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FRF Vehicles
Coastal Research Amphibious Buggy (CRAB)

The unique three-wheeled vehicle, the CRAB was built by the Wilmington District of the US Army Corps of Engineers, and was modeled after a vehicle originally built by Marine Travelift & Engineering of Sturgeon Bay, for the Great Lakes Dredge and Dock Company, to monitor a Corps of Engineers beach nourishment project.

The CRAB consists of a tripod of 0.2 m schedule-80 aluminum tubing, connected at the base by horizontal members 2.1 m (7 ft) above the ground, and an operations platform 10.7 m (35 ft) above the ground. Power is supplied by a 60-hp turbo charged Volkswagen diesel engine on the deck which drives a variable volume hydraulic pump. This pump transfers hydraulic fluid at 800 psi or higher to hydraulic motors at each of the wheels. The variable stroke feature of the pump allows an infinitely variable gear ratio in either forward or reverse and constant engine speed. For strength and corrosion resistance, all hydraulic lines are stainless steel, except for short flexible sections at the front wheel, which is used for steering.

Total vehicle weight is about 8,200 kg (18,000 lb); the distance between the rear wheels is 8.2 m(27 ft). Though it appears top-heavy, the liquid-filled tires and wide wheelbase make it very stable. The CRAB has passed a 20-deg tilt test and is designed to withstand even steeper angles.

Top speed of the CRAB is 3.2 km/hr (2 mph) on land and somewhat less in the water. Since the maximum significant wave height for operation is 2 m (6 ft), the CRAB is capable of operating in all but the most severe storms. The large tires have a negligible effect on a hard rippled sand bottom; however, scour around the tires has been observed in areas of active wave breaking or strong currents if the CRAB remains motionless. The CRAB cannot be used on soft silty or loose bottoms. The position of the CRAB is determined by a Trimble 4000 SSE GPS. Recently the Dutch have built their own version of the CRAB called the WESP

Click to view a CRAB Video. Movie viewers may be obtained from www.real.com


The LARC-5 (Lighter Amphibious Resupply Cargo) is an Army amphibious vehicle that is used to deploy instruments, support diving activities, collect data, and tow a variety of sensor and survey "sleds". The offshore operating range is 8 km (5 mi). An onboard crane can lift 400 kg (900 lb) and its total possible load is 5 tons (hence the five after LARC.) The LARC's maximum speed is typically 5 knots in the water and 18-20 mph on the road. The Army used the LARC to ferry supplies from boats to shore; when purchased by the FRF, our LARC was military surplus.

Click to view a LARC Video.Movie viewers may be obtained from www.real.com

• For more information about the LARC Survey System click here.

Sensor Insertion System (SIS)

This crane-like device is able to reach from 50-75 feet out from the side of the pier and is capable of rapidly deploying instruments anywhere along the pier because it is on railroad tracks mounted on the deck. Measurements can be made even during wave heights up to 18 feet and in winds up to 49 mph. Precision positioning allows delicate instruments to be situated within inches of the seabed without diver assistance.

Instruments to measure the waves, currents, and sediment movement are mounted on the boom of the SIS and lowered into the water. Some of these instruments are pressure gauges, current meters, and sediment transport sensors. These data are important to coastal engineers because very little is known about how sand is moved during storms, and it is during big storms that significant beach erosion takes place. The SIS is also an ideal tool for testing and evaluating different instruments.

Click to view a SIS Video.Movie viewers may be obtained from www.real.com

All-Terrain Forklift

The FRF's all-terrain forklift has a 2700 kg (6000 lb) lift. It is used for carrying instruments, cables, and boats to the beach.