Coastal vessel, epic catamaran hovercraft with 2 gatling guns and a SAM.
The first and never surface effect ship designed for the US Navy, the Special Warfare Craft, Medium (SWCM) was conceived in 1982 as a medium-sized patrol boat which could land troops or launch small boats. It was meant to have a high speed and long range, and was meant for the Navy SEALs. Two designs were originally developed, one a standard planing boat, and the other a surface effect ship. Various companies submitted designs, and Rohr Marine, which was already working on surface effect ships but had no prior experience in building ships, was chosen, with the contract awarded in 1984.
The ship was built out of aluminium alloy, and was meant to have more than 90% of its weight supported by the air cushion. The hull was made out of mostly flat panels, meant to reduce costs rather than lower radar signature, and was powered by two diesel engines driving variable pitch propellers, and an air cushion filled by six fans, which could automatically adjust the air to maximize stability. The ship was meant to be armed with two 25mm gatling guns, though for a time was to be provisionally built with two 25mm chain guns instead. Additionally a SAM station with a stinger launcher was provided and there were designs for conversions into a missile boat with Harpoon or Penguin missiles.
Construction started in 1984, with 18 more ships planned. There were issues during construction, the hull was overweight, and the propeller shaft had to be lengthened and put deeper in the water which increased the ships height. Construction was about halfway complete when Rohr Marine filed for bankruptcy in 1986. The funds for the second SWCM was diverted to complete the first, but ultimately it never was. The ship was expended some time later as a target, and would eventually have its role filled by the very standard and safe design-wise Cyclone-class ships.
2x5 25mm EX-35 Sea Vulcan 25 in EX-90 mount (540 round magazines)
2x1 12.7mm M2
1x Stinger MANPAD station
88 tons light
116 tons full
Draft: 2.5m (hull-borne) or 1.6m (cushion-borne)
Propulsion: 2 GM Allison 16V-149T1B + 2 GM Allision 6V-92TA diesel engines, 3600 + 810 hp, driving 2 shafts and 6 Aerophysics SES lift fans, 1080 psi, providing cushion air.
Speed: 35 knots (64.8 km/h)
Electro-optical IR director
Sea Vulcan during testing, the mast behind it mounts the targeting director, funnily enough it was trialed on the SES-200, which would make that the only US Navy surface effect ship ever armed.
Just to clarify what the “Stinger station” is, it’s just a ring with a guy holding a Stinger.
There’s a lot of diagrams, but I don’t understand any of the technical stuff
Model of the Sea Vulcan
An advert of the Sea Vulcan
Friedman, N. (1987). Post-Vietnam Small Combatants. In U.S. Small Combatants: Including PT-Boats, Subchasers, and the Brown-Water Navy: An Illustrated Design History (pp. 402–410). Naval Institute Press.
Lee, C.M. (1986), THE U.S. NAVY SEA VIKING DESIGN DEVELOPMENT HIGHLIGHTS . Naval Engineers Journal, 98: 31-50.
Moore, J. (1988). United States. In Jane’s fighting ships 1987-88 (p. 770). Janes.