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First Foil Supported Patrol Boat In U.S. Service.

The U.S. marine community is closely watching the performance of the P/V Thresher, a 55 ft. patrol boat for the California Department of Fish & Game operating between the Mexican border and Santa Barbara County, Calif., including the channel islands and offshore fishing banks. Built by Seattle's Kvichak Marine Industries, the P/V Thresher is the first foil-supported catamaran operating in U.S. waters.

Speed and stability were requirements when the department began planning a new patrol boat. "So far, the vessel is incredibly stable," said Lt. Chris Graff, skipper of the P/V Thresher. "The vessel rides well in broadside seas. It sometimes took six or seven men to launch a skiff in bad weather in our former conventional patrol boat. Now we can do it with our three-man crew."

Twin Caterpillar 3196 DITA engines each deliver 660 hp at 2300 rpm. The engines drive 30 in. Nibral propellers through Twin Disc MG 5114A 1.92:1 ratio marine gears and 2.5 in. diameter Aquamet 22 propeller shafts. The vessel has a top speed of 30 knots and cruises at 25 knots.

The engines are fitted with 60A 24 Vd.c. alternators, auxiliary front pulleys, lube oil change pumps, block heaters, alarm systems and instrumentation. Engines and exhaust pipes are heat exchanger cooled.

Primary 24 Vd.c. electrical power is provided by six 210-amp-hr, 8D batteries, located in the port engine space and controlled by vapor-tight selector switches. A console mounted breaker panel distributes power to on-board electrical equipment. An auxiliary 12 Vd.c. circuit is controlled by a breaker panel and energized by two 24 Vd.c. to 12 Vd.c. power converters.

A Northern Lights 12 kW diesel generator set provides 220/120 Vd.c. single-phase power, while a 7.5 kW Onan generator provides standby. Both generators employ wet exhausts using Centex mufflers and are enclosed in sound shields.

Start and stop controls are provided at two control stations, the wheelhouse and the flying bridge. Engine throttle and shift controls involve a Hynautic manual hydraulic system actuated by shift and throttle levers at each control station.

The steering system is actuated by a manual steering system with 20 in. diameter steering wheels at each station.

The vessel carries two aluminum 400 gal. and two 200 gal. diesel fuel tanks. Fuel flow is controlled by ball valves mounted on dual Racor fuel filters. Fuel can be transferred forward or aft as well as port to starboard through the use of fuel transfer pumps.

The P/V Thresher is served by six independent 2000 gph bilge pumps. A single pressure-compensated, load-sensing hydraulic pump is mounted to the front end of the starboard main engine and powered via a cardan shaft and 24 Vd.c. electric clutch. The pump powers the 12 in. crab block, crab block davit, a drum-type anchor winch, a pair of A-frame cylinders and an A-frame hoisting winch for handling the Hurricane inflatable. Fluid is supplied by a 20-gallon reservoir in the starboard engine space. The pump provides 15 gpm at pressures up to 2400 psi.

Engine combustion air enters through side-deck intake ducts, baffled to prevent water entry. A pair of 24 Vd.c. blowers in engine spaces serve the air intakes.

The fresh water system involves two 150-gallon polyethylene tanks pumped by either a 24 Vd.c. Jabsco pump or a 120 Va.c. Jacuzzi #1 RM2 through an accumulator. There is also a 30 gal. drinking water tank operated by a foot pump in the galley. A 20 gal. water heater using waste engine heat or 120 Va.c. supplies the hot water

Machinery spaces were treated with 1.25 in. thick sound coat insulation. Sound transmission is limited to 85 dB(A) at cruise rpm in the main cabin.

The P/V Thresher measures 58 ft. long. It has a beam of 20 ft. 2 in. and has draft of 4 ft. 6 in.
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Title Annotation:P/V Thresher from Kvichak Marine Industries
Comment:First Foil Supported Patrol Boat In U.S. Service.(P/V Thresher from Kvichak Marine Industries)
Author:Clevenger, Mark
Publication:Diesel Progress North American Edition
Article Type:Brief Article
Geographic Code:1USA
Date:Sep 1, 2000
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