The hulls get longer and narrower and steps are introduced into the hull to reduce both the pitching and the wetted surface of the hull. The modern high performance deep vee hull is a highly refined design which balances performance and comfort and it can still be competitive in racing against the cats when the going gets rough. The rigid inflatable is really a refinement of the deep vee hull with the air tube introducing new characteristics into the design. Because the tube will deform and change when it impacts with a wave, this has a shock absorbing effect in rough seas, but the tube also gives better stability at rest and makes the RIB one of the best sea boats of its size, and with RIBS now capable of running up to 90 knots they can combine this seaworthiness with speed. The secret of successful RIB operation is not to run with the tubes inflated too hard.
Soft tubes help to cushion the ride.
So the deep vee and the catamaran are the two main types of hull, but a whole host of new concepts has been developed which can be used to modify these basic types. Hydrofoils have been around for a long time and they lift the hull clear of the water so it rides only on the foils. With computer control, these foils can produce an aircraft smooth ride at 50 knots. Then there is the hovercraft where a pressurised air chamber is formed under the hull which lifts it up and reduces the resistance. This can be a full hovercraft which rides only on the air cushion or it can be the SES type where the air cushion is formed between the twin hulls of a catamaran which still stay in the water.