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Underwater Technology is the peer-reviewed international journal of the Society for Underwater Technology. The objectives of the journal are to inform and acquaint the Society's members and other readers with current views and new developments in the broad areas of underwater technology, ocean science and offshore engineering.

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Current Issue

Underwater Technology Vol 28 No 3

Summer 2009

A Personal View

Subsea Technology – Where Next?

I Gallett

Technical Papers

The Nereus hybrid underwater robotic vehicle

AD Bowen, DR Yoerger, C Taylor, R McCabe, J Howland, D Gomez-Ibanez, JC Kinsey, M Heintz, G McDonald, D Peters, C Young, J Buescher, B Fletcher, LL Whitcomb, SC Martin, SE Webster and MV Jakubata

Abstract:

The Nereus vehicle will enable scientists to explore remote regions of the oceans, such as under the polar ice caps and deep trenches, up to depths of 10 972m (36 000ft). Technology limitations have prevented routine, cost-effective access to these remote regions, and the final 4500m of the ocean remain largely unexplored. New solutions to deep diving are described. The Nereus hybrid remotely operated vehicle (HROV) is designed for exploration and research needs as a single system. It can operate as an autonomous vehicle for seafloor surveys, or in a tethered/ROV mode to sample rocks or deep-sea animals The HROV Nereus transforms between its two modes of operation to accomplish all these tasks during a single cruise deployment. Sea trials of Nereus took place off the Hawaiian Islands at 2500m in November 2007. An overview of the vehicle and results from its initial trials are reported here.

Technical Papers

Autosub6000: its first deepwater trails and science missions

S McPhail, M Furlong, V Huvenne, J Perrett, M Pebody and P Stevenson

Abstract:

In September 2007 on RRS Discovery, the Autosub6000 autonomous underwater vehicle (AUV) completed its first deepwater engineering trials and, fitted with a multibeam bathymetric mapping sonar, carried out its first science missions less than a year later as part of a geology and geophysics science cruise onboard the RRS James Cook. This paper describes how the issues of energy storage, navigation and buoyancy control were tackled that specifically affect a deep-diving AUV, capable of operating with true autonomy independently of the mother ship.

Technical Papers

A review of sublittoral monitoring methods in temperate waters: a focus on scale

HB Van Rein, CJ Brown and R Quinn

Abstract:

A plethora of methods to monitor shallow sublittoral benthic habitats and communities are available to the marine researcher today. The most widely used methods are reviewed and evaluated, with reference to the spatial scale at which they operate. For ease of comparison, methods are categorised as operating over broad (>1km), meso (10m 1km) and fine scales (<10m). A measure of efficiency and data resolution are provided by exploring the range of sampling techniques and strategies at each of these spatial scales. Recommendations are made regarding which methods are most effective at each scale: light detection and ranging (LIDAR) and multibeam sonar over broad scales; sidescan sonar, drop-down cameras, towed cameras and remotely operated vehicles (ROVs) over meso scales; and grab samplers, sediment corers for soft, unconsolidated sediments and photoquadrats, and video transects for hard, consolidated sediments at fine scales. Emphasis is placed on the development of standardised methodologies for sampling each scale within a nested design, for the monitoring programmes of the future.

Technical Paper

Underwater wet welding made simple: benefits of Hammerhead® wet-spot welding process

D Keats

Abstract:

A new method of wet welding was investigated to evaluate potential improvements in weld quality, ease of use, increased welding speed and the elimination of welding skill. The new welding process, which has been called Hammerhead `wet-spot' welding, eliminates the need for skilled welder-divers as well as traditional cleaning and preparation techniques normally associated with conventional manual metal arc (MMA) wet welding. In addition, the process also allows welding to be conducted in nil visibility, yet remains a MMA process, using a specially designed Fe Cr Ni Mo electrode. The process utilises a control device, which must be pre-set before the diver enters the water. Through this device, weld parameters are controlled and quality is maintained, thus the role of the diver is simplified to three steps: make contact with the material, strike the arc and maintain pressure to the electrode while welding. A series of spot welds were produced both wet and dry on 8.0mm carbon steel plates. The welds were evaluated with regard to ease of use and setting up of the device, speed and final weld quality. Initially, the performance of the process was assessed and usage diagrams produced. Work regarding an automated version of the system has also been proposed.

Meeting Note

Selected Summary Highlights from the 30th Consultative Meeting (LC30) of Contracting Parties to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972 (London Convention 1972) and the 3rd Meeting of Contracting Parties to the 1996 London Protocol (LP3) to the London Convention (London Protocol), 27 31 October 2008 in London at the International Maritime Organization

P Verlaan

Book Reviews

The Andaman Express by Lorne Gifford

Reviewed by I Gallett

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