This is an 18' Sidewinder jet boat. The pictured boat is a 1973 model year I believe. It's similar to the 1971 Sidewinder that I spent my summers on in the mid 70's, except that Whitey's boat had a blue metalflake finish, and the engine cover was a bit different. The Sidewinder was my first experience with a jet boat. Driving a jet drive takes a bit of getting used to, as they only steer when there is power applied. In fact, it's usually better to "goose" the throttle to "kick" the boat around a turn, rather than turning the wheel over further which can result in the bow "pitching" down in the direction of the turn. Another wild characteristic of a jet, is that you can make it turn 180 degrees while running. You can also make it stop on a dime by sliding it into reverse, which is a simple matter of sliding a gate over the nozzle to divert water flow, rather than having to shift gears in a transmission. A jet also has the advantage of having no drive hardware hanging below the hull which means, if it can float it can run, and in as little as a foot and a half of water.
Ironically, I ran into Whitey's original Sidewinder, up on Lake Wallenpaupack in the early 90's, during on of my trips up there. The new owner had repainted it a two tone red and blue . The interior had been replaced, as had the engine (twice according to the owner) but it still looked good.