Crew And Supply Boat Conversion Can Be A Profitable Venture

Free Technical Paper Offered Supply vessels and crewboats are the lifeline of the offshore oil and gas industry. These sturdy vessels perform a multitude of functions, from carrying potable water and fuel oil to valuable deck cargoes and important operating personnel.Due to the reduced level of activity in the offshore industry, many of these versatile vessels have become available for other uses.

The following article is based on a technical paper, "Alternate Applications of Surplus Offshore Support Vessels," presented by Anil Raj, director, support services, and John Moreau, engineering manager, Trinity Marine Group, at a recent Gulf Coast Society of Naval Architects and Marine Engineers (SNAME) meeting in Pascagoula, Miss.

Trinity Marine Group operates Halter Marine Shipyards at Lockport, La. and Moss Point, Miss., Moss Point Shipyard, Moss Point, Miss., Equitable Shipyards, at New Orleans and Madisonville, La., and Gretna Machine & Iron Works, Harvey, La.

Applications For Supply Vessels Supply vessels, which usually range from 110 to 225 feet long, are characterized by pilothouses, accommodations forward and large clear decks aft. These shallow-draft vessels often have single or doublechined hulls, which provide superior roll damping characteristics. They lend themselves to simple and economical conversion, primarily because of their large open deck aft, which permits: (1) easy access to the engine room for repowering or refitting of machinery; (2) modification, conversion or removal of tanks below deck; (3) erection of additional accommodations or superstructure modification; (4) addition of special mission-related equipment such as cranes or winches; and (5) use of the available space for alternate cargoes such as containers.

In addition, large freezer and reefer spaces once used for transporting perishables, can be used to increase the vessel's galley services for a larger crew. Because of their relatively square midbodies, supply boats are simple to jumboize.

One example of an alternate use, is the conversion of a 224-foot tug/ supply vessel into the first U.S.-flag surimi catching/processing vessel.

The conversion operation involved the addition of a large shelter deck with a built-in stern ramp and the covering of the weather deck. A Flume stabilization system was added to suppress roll and maximize working time for the processing crew. Gantries for trawl gear handling, freezer holds, a fresh-water distilling system, telescoping cranes as well as various electronics and hydraulics were added to complete the conversion. The shelter deck area houses a complete processing factory, including machines for heading, gutting, filleting and skinning fish. The on-board Surimi processing line converts the catch to a paste-type substance for the making of imitation crab, scallop and shrimp products.

A second conversion example is the modification of a supply vessel for Military Sealift Command rollon/ roll-off (RO/RO) service. The work involved the addition of a large midbody as well as a stern ramp for loading and discharge operations.

Conversion to a cruise vessel is another viable alternative for a supply vessel. In one example, electrical capacity of the vessel was increased through the addition of generators to handle the increased power loads imposed by passenger service.

Sound dampening materials were added to reduce noise levels and superstructure and fashion plate were fitted to incorporate the details of a much larger cruise liner.

Proven applications in other ma- rine areas include conversions for: national defense and drug trafficking interdiction; seismic; diving support; subsea maintenance; remotely operated vehicle support; vehicle and passenger ferry service; manned submersible support; and crab processing/ catching.

Applications For Crewboats Ranging in size from 35 to 125 feet overall, crewboats are generally built of light gauge steel or aluminum, in single and double-chined hull configurations. They are almost always planing crafts. Since crewboats are primarily offshore passenger ferries, boasting high maneuverability and speed, they naturally lend themselves to passenger ferry service.

In addition, their high speeds, rugged construction and good seakeeping characteristics make them suitable for conversion for military, patrol boat and search-and-rescue applications.

Although crewboats may not be as cosmetically appealing as yachts, some slight modifications can easily convert them to this type of service.

Wide open passenger spaces allow the installation of additional and luxurious accommodations including lounge areas.

Other converted crewboat applications include: offshore charter fishing, oil spill clean-up operations, pilot boats, pleasure cruise vessels, single-point mooring assist, line handling vessels and a variety of launches and ferries.

For example, one crewboat was converted to a fisheries partol boat for a foreign government. The quarters were equipped for extended operations.

Gun mounts and extensive electronic surveillance equipment were added.

In another recent conversion, a 122-foot crewboat was modified for passenger ferry service. The passenger capacity of the vessel was increased from 94 to 250, and extra power generation was added to handle increased power loads.

Other proven applications include conversion to pilot launches, single point mooring assist and pollution control vessels, line handling vessels and pleasure craft.

Converting and modifying crewboats and supply vessels for dozens of alternate operations is just good common-sense business. It adds up to lower costs for the vessel owners, more work for shipyards and additional business for manufacturers of every conceivable type of equipment required, including everything from complete repowering, electrical generation, air conditioning, new navigation, communications, safety and sanitary equipment to new filters, bearings, paint and passenger accommodations.

For free copies of the full technical paper presented by Mr. Raj and Mr. Moreau and complete details regarding the full range of vessel conversion, new construction and reapir services offered by Trinity Marine, Circle 89 on Reader Service Card

Other stories from June 1988 issue


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