Vessel Hull Research Articles

A method for magnetic field prediction caused by naval vessels using magnetic charge distribution

From the viewpoint of equivalent sources, the ferromagnetic hull of naval vessels is regarded as a magnetic charge layer, and a Fredholm integral equation of the first kind relating the layer with the measurements of magnetic field sensors is developed. After the discretization of the integral equation, a system of linear equations is obtained which is solved by generalized inverse matrix, and the condition number is employed to assess whether the system is ill-posed. Then the field caused by the hull at an arbitrary point in the space is predicted by the calculated layer. A numerical simulation shows that our method can precisely identify the magnetization to predict the field. And finally a ship model is used to verify the method.

A survey of antifoulants in sediments from Ports and Marinas along the French Mediterranean coast

Due to deleterious effects on non-target organisms, the use of organotin compounds on boat hulls of small vessels (<25 m) has been widely prohibited. The International Maritime Organisation (IMO) resolved that the complete prohibition on organotin compounds acting as biocides in antifouling systems should commence in 2008. As a result of restrictions on the use of organotin based paints, other antifouling formulations containing organic biocides have been utilised. This survey was conducted to assess the contamination of replacement biocides in the marine environment following the ban of TBT-based paints. Surface sediments samples were collected in the major ports and marinas along the France Mediterranean coastline (Cote d’Azur) and analysed for organotin compounds, Irgarol 1051, Sea-nine 211 TM, Chlorothalonil, Dichlofluanid and Folpet. Every port and marina exhibited high levels of organotin compounds, with concentrations in sediments ranging from 37 ng Sn g −1dry wt in Menton Garavan to over 4000 ng Sn g −1dry wt close to the ship chandler within the port of Villefranche-sur-Mer. TBT degradation indexes suggested that fresh inputs are still made. Among the other antifoulants monitored, only Irgarol 1051 exhibited measurable concentrations in almost every port, with concentrations ranging from 40 ng g −1dry wt (Cannes) to almost 700 ng g −1dry wt (Villefranche-sur-Mer, ship chandler).

Marine ecosystem acoustics: contributions of sonar technology

Sonar is considered in the widest sense as an acoustic system consisting of a transmitter and receiver of underwater sound. It may be monostatic, bistatic, or multi‐static; narrowband or broadband; with one or more fixed, rotating, or electronically formed beams. Transducers may be mounted on hulls of vessels and autonomous underwater vehicles, fixed structures, or seafloor; towed; or suspended. Spatial scales may be sampled from millimeters to thousands of kilometers; corresponding temporal scales vary from a fraction of a second, as in target‐tracking, to seasons, as in observing animal migration. Several sonar types are described. Contributions of sonar technology to ecosystem studies, both actual and potential, are noted. These include, for example, fine‐scale surveying of pelagic and semi‐demersal fish by scientific echo sounder; mapping of the three‐dimensional structure of fish aggregations and bathymetry by multibeam sonar; quantification of benthic egg beds of the squid Loligo opalescens by sidescan sonar; and large‐scale surveying of swimbladdered fish by parametric sonar. Each of these sonar systems has potential for detection, quantification, and classification of marine organisms, as well as for characterization of the habitat, hence yielding the kind of information that is required for ecosystem assessment and management.

Determinants of the damage cost and injury severity of ferry vessel accidents

This study investigates determinants of the property damage cost and injury severity of ferry vessel accidents. Detailed data of individual ferry vessel accidents for the 11-year timeperiod 1991–2001 that were investigated by the U.S. Coast Guard are used to estimate ferry-vessel accident property damage cost and injury severity equations. Tobit regression is used to estimate the former equation and the ordered probit model is used to estimate the latter. Property damage costs include damage costs to the vessel itself, its cargo and contents, and other-property damage (e.g., damage to pier structures and waterfront facilities). Injury severity for a ferry vessel accident is measured as an ordinal variable — no injuries, non-fatal injuries and fatal injuries. Damage cost and injury severity of individual ferry vessel accidents are expressed as functions of the type of vessel accident, vessel characteristics, vessel operation phase, weather/visibility conditions, type of waterway, type of vessel propulsion, type of vessel hull construction and cause of vessel accident. The property damage estimation results suggest that allision, collision and fire ferry vessel accidents incur more vessel property damage cost per vessel gross ton than other types of accidents. The injury severity estimation results suggest that injury severity is greater when the ferry vessel accident is caused by human error as opposed to vessel and environmental factors.

Management options for vessel hull fouling: an overview of risks posed by in-water cleaning

Abstract Hopkins, G. A., and Forrest, B. M. 2008. Management options for vessel hull fouling: an overview of risks posed by in-water cleaning. – ICES Journal of Marine Science, 65: 811–815. Hull fouling has been identified as an important pathway for the spread of non-indigenous marine species. However, the management of associated biosecurity risks has proven challenging. Left unmanaged, a fouled vessel can pose a biosecurity risk through the detachment and dispersal of viable material, and through spawning by adult taxa upon arrival in a recipient port or region. These risks can be managed effectively through the removal of the vessel to land for defouling (e.g. dry-docking). However, alternative methods are needed for small (e.g. recreational) vessels, as well as for large vessels fouled outside their dry-docking schedule. Among the various treatment options, in-water cleaning is relatively common, although some countries have placed restrictions on this method because of perceived biosecurity risks. Here, we present a conceptual framework that identifies risks posed by in-water cleaning compared with alternatives, including no management. Decisions on the appropriate management option will be influenced by many factors, including the species present, the level of fouling, and the time a vessel spends in a recipient region. It is important that any regulatory changes regarding in-water defouling be supported by relevant research that quantifies the risks associated with the various management options.

The potential for translocation of marine species via small-scale disruptions to antifouling surfaces

Vessel hull fouling is a major vector for the translocation of nonindigenous species (NIS). Antifouling (AF) paints are the primary method for preventing the establishment and translocation of fouling species. However, factors such as paint age, condition and method of application can all reduce the effectiveness of these coatings. Areas of hull that escape AF treatment (through limited application or damage) constitute key areas that may be expected to receive high levels of fouling. The investigation focused on whether small-scale (mm2 to cm2) areas of unprotected surface or experimental ‘scrapes’ provided sufficient area for the formation of fouling assemblages within otherwise undamaged AF surfaces. Recruitment of fouling taxa such as algae, spirorbids and hydroids was recorded on scrapes as narrow as 0.5 cm wide. The abundance and species richness of fouling assemblages developing on scrapes ≥1 cm often equalled or surpassed levels observed in reference assemblages totally unprotected by AF coatings. Experiments were conducted at three sites within the highly protected and isolated marine park surrounding Lady Elliott Island at the southernmost tip of the Great Barrier Reef, Australia. Several NIS were recorded on scrapes of AF coated surfaces at this location, with 1-cm scrapes showing the greatest species richness and abundance of NIS relative to all other treatments (including controls) at two of the three sites investigated. Slight disruptions to newly antifouled surfaces may be all that is necessary for the establishment of fouling organisms and the translocation of a wide range of invasive taxa to otherwise highly protected marine areas.

Gross and Histologic Evidence of Sharp and Blunt Trauma in North Atlantic Right Whales (Eubalaena glacialis) Killed by Vessels

Vessel-whale collision events represented the ultimate cause of death for 21 (52.5%) of the 40 North Atlantic right whales (Eubalaena glacialis) necropsied between 1970 and December 2006. Injuries seen in vessel-struck whales fall into two distinct categories: 1) sharp trauma, often resulting from contact with the propeller, and 2) blunt trauma, presumably resulting from contact with a vessel's hull. This study analyzes four trauma cases that resulted from vessel-whale collisions, which together provide a framework for a more critical understanding of lethal blunt and sharp trauma resulting from vessel collisions with right whales. In case no. 1, contact with a propeller resulted in three deep lacerations. The animal survived acute trauma only to succumb nearly 14 years later when the lesions reopened and became infected. In case no. 2, anecdotal reports linked the laceration of large arteries of the peduncle and histologic evidence of perimortem trauma at a bone fracture site to vessel-whale collision trauma. Case no. 3 had a laceration of the oral rete and a fracture of the rostrum. Both of the areas displayed histologic evidence of perimortem blunt trauma. Finally, in case no. 4, an antemortem mandibular fracture, two additional skull fractures, and widespread hemorrhage were consistent with severe blunt trauma. Evidence from each case, including the timing of trauma relative to the time of death and identifying characteristics of both trauma types, are presented. Before this study, no detailed comparative analysis of trauma pathology that resulted from lethal interactions between vessels and right whales had been conducted. This study demonstrates the importance of detailed gross and histologic examination in determining the significance and timing of traumatic events. This work represents a new paradigm for the differential diagnosis of lethal sharp and blunt trauma in right whales hit by ships and will enhance the present understanding of the impact of anthropogenic mortality on this critically endangered species.

A system for measuring mechanical stresses in a vessel hull

Sensors of the stressed state of hulls and systems that gather and process information from those sensors play a special role in the monitoring of the strength of vessel structures. Magnetoelastic transducers are the type of sensors that are most suitable for this purpose. This study is devoted to the development of a system for monitoring the stressed state of a vessel hull that meets the modern requirements of norms and rules regarding the monitoring of the stressed state of a vessel hull. The proposed monitoring system incorporates a unit for digital processing of signals and mandatory recording of the measurement process. The system was developed taking into account marine conditions; issues of technical maintenance and the cost of the proposed project were also considered. Options for the use of the mathematical regression method in monitoring of stresses in hull structures of vessels are analyzed. Approaches to the development of the system for monitoring stresses in hulls are outlined.

Vessel hull transducer modular mounting system

A vessel hull transducer modular mounting system enables transducers to be replaced and upgraded without necessitating the further modification of the hull and thus not necessitating the dry-docking of the vessel. A further feature includes the ability to reduce and dampen acoustic shock impact on the transducer. Another feature includes the ability to extend and retract the transducer which can operate in bottom scan, forward looking, side scan, searchlight, and sweep modes.

Optical underwater acoustic sensor

An acoustic sensor used in underwater applications. The sensor includes a reflective material adhered to a structure, such as an outer submarine hull or any marine vessel hull. A laser interferometer is placed on the side of the structure with the reflective material. The laser interferometer sends a plurality of laser beams, in sequence or all at one time, to a plurality of points across the retro-reflective material. The laser beams reflect back to the interferometer, which captures the reflected beams using receiving optics. The phase modulation of the reflected laser beams is compared to a reference laser beam within the interferometer to obtain the vibration velocity characteristics of the hull surface structure. Since the reflective material is adhered to the structure, the structure vibration is the same as the vibration of the reflective material. From this vibration, the acoustic pressure associated with the structure may be calculated.

Identification of hydro-acoustic waves emitted from floating units during mooring tests

Identification of hydro-acoustic waves emitted from floating units during mooring tests Measurements of hydro-acoustic noise emitted from vessels are a.o. a subject of the tests carried out in the control measurement ranges of the Navy. The measurements are performed both on anchored and floating vessels. Acoustic field of vessels is changing along with their speed changing and is associated with acoustic activity of wave sources installed in vessel's hull (main engines, electric generating sets, reduction gears, pumps, shaft-lines, piping, ventilating ducts etc) as well as hydro-dynamic sources such as screw propellers and water flow around the hull [5, 7]. Vibration energy generated by the onboard devices is transferred through ship structural elements to water where it propagates in the form of hydro-acoustic waves of a wide frequency band.

The invasive Asian Green Mussel, Perna viridis (Linnaeus, 1758) (Bivalvia: Mytilidae), breeds in Trinity Inlet, tropical northern Australia

In August (dry season) of 2001, the Asian Green Mussel, Perna viridis (Linnaeus, 1758), was found in high densities on the hull of a foreign vessel moored within Trinity Inlet, northern Queensland, Australia. Surveys conducted between late 2001 and July 2003 in response to this invasive marine pest detected mussels on other floating structures throughout the Inlet, indicating at least one spawning and successful recruitment event had taken place in the Inlet between 2001 and 2003. At the completion of surveys in July 2003, a total of 40 recruits with a range of 30.1 mm to 161.0 mm shell length (mean 95.0 mm shell length) had been recovered from the Inlet. At least four additional recruits from this Trinity Inlet population are known to have been translocated to Innisfail 90 km south of Cairns on the hull of a yacht during this period.

Application of fuzzy neural networks for the data clusterization problem

The fuzzy neural network for pattern clusterization is described. The network training is based on c-means algorithm. An original methodology for the statistical interpretation of result of c-means clusterization is proposed. As an example, the clusterization of vessel hull tenzo measurements on the arctic route. An approach to preprocessing of the raw measurements for the further usage by means of the described methods is discussed.

Experimental Validation of a Marine Propeller Thrust Estimation Scheme

A thrust estimation scheme for a marine propeller has been experimentally tested in waves and with a device that simulates the influence of a vessel hull. The scheme is formed by a nonlinear propeller torque observer and a mapping to generate the thrust from the observed torque. The mapping includes the estimation of the advance number. This is utilized to improve the performance when the propeller is lightly loaded. The advance speed is assumed to be unknown, and only measurements of shaft speed and motor torque have been used. Accurate results have been obtained in experimental tests.

Novel method for assessing the en route survivorship of biofouling organisms on various vessel types

Shipping is considered the single largest vector fo rthe human-mediated movement of non-indigenous marine species (NIMS) around the world. A variety of shipping mechanisms are capable of transporting NIMS to new locations. Biofouling or hull fouling is now being acknowledged as one of the single most important dispersal mechanisms alongside ballast water. Little is known of the factors that contribute to en route survivorship of biofouling. This study presents a novel method for attaching settlement plates to vessel's hulls for the empriical assessment of en route survival.

The Vessel Hull Design Protection Act of 1998: is it still afloat?

Legal context. The Vessel Hull Design Protection Act (‘VHDPA’ or ‘Act’) is a unique form of industrial design protection under US law, part of the Digital Millennium Copyright Act 1998. Congress provided this sui generis form of protection in response to the Supreme Court's decision in Bonito Boats v Thunder CraftBoats, Inc. This statute has been underutilized due to the difficulty in proving infringement, as unintended consequences were caused by the way ‘hull’ was originally defined under the Act. A bill is pending in Congress that addresses how a ‘hull’ is defined, eliminating any inclusion of ‘deck’ features, when passed, registrants should be able to pursue infringers with greater success. Key points. The recreational boat manufacturing industry has been plagued by low-cost boat makers who think nothing of taking a competitor's boat hull design, and using it as a ‘plug’ to make a casting for their own unauthorized manufacturing use, a counterfeiting technique known in the trade as ‘splashing’ a hull. In the eight years since enactment, the boating industry has generally overlooked this form of intellectual property protection due to the difficulty in proving infringement—that is likely to change soon. Practical significance. The Act includes the right to exclude others from making, having made, importing, offering for sale, or using in any trade, any boat hull embodying the protected hull design. The Act provides compensatory recovery for damages as well as injunctive relief. The newly revised Act has the potential to provide a low-cost and effective form of intellectual property protection for recreational boat manufacturers who build hulls from moulded fibreglass or similar materials.

Differential resistance to extended copper exposure in four introduced bryozoans

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 311:103-114 (2006) - doi:10.3354/meps311103 Differential resistance to extended copper exposure in four introduced bryozoans Richard F. Piola*, Emma L. Johnston School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia *Email: r.piola@unsw.edu.au ABSTRACT: Resistance to copper by some fouling species may have the 2-fold effect of both facilitating the introduction of nonindigenous species via the painted hulls of vessels, and providing these species with a competitive advantage in ports or estuaries already exposed to anthropogenically elevated copper concentrations. This study tested the tolerance of 4 introduced bryozoans, Bugula neritina, Watersipora subtorquata, Schizoporella errata and Tricellaria occidentalis, to a range of Cu concentrations (0, 10, 50, 100 and 500 µg l–1). Larval attachment after 24 h was not found to be a reliable indicator of post-metamorphic survival. Recruits of all species survived in 0 and 10 µg l–1 Cu for 20 d, with only Bugula neritina and Watersipora subtorquata recruits surviving exposure to 50 and 100 µg l–1 Cu. B. neritina and W. subtorquata colonies exhibited reduced post-metamorphic growth in 50 µg l–1 Cu compared to controls, with no growth observed in 100 µg l–1 Cu. Growth for S. errata and T. occidentalis was higher at 0 µg l–1 than 10 µg l–1 Cu. Post-exposure growth of surviving colonies was assessed by transplanting colonies to the field. W. subtorquata colonies exposed to 50 µg l–1 Cu were the only colonies to show decreased survival and growth post Cu-exposure. Overall, B. neritina and W. subtorquata showed the greatest tolerance to Cu. These findings have important implications for the management, control and assessment of invasion potential of these invasive marine hull-fouling species. KEY WORDS: Cu · Attachment · Post-metamorphic survival · Post-metamorphic growth · Antifouling paint · Tolerance · Introduced species · Hull fouling Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 311. Online publication date: April 13, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.

An in vivo study of exocytosis of cement proteins from barnacle Balanus improvisus (D.) cyprid larva

Barnacles, like many marine invertebrates, cause serious biofouling to marine industrial constructions and hulls of vessels as they attach themselves to such surfaces. Precise biochemical understanding of the underwater adhesion to surfaces requires a detailed characterization of the biology of the control of barnacle cement secretion and the proteins that make up the cement. In this study, we have investigated cement secretion by cyprid larvae of Balanus improvisus (D.) and the morphology of their cement glands. We studied the cement protein organization within cement granules and categorized the granules into four different types according to their size and morphology, before and after stimulation of secretion. In addition, we followed the exocytotic process of cement secretion in vivo and discovered that granules undergo a dramatic swelling during secretion. Such swelling might be due to an increased osmotic activity of granule contents, following a process of hydration. We hypothesize that this hydration is essential for exocytotic secretion and conclude that cement protein exocytosis is a more complex process than previously thought and is similar to exocytotic secretion in vertebrate systems, such as histamine secretion from mast cells and exocrine secretion in the salivary gland and the pancreas.

Establishment of the Caribbean Serpulid Tubeworm Hydroides sanctaecrucis Krøyer [in] Mörch, 1863, in Northern Australia

The serpulid tubeworm Hydroides sanctaecrucis is recorded from tropical northern Australia for the first time. This species is native to the Caribbean, where it is common in coastal lagoons, and has not previously been reliably recorded from the western Pacific. The species was identified after heavy and unusual serpulid fouling was noted on vessel hulls in Cairns, north Queensland, and hull fouling is considered the most probable vector for its translocation to the western Pacific. In northern Australia, H. sanctaecrucis displays similar traits to other fouling and now widely dispersed fouling serpulids such as Hydroides elegans, H. ezoensis and Ficopomatus enigmaticus.

Propulsion shaft alignment method and analysis for surface crafts

This paper presents an approach to determine the changing displacement of the propulsion shaft due to the vessel's hull deflection. The model considered is a 60 m long shafting system of a ship consisting of 10 bearings, one gearbox and one main engine. This paper presents a comprehensive alignment analysis process for a long shafting system. A deflection analysis program, Shaftflex, is to shorten the analyzing time and to maintain consistency in the analysis process. Alignment of the first four bearings, which are exposed to the sea, has to be determined first and while on the launch way. As the ship hull is flexible, hogging occurs when it is afloat. It is observed that there is an inherent upward tilting of the shaft as such pre-tilting the projected shaftline downwards is necessary in order to counter the problem. Furthermore, as the shaft is more flexible than the ship's hull, it will be able to deflect as much as the hull and as a result causing variation in the loading at bearings. Therefore, the hull deflection characteristic of a vessel is a major concern in the analysis and alignment of a long shaft system. It is found that the alignment of the first four external bearings greatly affects vertical position of the gearbox and the main engine, which are aligned afloat and taking reference from the bearings. Numerical algorithm is also developed for such an analysis. The work presented in this paper is based on analytical geometry, arithmetic and trigonometry expressions. The derived mathematical expressions are incorporated into commonly used and comprehensive software for a quick analysis and parametric study.