Install a Stern Drive Unit

red boat on the water
  • 6-12 hours
  • Intermediate
  • 1,500-3,000
What You'll Need
Marine grease
Socket set
Stern drive

A stern drive unit is a type of marine propulsion which can be fitted to most boats. This is a type of inboard motor that benefits from many of the advantages of an outboard engine. The engine itself is mounted on the boat and power is delivered through the shaft which passes out of the boat to the out drive. The propeller itself is outside the hull and this looks the same as a normal outboard motor. The bottom system is the bit which contains all of the gears and the propeller.

Steering is done by turning the stern drive unit around which means that no rudder is required to maneuvered. Installing a stern drive unit is actually quite easy, it involves making mechanical, electrical and hydraulic connections to other components on your boat.

Step 1 - Choosing a Stern Drive Unit

Choose a stern drive unit which you will be happy with. There are many different examples of stern drive units from a wide range of different manufacturers. These are all about the same but you will need to choose one which is compatible with your engine and suitable for your requirements. If you are confused about the different types available then be sure to ask for assistance from a professional boat engineer.

Step 2 - Mounting the Transom Shield

The drive shaft will pass through the bottom of the boat and through the transom, to make this possible the transom shield needs to be fitted to the transom. Prepare the transom shield before attempting to fit the stern drive unit to the boat. Position and fit the transom shield according to the manufacturers instructions.

The electrical panel needs to be fitted inside the transom shield as it's this which provides protection for the electrical circuits used.

Step 3 - Hydraulics

The transom shield needs to be connected up to the hydraulic lines in your boat. Loosen the bracket of the pump before fitting the hydraulic lines to prevent them from getting crushed or damaged. Whenever passing anything through the boat make sure that you use washers on both sides of the holes. Polished washers need to be used on the external face of the stern to prevent the bolts from corroding.

Step 4 - Exhaust

Mount the exhaust horn onto the boat, most models will have a back flow valve to protect the engine, if not then consider fitting an aftermarket valve.

Step 5 - Propeller

Fit the propeller to the stern drive unit and make sure that everything is tightened up properly. Check the water tightness of each hole passing out of your boat to make sure that no damage will be caused by using this stern drive unit.

Now all you need to do is test your boat and check that everything is working as it should be. You should be able to benefit from enhanced maneuverability without having an ugly outboard motor on the back of your boat.