How Do Boat Motors Work?

Boats run on either outboard or inboard engines, and many even use both. Inboard and outboard boat engines work in similar ways to car engines, but utilize the water they float on too. Both engines run on gasoline or a mixture of gas and oil for the two-stroke engines.

Inboard boat motors run when gasoline combusts in the firing chamber and pushes the piston down. Each piston’s movement causes the crank to spin and push the other pistons back to the top of the chamber. The power the engine creates is transferred to the propeller by way of a drive shaft. As the engine’s RPMs increase, the propeller will spin faster. RPM stands for revolutions per minute in reference to the number of times the crank is spinning per minute. The inboard engine uses the water the boat is floating on to cool the engine instead of a radiator.

Outboard boat motors are either two-stroke or four-stroke engines that run in the exact same way the inboard motors do. The main difference between the two engines is placement and configuration. The inboard engine is located in the boat’s hull and has a propeller shaft that protrudes from the bottom of the boat. The outboard engine is positioned at the rear of the boat and larger boats can support more than one outboard motor. The outboard motor has an attached propeller that sits in the water while the engine up top stays out of the water. The surrounding water also cools the outboard boat engine same as the inboard motor.