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PROPULSION
The propulsion of a boat determines many of the operational characteristics
of the boat.
- Outboard - self-contained gasoline powered propulsion system. Power and transmission contained in one housing. The outboard is attached to the boat transom. The engine(s) act as a rudder when swiveled left or right by wither a tiller or steering cables connected to a steering wheel.
- Inboard – an engine (gas or diesel) mounted inside the hull, usually along the centerline. Provides power and the transmission in the same unit. Transmission is connected to a drive shaft that exits through a hole in the hull (through-hull fitting). A propeller is connected to the end of the drive shaft. Steering is made possible by a separate rudder located behind (aft) the propeller. The rudder is attached to the to the hull and steering cables connect it to the steering wheel. It swivels left or right as the steering wheel is turned, redirecting water and turning the boat.
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Outboard Engines |
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Stern Drive |
- Inboard/Outboard , commonly referred to as an “I/O” or “Stern-Drive” – Engine mounted inside the boat, while the gearbox and propeller (lower unit) are mounted outside the hull. The I/O system eliminates the need for a separate rudder since the lower unit swivels left or right as the wheel is turned to provided steering capabilities.
- Jet-Drive – inboard gasoline engine that uses a drive shaft connected to an impeller (similar to a propeller in design, but contained inside a housing). As the impeller spins, it grabs water coming through an intake area and forces the water through a steerable nozzle to provide thrust and steering. Examples of jet drive boats are Personal Watercraft (PWC) and Jet Boats. Jet drives units can also be attached to outboards instead of the traditional propeller.
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Steerable Nozzle |
- Human Powered Craft – manually oared by a person(s). Examples are canoes, kayaks, and paddleboats.
- Sailing – uses sails to capture the force of the wind and propel the boat.
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