A surface effect ship is also known as a "rigid sidewall hovercraft". There are flexible curtains at the bow and stern to contain an air cushion.
The Navy's experiments culminated in the 1980s with the SES-200:
During the mid-`80s, it was based at Pax River NAS. Quite a few tests were run in the Atlantic, including operations in higher sea states (keeping in mind that, at 200 tons, it wasn't a large ship).
The ride characteristics were different. Going into oncoming seas, the SES-200 tended to knife through smaller waves. But if it encountered a larger wave, the wave would slam against the flat bottom (or the ceiling of the air box, if you prefer). The result was like the ship was punched straight up.
The ship was built and equipped to commercial standards. The radar was a LN-66. Operations were, by necessity, informal enough to drive a tin-can trained officer to drink. There were no gyro repeaters for shooting bearings, so you buoy-hopped and took radar-range cuts to get a position. But when it was riding on its air cushion, it only drew about 5' of water, which is less than a lot of sailboats, so it was harder to get into trouble with it.
There usually were two officers assigned to the ship. It wasn't considered an afloat command, so the boss's designation was "officer in charge". Both officers were post-sea tour warfare-qualified lieutenants (and this was classified as shore duty). If the ship was going out for more than a few days, the commander of the testing operation tried to borrow a qualified officer from another command so that the OODs would be in three sections.
SES-200 was likely the first naval sea-going command to have a female commander, but I don't recollect anyone making a big deal of it at the time.
A few small surface-effect ship test craft were built to conduct research for a 3,000 ton surface effect warship which was thought to be a possible replacement for the Knox class. The SES-3000 program was probably too large of a technological leap, given at the time, not even the SES-200 had been built and the program was axed 35 years ago. One of the 100 ton SES craft fired a SM-2(MR) missile while traveling at over 60 knots.
The Soviet/Russian navy built a couple of 1,000 ton SES warships. That they only built two says something. The Norwegian navy is the only one that has recently built operational SES combat craft.