Technical Bulletins

Marine Engine/Drive Variations

The AERA Technical Committee offers the following information regarding marine engine/drive variations.

Sterndrive:
There are two basic types of sterndrive arrangements.
"A" The engine is mounted inside the boat. The transmission/drive unit is
outside, attached to the transom. Power is transmitted via a coupler and
universal joint.

"B" The engine and transmission are mounted inside the boat.  The drive
unit is outside, attached to the transom. Power is  transmitted via a
typical clutch and pressure plate assembly, which is electrically
actuated. Clutch actuation occurs automatically when shifting, and
requires no attention from the operator of the boat.

Inboard:
The engine and reverse gear (transmission) are mounted inside the boat. A propeller shaft is connected to the reverse gear (transmission) and is run out of the hull through a shaft log with packing gland. With this type of drive, the engine can be installed with the flywheel facing forward or aft.

V-Drive
This is a modified inboard installation. The engine is mounted with the flywheel forward. The V-drive is mounted to the flywheel end of the engine facing forward. A propeller shaft is connected to the rearward facing end of the V-drive and is run out of the hull through a shaft log with packing gland. 

Jet Drive
The engine is mounted inside the boat with the flywheel end aft. A high speed pump is connected to the engine. The pump draws in water through an intake grate, increases its velocity and forces it out through a directionally adjustable nozzle, which is mounted outside the boat.

The AERA Technical Committee