Skirts and Sidewalls

By 1969 the SR-N4 was carrying 600 passengers on ferry services between England and France at 80 miles per hour (129 kilometers per hour). The ACV fea­tured four gas turbine engines driving airscrews and a tough, flexible skirt to keep the air cushion in place. The skirt also allowed the 160-ton (145-metric – ton) craft to ride over low obstacles without air escaping.

The first ACV skirts were like rubber curtains, and they quickly wore out. The modern ACV has a bag skirt, which looks like a thick tube and is made of
tough nylon and plastic. The craft rests on the bag when it is not moving.

Another type of ACV was developed for use over water only. Known as the sidewall ACV, it has a skirt only at front and back and rigid panels on its sides. The sidewall ACV skims over the water, like a hydrofoil ship, but this type can­not operate overland.