An outboard motor is a propulsion system for boats, consisting of a self-contained unit that includes engine, gearbox and propeller or jet drive, designed to be affixed to the outside of the transom. They are the most common motorised method of propelling small watercraft. As well as providing propulsion, outboards provide steering control, as they are designed to pivot over their mountings and thus control the direction of thrust. The skeg also acts as a rudder when the engine is not running. Unlike inboard motors, outboard motors can be easily removed for storage or repairs.
Bolinder’s two-cylinder Trim outboard engine.
A Mercury Marine 50 hp outboard engine, circa 1980s
1979 Evinrude 70 hp outboard, cowling and air silencer removed, exposing its shift/throttle/spark advance linkages, flywheel, and three carburetors
In order to eliminate the chances of hitting bottom with an outboard motor, the motor can be tilted up to an elevated position either electronically or manually. This helps when traveling through shallow waters where there may be debris that could potentially damage the motor as well as the propeller. If the electric motor required to move the pistons which raise or lower the engine is malfunctioning, every outboard motor is equipped with a manual piston release which will allow the operator to drop the motor down to its lowest setting
What is an Outboard Motor
If you’re ready to join the fun on the water, and you’re new to the outboard engine on the boat, you’re in the right place. In this article, we will talk about basic information about the outboard motor, the pros and cons of the outboard motor powered by fuel and electricity, the main types of the outboard motor, the components of the outboard motor, and how the outboard motor works.
Different from an inboard engine that is usually mounted inside the boat and invisible or a sterndrive that is a combination of inboard and outboard engines, an outboard motor refers to the propulsion system fully installed on the outside of the hull, usually mounted to the exterior of the transom to power the boat.
In addition to offering propulsion, an outboard engine that sits on the boat also offers steering control as it’s built to pivot over its mountings and adjust the thrust’s direction. Often, the outboard motor is the first choice for fishing, recreation, and light commercial inshore boats. These engines provide ease of use alongside reliability.
Different outboard engine brands require different transom dimensions and sizes, that affects performance and trim.
| Outboard Brand – Model | Transom Angle | Max Transom Thickness | Transom To Bulkhead |
|---|---|---|---|
| Yamaha – F350 | 12° | 712 mm | |
| Yamaha – F300 | 12° | 712 mm | |
| EVINRUDE – DE 300 | 14° | 68.58 mm | |
| EVINRUDE – G2 300 HP | 14° | ||
| SUZUKI – DF 300 AP | 14° | 81 mm | |
| MERCURY – 300 HP | 14° | ||
| LEHR – 5.0HP | 14° | ||
| LEHR – 2.5HP | 14° |
