There's a lot of talk out there about personal hovercraft material and construction techniques which tend to focus on the skirt and the hull, which of course have undergone big changes over the past 6 or 7 years, but the all-important engines are often not talked about, or at least, not extensively. In the past, large passenger hovercraft were driven by multiple engines. Huge ones for proving lift and slightly smaller ones for forward thrust. The RN101 hovercraft which first saw service across the British Channel in the 60s, had four massive Rolls Royce engines mounted and equally spaced across the deck, one in each corner of the air cushioned craft.
Several more Roll-Royce state-of-the-art engines were hoisted well above the deck at the rear and drove the monster at about 100 kmph. The noise must have been formidable and it rocked around a lot - the channel can be very choppy indeed. The Russian monster Zubr class hovercraft is the biggest yet ever built and has 7 engines. Three high temperature gas turbine engines are shrouded at the rear of the craft and four are used for creating lift for the air cushion. This monster can carry up to 400 troops and 20 tanks within it's cargo hold.
Small personal hovercraft may have one or two engines, depending upon payload which means number of passengers and equipment combined - more here Hovery Leisure Hovercraft . This figure is very important t ensure that there is enough power to lift the hovercraft off water when fully loaded - this is called getting over the hump and is a critical test of hovercraft efficiency. Paradoxically, it takes about 30% of the power required to lift a helicopter of equivalent weight, but three times the hovering power to get over the hump when resting on water. Generally, hovercraft over 6 seats have two engines, one for lift and one for forward thrust.
Finally, there is a choice of the kind of engine you can have when you buy a hovercraft. The smaller variety craft can have either two stroke or four stroke engines. Two stroke are cheaper, but the four stroke are more powerful for the same weight and smoother. Neither of these are water cooled, as the goal is keep all systems as simple as possible. An exciting third option is now appearing for some lighter craft such as the Hovery, which is an inflatable craft designed by a Brazilian pilot, and that is an electric motor.