Sample records for drydocks

  1. 46 CFR 31.10-21 - Drydock examination, internal structural examination, cargo tank internal examination, and... (United States)


    ..., and other void spaces on tank barges must be opened and checked from on-deck for the presence of water... follows: (1) Except under paragraph (a)(2) of this section, vessels that operate in salt water must be... that operate in fresh water at least six months in every 12 month period since the last drydock...

  2. EX1006 Hawaii to San Francisco Transit to Drydock (EX1006, EM302) on Okeanos Explorer in Hawaii, US West Coast (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Okeanos Explorer (EX) will transit from Honolulu, HI to San Francisco for the winter inport and drydock period. During the transit, the EX will perform 24-hour...

  3. Were Viking Dry-dock methods in the Americas used earlier to Build Pyramids, with Outflow Eroding the Sphinx, and were Stonehenge, the Obelisks, and Moas Similarly Erected? (United States)

    McLeod, Edward; McLeod, Roger


    Chisel-quarried recycled granite in MA is datable by runes to 1069 CE; it could corroborate dating by a LIDAR. Associated sites, possibly used by Vikings to dry-dock their ships, could have exploited lock-like controls, possibly a continued technology. Site-leveling at the Giza Pyramids proves water was used. `Locks' and body-immersion worked for building, moving, erecting, or watering, at sites like Stonehenge, The Hanging Gardens at Babylon, the Moas of Easter Island, or The Pyramids, where the eroding water discharge was deliberately flushed over the Sphinx complex. It enhance the electromagnetically excited blue light signals we can detect, especially at sites frequented by Molocket of ME. Information, as at America's Stonehenge, in NH, and constructions at Acton MA, at Giza or at Rumford ME proves that the Pyramids and Sphinx were engineered and built about 4500 BP.

  4. Earthquake Resistant Submarine Drydock Block System Design (United States)


    acceleration time history. It Is observed that the block on block surfaces for this system had been painted. According to Rabinowicz (1987) [13J, a...Maryland, 1982, p. 272. 166 13. Rabinowicz , Ernest, Lecture, "Tribology", M.I.T., Course 2.800, Fall 1987. 14. Telephone conversation between Tingley

  5. Drydock Extension - A 1980 Underwater Technology Survey for Extension of Time between Drydocking (United States)


    Illuminated Ambient Viewing Environments," Oceanautics, Inc., May 1979. 192. Wadsworth, J. F., "Underwater £nspection of Fleet Moorings," Civil...ed Economia /Cleaning the Underwater Hulj with the Afloat.: Tenhnicajl snd Ernnonnin’ Cnnsidpra tnn_ 3. Publication Date. 4. Key Words/Descriptors

  6. Non-Linear Material Three Degree of Freedom Analysis of Submarine Drydock Blocking System (United States)


    TEST FOR KEEL ELOCK LIFTOFF 1 612 1 613 if (flag6.eq. ) then 1 614 go to 450 1 615 else if (rf3. it.O ) then 1 616 time6=dtau*(1-l) 1 617 f1.ag6:1 1 618... flt3 -)3,:) i .-ico: Obs -8500$ 1 .S 0 Q0: * 0 .9ZX - .mE - r -?9m0e.m m5!1 4C tr,4 c .󈧙𔃾%E -!. jC 6 05 X S43: ;- ’ 0:ZJ,, c A: EtX’ BL : = 2 EB

  7. Library holdings for EX1006: Hawaii to San Francisco Transit to Drydock on NOAA Ship Okeanos Explorer between October 10, 2010 and October 18, 2010 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Library Catalog may include: Data Management Plans, Cruise Plans, Cruise Summary Reports, Scientific "Quick Look Reports", Video Annotation Logs, Image Collections,...

  8. 75 FR 27551 - Duke Energy Carolinas, LLC; Notice of Availability of Environmental Assessment (United States)


    ... ramp would serve a private, dry-dock boat-storage facility intended for the residents of Wilderness.... The proposed marina would consist of 2 floating, cluster docks accommodating a total of 30 watercraft...

  9. 46 CFR 185.202 - Notice of casualty. (United States)


    ... does not include the cost of salvage, cleaning, gas freeing, drydocking, or demurrage. (b) A vessel is... reporting requirements of the Occupational Safety and Health Administration (OSHA) in 29 Code of Federal Regulations (CFR) part 1904. (c) Notice given as required by § 185.203 satisfies the requirement of...

  10. 32 CFR 700.857 - Safe navigation and regulations governing operation of ships and aircraft. (United States)


    ... naval shipyard or station, in drydock, or in the Panama Canal. During an armed conflict, an exercise... standards and regulations governing shiphandling, safe navigation, safe anchoring and related operational matters shall be promulgated by the Chief of Naval Operations. (c) Professional standards and...

  11. Marine Seismic System Deployment (MSS). Phase 2. Investigation of Techniques and Deployment Scenarios for Installation of Triaxial Seismometer in a Borehole in the Deep Ocean (United States)


    Puerto Rico Drydock and Marine Terminals, Inc. is situated on the south side of Isla Grande (See Appendix C), in close proximity to downtown San...Florentin, Vice-President, Operations Antonia Maria Manrrique, #4 La Cornisa, Las Palmas Gran Canaria, Spain Telephone: 27-3650 9- 9- [ APPENDIX A TRAILER

  12. 46 CFR 169.234 - Integral fuel oil tank examinations. (United States)


    ... 46 Shipping 7 2010-10-01 2010-10-01 false Integral fuel oil tank examinations. 169.234 Section 169... VESSELS Inspection and Certification Drydocking Or Hauling Out § 169.234 Integral fuel oil tank examinations. (a) Each fuel oil tank with at least one side integral to the vessel's hull and located within...

  13. Feasibility of Underwater Friction Stir Welding of Hardenable Alloy Steel (United States)


    case, for drydocking. A single tool made of polycrystaline cubic boron nitride (PCBN) with a Tungsten -Rhenium binder was used to conduct a series of...polycrystalline cubic boron nitride (PCBN) with a Tungsten -Rhenium binder was used to conduct a series of bead-on-plate FSW traverses, approximately 64...joining of aluminum structural components in the Littoral Combat Ship (LCS) and processing of the nickel aluminum bronze used in U.S. Navy propellers. In

  14. Clear Purpose, Comprehensive Execution: Raymond Ames Spruance (1886-1969) (United States)


    Shipbuilding and Drydock, the New York Navy Yard, and the Bureau of Engineering.11 In fact, Spruance found him- self in danger of becoming a de facto...told Kalbfus that his pet doctrinal publication, Sound Military Decision, was an elaborate cookbook of form over substance, in which an orderly process...his rapid wartime advancement. His views were esteemed by his juniors, his peers, and his seniors. With his staff he talked endlessly, often while

  15. Feasibility of underwater friction stir welding of HY-80 steel


    Stewart, William Chad


    Approved for public release; distribution is unlimited. The purpose of this thesis is to determine the feasibility of underwater friction stir welding (FSW) of high-strength; quench and temper low carbon steels that are susceptible to hydrogen-assisted cracking (HAC). The specific benefits of underwater FSW would be weld repairs of ship and submarine control surfaces and hulls without the need for drydocking and extensive environmental control procedures. A single tool of polycrystallin...

  16. Best Practices: High Levels of Knowledge at Key Points Differentiate Commercial Shipbuilding from Navy Shipbuilding (United States)


    Figures Figure 1: Typical Shipbuilding Process 3 Figure 2: Cruise Ship Block Fabrication 5 Figure 3: Cruise Ship Block Outfitting 6 Figure 4: Cruise ... Ship Grand Block 7 Figure 5: Cruise Ship Blocks in Drydock after Keel Laying 8 Figure 6: Major Navy Shipbuilders and Associated Product Lines 11...Emma Maersk 20 Figure 10: Block Definition Plan for a Cruise Ship 26 Figure 11: Navy Practices: Significant Risks Remain Unresolved at Contract

  17. A new multibeam swath mapping echosounder for USCGC Healy (United States)

    Chayes, D. N.; Roberts, S. D.; Perron, P. J.; Beaudoin, J.; Arko, R. A.; Perry, R. S.


    The Healy is the primary U.S. research icebreaker working in the Arctic. In 2003, the UNOLS Arctic Icebreaker Coordinating Committee (AICC) endorsed a plan to replace the aging SeaBeam 2112 multibeam echosounder that was purchased for the Healy at the beginning of construction and delivered with the vessel. Replacement was judged necessary due primarily to age and support issues associated with the original multibeam. Although the original plan was to do the replacement during the regularly scheduled drydock during CY 2006-07, the goal was realized during the CY 2009-10 drydock in Seattle, WA. The selected replacement was a Kongsberg EM122 with one degree (1°) transmit and two degree (2°) beam widths. The transducers are recessed behind windows to protect them from ice damage. The EM122 is configured with water column and raw stave data recording capabilities along with a synchronization interface. Due to the long cable runs and the potential for electromagnetic interference (EMI), a fiberoptic interface was implemented for this system. The installation was completed just prior to departure from the drydock in mid-March 2010, with integration into the existing data system largely completed prior to getting underway for engine trials. A successful Sea Acceptance Test was completed on June 12, 2010, just prior to the first of three research cruises in the Arctic during the 2010 season. Details of the installation and performance of the system will be presented.

  18. 佐敦SeaQauntum系列无锡防污漆

    Institute of Scientific and Technical Information of China (English)



    About thirty years after the invention of TBT SPC, Jotun develops a new generation of Tin-free Self Polishing Antifouling Paint based on the mechanism of hydrolysis-SeaQuantum. Hydrolysis assures SeaQuantum of equal, if not better performance than the best TBT containing selfpolishing antifouling. New polymer and active ingredients make it possible for SeaQuantum to meet the IMO draft and to provide antifouling protection up to 60 months. The performance of SeaQauntum has been well proven by the test of more than 400 drydockings and 120 new buildings in last nine years.

  19. Observation on fouling organisms collected from Indian naval ships at Bombay

    Directory of Open Access Journals (Sweden)

    V. Gopalakrishnan


    Full Text Available Fouling organisms collected from Indian Naval Ships dry-docked at Bombay during a period of two years (July 1956-June 1958 were studied in detail. Forty six of the forms collected have been identified. The most important groups of ship-fouling Organisms in Bombay waters are Barnacles, Hydroids, Polyzoans and Tube-worms. Eleven different Fouling Communities have been found to dominate the settlements on the hulls at different occasions. Definite zonations that could be observed were restriction of green algae to the boot-top area and mussels and oysters to the pipes and gratings. An attempt has been made to find the sequence of settlement of the different major fouling groups. Some general remarks on the observations have also been included.

  20. Diversitas Kultural dan Pengelolaan Konflik Dalam Sebuah Organisasi Bisnis Multinasional

    Directory of Open Access Journals (Sweden)

    MC Ninik Sri Rejeki


    Full Text Available The theoritical analysis is inspired by the labor riot occurred in Drydocks World Graha Shipyards Company in Batam April 22, 2010. This case has reminded us to consider the importance of diversity management for business organization. Such organization has a reality of cultural diversity in its employees and usually it is a multinational company. Such company has grown and expanded in accordance with the development of the global economic order. The reality of cultural diversity actually can be positive forces to sustain the dynamics of the organization, but if not properly managed it can make the negative impact of disadvantageous communication climate. It can enrich the communication climate practices of racism and discrimination. The goal of diversity management is to maximize the positive forces of cultural diversity and to minimize its negative impacts. Management of diversity is itself a way of managing an organization that requires the multicultural paradigm. Inter-group conflict management is an integral part of the management of diversity. At the group level, it is necessary to understand the factors of inter-group conflict. When the conflict as the adverse effect of cultural diversity occurs, that is needed is a constructive management. Parties who have a burden of adaptation should be accommodative to other parties. Accommodation is conducted in the way of viewing the conflict, attitudes, and management style. It is also needs to be developed a communication climate that may reduce the prejudices which is the source of the practices of racism and discrimination.

  1. Lamb wave detection of limpet mines on ship hulls. (United States)

    Bingham, Jill; Hinders, Mark; Friedman, Adam


    This paper describes the use of ultrasonic guided waves for identifying the mass loading due to underwater limpet mines on ship hulls. The Dynamic Wavelet Fingerprint Technique (DFWT) is used to render the guided wave mode information in two-dimensional binary images because the waveform features of interest are too subtle to identify in time domain. The use of wavelets allows both time and scale features from the original signals to be retained, and image processing can be used to automatically extract features that correspond to the arrival times of the guided wave modes. For further understanding of how the guided wave modes propagate through the real structures, a parallel processing, 3D elastic wave simulation is developed using the finite integration technique (EFIT). This full field, technique models situations that are too complex for analytical solutions, such as built up 3D structures. The simulations have produced informative visualizations of the guided wave modes in the structures as well as mimicking directly the output from sensors placed in the simulation space for direct comparison to experiments. Results from both drydock and in-water experiments with dummy mines are also shown.

  2. Three decades of TBT contamination in sediments around a large scale shipyard. (United States)

    Kim, Nam Sook; Shim, Won Joon; Yim, Un Hyuk; Ha, Sung Yong; An, Joon Geon; Shin, Kyung Hoon


    Tributyltin (TBT) contamination in sediments was investigated in the vicinity of a large-scale shipyard in the years after the implementation of a total ban on the use of TBT based antifouling paints in Korea. Extremely high level of TBT (36,292ng Sn/g) in surface sediment was found at a station in front of a drydock and near surface runoff outfall of the shipyard. TBT concentration in surface sediments of Gohyeon Bay, where the shipyard is located, showed an apparent decreased TBT concentration gradient from the shipyard towards the outer bay. The vertical distribution of TBT contamination derived from a sediment core analysis demonstrated a significant positive correlation (r(2)=0.88; pTBT concentrations at six stations surveyed before (2003) and seven years after (2010) the total ban showed no significant differences (p>0.05). Despite the ban on the use of TBT, including ocean going vessels, surface sediments are still being heavily contaminated with TBT, and its levels well exceeded the sediment quality guideline or screening values.

  3. Antioxidant responses versus DNA damage and lipid peroxidation in golden grey mullet liver: a field study at Ria de Aveiro (Portugal). (United States)

    Oliveira, M; Ahmad, I; Maria, V L; Pacheco, M; Santos, M A


    The present work aimed to investigate golden grey mullet (Liza aurata) liver protection versus damage responses at a polluted coastal lagoon, Ria de Aveiro (Portugal), as a tool to evaluate the human impacts on environmental health at five critical sites in Ria de Aveiro (Portugal) in comparison to a reference site (Torreira; TOR). Protection was evaluated by measuring non-enzymatic [total glutathione (GSHt) and non-protein thiols (NPT)] and enzymatic [catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GR)] antioxidant defenses. Damage was assessed as DNA integrity loss and lipid peroxidation (LPO). No significant differences were found between sites in terms of non-enzymatic defenses (GSHt and NPT). CAT did not display significant differences among sites. However, GPx at Barra (BAR, associated with naval traffic), Gafanha (GAF, harbor and dry-dock activities area), Laranjo (LAR, metal contaminated associated with chlor-alkali plant), and Vagos (VAG, contaminated by polycyclic aromatic hydrocarbons) was significantly lower than the reference site. GST was lower at GAF, Rio Novo do Príncipe (RIO, pulp mill effluent area), LAR, and VAG, whereas GR was lower at RIO. The loss of antioxidant defenses was paralleled by higher LPO levels only at GAF and VAG. However, no DNA integrity loss was found. Results highlight the importance of the adopted multibiomarkers as applied in the liver of L. aurata in coastal water pollution monitoring. The integration of liver antioxidant defense and damage responses can improve the aquatic contamination assessment.

  4. Mechanical Response of Geotextile Bag with Sand Cofferdam under Pumping Disturbance of Zhoutouzui Immersed Tunnel%洲头咀沉管隧道干坞抽水扰动下模袋砂围堰力学响应研究

    Institute of Scientific and Technical Information of China (English)

    杨春山; 魏立新; 莫海鸿; 陈俊生; 刘力英


    The detailed model for dry-dock pumping process was established based on Zhoutouzui immersed tun-nel in Guangzhou to investigate mechanical response of geotextile bag with sand cofferdam. The performance of wa-terstop wall combined of steel sheet pile and bagged clay was evaluated and the deformation of geotextile bag with sand cofferdam was explored as well as the tension of geotextile bag was calculated, which simplified calculation method was proposed. The results show that the effect of combined waterstop wall is excellent. The influence of dry-dock pumping on cofferdam deformation is significant, which is a homodromous linear relation. The density of cof-ferdam increase caused by dewatering, which increases overlying pressure from upper geotextile bag to lower one and makes geotextile vertical flattening deformation. And then flattening deformation and seepage caused by head difference make cofferdam horizontal displacement. The tension of geotextile bag increases with water level decrease in a nearly linear relation and comparing with numerical calculation results indicate that simplified calculation meth-od of tension is reasonable.%为深入研究模袋砂围堰对沉管隧道干坞抽水力学响应规律,以广州洲头咀沉管隧道模袋砂围堰工程为背景,建立干坞抽水全过程精细数值模型。计算验证了钢板桩+袋装黏土组合芯墙止水性能。分析了干坞抽水引起的模袋砂围堰变形规律。并揭示了围堰土工模袋张力分布规律,此外提出模袋张力简化计算方法。研究表明:模袋砂围堰钢板桩+袋装黏土组合防渗芯墙止水效果良好,能有效控制临江侧水流渗入干坞侧;干坞侧抽水对模袋砂围堰变形产生了显著的影响,变形与坞内下降水位近似呈同向线性关系;坞内水位降低使围堰重度由浮重度变为干重度,引起模袋砂压实而出现较大竖向位移;围堰竖向压缩和水头差引起的渗流作用又

  5. Tres grandes plataformas marinas Mar del Norte

    Directory of Open Access Journals (Sweden)

    Soulas, R.


    Full Text Available This article analyzes the different building stages of three large sea platforms. After studying the structure's main characteristics, preparing scale models and calculating ail the elements, platform construction was carried out in three stages: — Dry-dock construction of the hull base. — Installation in the water and finishing the structure. — Immersion and bridge installation. Finally, the necessary operations to move the platform to its definite location were carried out. The structures are formed by a parallelepiped hull of reinforced concrete, divided into compartments by means of vertical orthogonals panels on top of which 2 or 4 piles are placed to support the bridge.

    En este artículo se analizan las diversas etapas en la realización de tres grandes plataformas marinas. Después de un estudio de las características principales de la estructura, ensayos en modelo reducido y cálculo de todos los elementos, se procede a la construcción de las plataformas en tres fases: — Construcción en seco de la base del casco. — Colocación en el agua y acabado de la estructura. — Inmersión y colocación del puente. Por último, se realizan las operaciones necesarias para llevar la plataforma a su ubicación definitiva. Las estructuras están formadas por un casco paralelepipédico de hormigón armado, dividido en compartimientos mediante tabiques verticales ortogonales y sobre el que se han colocado 2 ó 4 pilas que soportan el puente.

  6. Numerical simulation of groundwater flow at Puget Sound Naval Shipyard, Naval Base Kitsap, Bremerton, Washington (United States)

    Jones, Joseph L.; Johnson, Kenneth H.; Frans, Lonna M.


    Information about groundwater-flow paths and locations where groundwater discharges at and near Puget Sound Naval Shipyard is necessary for understanding the potential migration of subsurface contaminants by groundwater at the shipyard. The design of some remediation alternatives would be aided by knowledge of whether groundwater flowing at specific locations beneath the shipyard will eventually discharge directly to Sinclair Inlet of Puget Sound, or if it will discharge to the drainage system of one of the six dry docks located in the shipyard. A 1997 numerical (finite difference) groundwater-flow model of the shipyard and surrounding area was constructed to help evaluate the potential for groundwater discharge to Puget Sound. That steady-state, multilayer numerical model with homogeneous hydraulic characteristics indicated that groundwater flowing beneath nearly all of the shipyard discharges to the dry-dock drainage systems, and only shallow groundwater flowing beneath the western end of the shipyard discharges directly to Sinclair Inlet.Updated information from a 2016 regional groundwater-flow model constructed for the greater Kitsap Peninsula was used to update the 1997 groundwater model of the Puget Sound Naval Shipyard. That information included a new interpretation of the hydrogeologic units underlying the area, as well as improved recharge estimates. Other updates to the 1997 model included finer discretization of the finite-difference model grid into more layers, rows, and columns, all with reduced dimensions. This updated Puget Sound Naval Shipyard model was calibrated to 2001–2005 measured water levels, and hydraulic characteristics of the model layers representing different hydrogeologic units were estimated with the aid of state-of-the-art parameter optimization techniques.The flow directions and discharge locations predicted by this updated model generally match the 1997 model despite refinements and other changes. In the updated model, most

  7. Ship operation and failure mode analysis using a maneuver simulator (United States)

    Cabrerizo-Morales, Miguel Angel; Molina, Rafael; de los Santos, Francisco; Camarero, Alberto


    In a ship or floating structure operation the agents that contribute to the systems behaviour are not only those derived from fluid-structure interaction, but also the ones linked to mooring-control line set-up evolution and human interaction. Therefore, the analysis of such systems is affected by boundary conditions that change during a complete operation. Frequently, monitoring techniques in laboratory (model) and field (prototype) are based in different instrumental techniques adding difficulty to data comparison and, in some cases, inducing precision and repeatability errors. For this reason, the main aim of this study is to develop the methods and tools to achieve a deep knowledge of those floating systems and obtain capabilities to optimize their operationally thresholds. This abstract presents a methodology and an instrumental system applicable both in field and laboratory: SRECMOCOS Project (Small scale REal-time Caisson MOnitoring and COntrol System). SRECMOCOS compiles three modules. For the monitoring and control of the structure it has been developed a synchronized open and modular microcontroller-based electronic system that comprises sensors, to monitor agents and reactions, and actuators to perform pertinent actions after processing the sensors' data. A secondary objective has been to design and implement a global scaled simulator (1:22), at the 3D basin of The Harbour Research Lab at Technical University of Madrid, in which climatic agents and those derived from the rig/maneuvering setup and the structural design were included. The particular case of Campamento's drydock, in Algeciras Bay (Spain), has been used to apply and validate the methodology. SRECMOCOS Project conjugates control, monitoring and wireless communication systems in a real time basis, offering the possibility to register and simulate all the parameters involved in port operations. This approach offers a step forward into a monitoring strategy to be included in monitoring

  8. Measurement of Large-Scale Sediment Transport Dynamics Using Multibeam Sonar (United States)

    Simmons, S. M.; Parsons, D. R.; Best, J. L.; Malzone, C.; Keevil, G.


    Multibeam Echo-Sounder (MBES) sonar systems have developed rapidly over recent decades and are now routinely deployed to provide high-resolution object detection and bathymetric surveying in a range of aquatic environments, from the deep-sea to lakes and rivers. MBES systems were developed for bottom-detection and measurement of bed morphology, and have previously discarded the received acoustic back-scatter from the water column after the bottom-detection algorithms have been performed. However, modern data handling and storage technologies have facilitated the logging of this large quantity of acoustic intensity and phase information, and commercial MBES systems are now available that provide this capability. This paper develops a novel methodology to exploit this logging capability to quantify the concentration and dynamics of suspended sediment within the water column. This development provides a multi-purpose tool for the holistic surveying of sediment transport by imaging suspended sediment concentration, associated coherent flow structures and providing concurrent high-resolution bathymetry. This paper presents methods of data analysis and results obtained from deployment of the RESON SeaBat 8125 and 7125 MBES systems in the field and during testing in a controlled environment. The field results were obtained from sites on the Paraná river, Argentina, with the aim of examining the dynamics of suspended sediment transport over dune bedforms and in the region of flow mixing between large rivers of significantly different suspended sediment concentration. Controlled testing was performed in a former ship dry-dock by creating flows density currents of known suspended sediment concentration with different types and mixes of sediment. The results demonstrate the capability of the RESON MBES systems to successfully resolve the contrast in suspended sediment concentration, and hence the spatio-temporal monitoring of the associated coherent flow structures. The

  9. [Noise exposure in a dry dock]. (United States)

    Atzeri, S; Vacca, L


    Personal monitoring of noise exposure was conducted in a small dry dock, where mainly tug-boats and high sea fishing-boats are refitted. Manual tools were the prevalent noise sources. Noise exposure could be affected and amplified by factors extraneous to workers' tasks. The workers might be employed in different jobs simultaneously also in confined and small areas, and were mainly involved in non-routine tasks. Six different tasks were investigated: dry-dock supervisor, welder/ship-wrights, painters, electricians, woodworkers and unskilled workers. The number of workers employed in the tasks, with the exclusion of the supervisor, might change from day to day according to the particular work phase carried out on the boat. Daily personal exposure was measured using Larson Davis mod. 700 integrating sound level meters. The all shift time history of short equivalent continuous sound level with 10 s integrating time was collected for each selected worker. A 1/2 inch microphone was attached to the helmet at a distance of 11 +/- 1 cm from the right outer ear. Measurements were repeated over 13 days and randomly distributed over about four months. The number of data-points collected was nine for the supervisor, twenty-seven for the welders, eighteen for the painters, twelve for the electricians, six for the woodworkers and eleven for the unskilled workers. Ranges of the daily noise exposure level were from 15 to 30 dBA for all tasks, with the exclusion of the woodworkers. The time histories relative to workers grouped in the same task were matched to verify the correlation. The daily exposure levels derived from correlated samples were substituted by their arithmetic mean. The analysis of variance applied to experimental distributions of daily exposure for four of the welders indicates that the difference of means (p > 0.3) is not significant. A similar conclusion is reached for painters when only this task is considered. If we take into account the exposures of painters