (21%. The vallam craft owners have borrowed the highest number of loans followed by catamaran and FRPboat owners. From the analysis it could be understood that majority of the loans availed from the financial institutions are less than Rs.25, 000 and the financial institutions fail to come forward to provide higher loan amount for the craft owners. Consequently for want of further loans they fall in the clutches of middlemen. Thus it is clear that the financial institutions play a very little role in bringing up the economic status of the fishermen in Thoothukudi District.

  7. Kootenai River Experiment: An overview of river flow observations and modeling (Invited)

    Reniers, A. J.; Macmahan, J. H.; Swick, W.; Ashley, W.; Brown, J.; Tuggle, C.; Rynne, P.; Thornton, E. B.; Holland, K.


    Novel river flow observations were obtained during a recent field experiment at the Kootenai River, Idaho, in August 2010. The focus of the experiment was on the 3D velocity structure of the flow, secondary circulations, and concurrent large scale turbulence as function of variation in bed level and river alignment. A combination of in-situ observations and three-dimensional (3D) modeling is used to explore the dynamics of river flow in two distinctly different reaches of the same river. The braided reach exhibits fast flows (typically larger than 0.5 m/s) in relatively shallow water (~3 m), whereas the meandering reach has smaller flows (less than 0.5 m/s) and is significantly deeper (approximately 8 m). In the braided reach, a suite of instruments was deployed to examine the flow dynamics including a mobile frame equipped with an ADV, horizontal-facing custom ADCP, and a coherent lagged array of EM current meters to examine temporal and spatial turbulence characteristics. ADCPs mounted on small stationary catamarans were deployed to measure the mean vertical structure of the river flow at a large number of locations (>100). Unmanned vehicles were used in the meandering reach to examine the vertical structure of the mean river flow and in both reaches GPS-equipped drifters were used to map the Lagrangian river flow dynamics. GPS-equipped drifters were also used in combination with dye experiments to describe river mixing. Preliminary DELFT3D model simulations are used to identify gaps in our modeling approach/concepts by examining model-observation mismatches. An overview of the field observations and model simulations will be presented at the conference.

  8. 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

    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.

  9. Shallow water MT technology

    Complete text of publication follows. The company 'Nord West Ltd' developed in 2008 an instrumentation and technology named AQUAMATIC (AQUA MAgnetoTellurIC) aimed at carrying out MT studies in shallow water basins (transition zone). It consists of floating containers for industrial ground-based MT instrument produced by the company 'Phoenix Geophysics', special sea electrodes and cables. The instrumentation suggests that measurement of the electric field at the seafloor, while the magnetic field is measured on-land. AQUAMATIC is a unique acquisition system designed for shallow water with depths of a few meters; moreover it can be applied in the conditions of strong currents and wind waves. The application of AQUAMATIC makes it possible to carry out MT surveys in transition zones with the depths less then 20 m, which are white spots of geophysical studies, where nor traditional sea technology, not traditional on-land technology could be applied. The main advantage of the elaborated technology is a relatively low cost of survey. Due to the system's small size and weight it is not necessary to use a specially equipped vessel to exploit the system, as it is required of deep sea seafloor MT soundings, just a small catamaran and a boat are quite enough. The system's small weight makes it possible for 2-3 people to install the instrument. It is also more economic in terms of time spent for one sounding: at favorable weather conditions one team may operate up to 5 stations. The first practical application of AQUAMATIC system were experimental MT studies along two profile in the Volga River estuary and the northeastern part of the Caspian Sea with typical depth of 1-2 meters. The results obtained at the Caspian Sea open new prospects for MT method; which can be now used at earlier inaccessible vast transition zones at estuaries, shallow continental shelf, big rivers and lakes.


    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. 


    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 °.

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

    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.

  13. The history and source of particulate 137Cs and 239,240Pu deposition in sediments of the Ob River Delta, Siberia

    This paper presents the first results of a project designed to examine the transfer of particle-associated artificial radionuclides down the Ob River in Siberia to its delta over the past 5 decades. The main sources include fallout from atmospheric nuclear weapons tests and weapons complexes and test sites of the Former Soviet Union in or near the Ob watershed. The approach is to measure the accumulation of the radionuclides in undisturbed delta sediments - obtaining a record of their deposition over time. These records were found in sediments of shallow lakes apart from, and connected to, the main channel. Sediment cores were collected in the summer of 1994 using a shallow draft catamaran to reach these lakes from a support ship in the main channel. Measurements are presented on the depth distributions of 137Cs and Pu isotopes and their inventories in a series of dated sediment cores - including one from a location in the Taz Estuary (which does not receive Ob River sediments). Sediment dating was carried out using the excess 210Pb technique. The results obtained are compared with known information on the temporal history of releases from the various sources and characteristics of the isotopic composition of the sources. The results show that good records of radionuclide deposition indicate that the major fraction of 137Cs and Pu isotopes deposited in these delta sediments comes from atmospheric nuclear weapons test fallout - both delivered directly from the atmosphere and from downstream transport of watershed sediments. No more than 25% of the observed inventories could be derived from other sources

  14. Development and Characteristics of a Mobile, Semi-Autonomous Floating Platform for in situ Lake Measurements

    Barry, D.; Lemmin, U.; Le Dantec, N.; Zulliger, L.; Rusterholz, M.; Bolay, M.; Rossier, J.; Kangur, K.


    In the development of sustainable management strategies of lakes more insight into their physical, chemical and ecological dynamics is needed. Field data obtained from various types of sensors with adequate spatial and temporal sampling rate are essential to understand better the processes that govern fluxes and pathways of water masses and transported compounds, whether for model validation or for monitoring purposes. One advantage of unmanned platforms is that they limit the disturbances typically affecting the quality of data collected on small vessels, including perturbations caused by movements of onboard crew. We have developed a mobile, semi-autonomous floating platform with 8 h power autonomy using a 5 m long by 2.5 m wide catamaran. Our approach focused on modularity and high payload capacity in order to accommodate a large number of sensors both in terms of electronic (power and data) and mechanical constraints of integration. Software architecture and onboard electronics use National Instruments technology to simplify and standardize integration of sensors, actuators and communication. Piecewise-movable deck sections allow optimizing platform stability depending on the payload. The entire system is controlled by a remote computer located on an accompanying vessel and connected via a wireless link with a range of over 1 km. Real-time transmission of GPS-stamped measurements allows immediate modifications in the survey plan if needed. The displacement of the platform is semi-autonomous, with the options of either autopilot mode following a pre-planned course specified by waypoints or remote manual control from the accompanying vessel. Maintenance of permanent control over the platform displacement is required for safety reasons with respect to other users of the lake. Currently, the sensor payload comprises an array of fast temperature probes, a bottom-tracking ADCP and atmospheric sensors including a radiometer. A towed CTD with additional water quality

  15. CHIRP survey of the submerged harbors of King Herod's Caesarea, offshore Israel - looking for evidence of ancient disasters

    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").

  16. Monitoring Sea Level At L'Estartit, Spain

    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

  17. Experiences on Altimeter Calibration at Ibiza Island and Cape of Begur (Spain)

    Martinez Benjamin, J. J.; Martinez Harcia, M.; Ortiz Castello, M. A.; Talaya, J.; Baron, A.; Rodriguez Velasco, G.; Martín Davila, J.; Garate, J.; Bonnefond, P.; Garcia, C.


    Three preliminary camp aigns for TOPEX /POSEIDON (T/P) wer e made in March 1999 and July 2000 and for JASON-1 in August 2002, in the NW Mediterran ean Sea at th e Begur Cape area. Dir ect abso lute altimeter calibration , and mapping of the sea surface, w ere made in these camp aigns from dir ect overflights using GPS buoys with a toroidal design performed at the I CC based in the orig inal design of the Univ ersity of Colorado at Boulder and a estimation of the TOPEX A lt- B bias w as made. A Spanish JASON-1 geoid gradien t campaign with Fench support has been made in June 2003 at the Ibiza island in the NW Mediterr anean Sea. Th e main objectiv e has b een to map w ith a new d esign ed, builded and calibrated GPS catamar an, the lo cal geoid gradien t in three ar eas around Ibiza island under the ascending (187) and descending (248) Jason-1ground tracks. The catamaran equ ipped with two GPS antennas to perform continuous sea lev el measur ements was towed by the Patro l Dev a from th e Span ish N avy. Five GPS reference stations were dep loyed on Ibiza island: one in Portinatx, two in San Anton io and two in Ibiza. The marin e geo id has been used to relate the coastal tide gauge data from Ibiza and San An tonio h arbours to off- shore altimetric data. In th e framework of the campaign, the levelling of the Ibiza and San Anton io tide gauges to the r espective GPS mark ers w as p erformed. We present synth esis of the resu lts obtained from Topex/Poseidon and th e first r esults on Jason-1 altimeter calibration using the direct measurements from GPS buoys and the derived marin e geoid. Th e Ibiza results agree relativ ely w ell with resu lts ob tained at Corsica, Harvest and Bass Strait calibration permanen t sites. Moreov er, the geod etic activities (e.g., GPS, levelling) has p ermitted to build a very accurate (few mm) local n etwork link ed to th e European one, w ith a reference frame compatible with th e satellite altimetry missions (ITRF2000). The GPS

  18. Sediment Coring of the Proglacial Lake Donguz-Orun (northern Caucasus, Russia)

    Alexandrin, Mikhail; Solomina, Olga; Kalugin, Ivan; Darin, Andrey; Nesje, Atle


    So far, no high-resolution reconstructions of climate and glacier variations based on lake sediment properties are available in Caucasus Mountains. In other presently glaciated regions this approach is proved to be very useful for this purpose (e.g. Nesje et al., 2001, 2011; Bakke, 2005, Nesje, 2009) In this paper we report the first results of the sediment coring of Donguz-Orun Lake (N 43°13'26", E 42°29'35") situated in the upper reaches of Donguz-Orun-Kyol, a tributary of Baksan river in the Elbrus region of Northern Caucasus, a typical proglacial lake dammed by a lateral moraine deposited by the Donguz-Orun Glacier. It is a drainage lake with several inflowing glacial streams and effluent river Donguz-Orun. The surface area is around 105 000 m2 with a water volume of 465 000m3. The average water depth is around 4.5 m, with a maximum water depth of 14 m. The deepest part is found close to the moraine dam in the narrow northern part of the lake. This is normally consistent with this type of glacial lake systems. An intensive gravitational drift of the moraine material towards the lake is observed. These non-rounded moraine boulders constitute a significant part of the lakebed. Lacustrine sediments are present though. The coring campaign from Institute of Geography, Russian Academy of Sciences (August 2012) used a modified piston corer with a 110 mm-diameter plastic tube (Nesje, 1992) mounted on the inflatable catamaran to obtain lake sediments from Lake Donguz-Orun. A 28-cm long core was retrieved from a water depth of around 7 m. The sediments consist of regularly laminated, fine beige clay, with several interlayers of sand. The coring process appeared to be challenging due to the stiffness of clay, which led to extreme bending of the sediment layers in the basal part of the core. The original thickness of the sediments was obviously higher than observed in the core. In order to clarify the recent history of the Donguz-Orun glacier, we used lichenometry and

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

    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

  20. Immersive, hands-on, team-based geophysical education at the University of Texas Marine Geology and Geophysics Field Course

    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

  1. System identification and the modeling of sailing yachts

    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.)

  2. Introduction

    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