A jet ski, also known as a water scooter, is an inexpensive recreational watercraft, usually a flat, short-stroke boat the rider stands or sits on, instead of within of, an inboard motorboat. Jet skis are typically used on lakes, rivers and streams; but sometimes (usually in summer) they’re used on dry land as well. Jet skis were developed in the early 1970’s with two major technological achievements: the development of a lightweight carbon fiber body for the boat’s hull and a foam “flue” used to deflect water away from the craft. They’re very effective single-seater water craft, but can also be used as a rowboat, a watercraft scooter and even a diving boat! The latest models of jet skis are very responsive and durable, and are available in numerous configurations, from lightweight models to more powerful versions.
Many popular styles of jet skis use a stand-up ski engine similar to those used on snowboards. Stand-up jet skis (sometimes called stand-up ski engines) are less complex and lighter than traditional inboard engines, making them easier to handle and more versatile. Inboard stand-up engines are more complex and heavier than stand-up jet skis, so the rider is recommended to practice with them on a quiet lake or river before trying them out on the open water. Some manufacturers of stand-up jet skis offer modifications that allow the rider to strap on a leash, much like a boathouse board.
Jet skis have many unique features. One of the most noticeable is that riders can control the direction of the wake by moving the propeller to either side of the craft. This is called a reverse throttle, and it gives the rider several options when he wants to control the wake. If the craft grows too fast, a rider can reverse into a more traditional reverse position, but if it grows slower, he can turn the prop into a top-shelf sail. He can also “turn off” the reverse throttle and allow the craft to slowly go forward; this is called a steady drift. A constant drift allows the pilot to easily return to his original speed and keep the craft in a straight line.
Jet skis are powered by one of three methods, each providing a unique set of advantages. Turbine Engines are mounted behind the craft and drive the propeller shaft into the water exiting the back of the craft. The advantage of this method is that there is little need for training or experience, and the turbine is hidden from sight inside the hull of the boat. This is the most expensive method, because it adds a substantial amount to the boat’s total weight. It also adds an extra engine to the craft, which increases the overall size and cost.
Turbo-Piston Engines are mounted above the craft and are driven by the turbo pump that comes with the engine. Unlike a turbine-driven engine, it does not need a turbine to counterbalance the hull of the boat. This allows it to be positioned in any location possible. With the use of a remote control, riders can adjust the position of the nozzle on the engine and keep it moving in a safe and consistent manner. Though they are faster than turbines, they tend to create less drag, making them less aerodynamic and therefore easier to control. They also do not have the ability to change the water exiting the back of the craft, so when going through turns they must remain in the same direction.
For craft that rely on gravity for propulsion, the best solution is a deflecting propeller, which adds lift to the hull of the boat. Jet ski skis with deflecting propellers are known as “diverters,” and come in two basic types. Water-absorbing and oil-diverting. In a jet skis with a deflecting impeller, the propeller actually pushes the water away from the craft, while leaving the oil itself behind to absorb some of the energy needed to propel the boat forward.
Jet skis with internal or external propellers are attached to the hull by a gearbox or a drive shaft. Internal propellers are not as efficient at generating thrust as the externally designed ones. This is why they are usually mounted on top of the hull, to act as an outlet for the thrust. The advantage of this arrangement is that the internal ski propeller does not need to be responsive, so it can maintain its position even after the craft moves through the water.
External propellers, on the other hand, are connected to the hull by an impeller shaft and a fan. The impeller creates the thrust, while the fan spins the blower fan, which generates the lift. External props have the advantage that they can be used in reverse, as well. If the craft brakes, the pilot can redirect the thrust to the rudder to redirect the direction of the ship. This works best on flat water, but can also be used on lily pads or shallow banks. Using the appropriate type of Jet Ski, a skier can experience all the fun of being in the middle of the ocean, without ever leaving the shore.