How to Install a Bow Thruster

What You'll Need
Bow Thruster
Dry Dock

A bow thruster is also known as a tunnel thruster. These bow thrusters help a boat turn in very tight spaces without the need for tug boats. With a thruster, you do not need to worry about spending money on these services. Without a bow thruster, you would have to turn the boat using the main propulsion system, which will involve traveling forward. A bow thruster means that you can stop, stand still and turn around on the spot. Fitting a bow thruster is very easy as long as you prepare and take your time to complete the project.

Step 1 – Locating the Tunnel

To use a bow thruster, you will first need to cut a tunnel into your stern. To do this, you need to choose a location for the bow thruster. Ideally the bow thruster propeller will need to be located as close to the front of the boat as possible and as low as possible. A minimum of 6 inches need to be between the stern bow thruster and the top of the water. If you’re working with a fiber glass hull, then you may need to use stiffeners to make the tunnel stronger and less susceptible to damage.

Step 2 – Cutting the Hole

Once you have chosen your location, you then need to drill a pilot hole on the center line of the tunnel. Check that there will be plenty of clearance between the tunnel and the water. Place the rod through the hole and level. This will allow you to find out where to drill from the other side. Cut out the rest of the hole and keep a 1/8th inch margin, while trying to keep everything lined up properly.

Step 3 – Clamping

Secure the shape of the tunnel using clamps, make sure that the tunnel is level and make an epoxy paste. Apply the epoxy around the radius of the hole. If you are working with a metal hull, then you will need to weld the tunnel in instead of using epoxy.

Allow the epoxy to dry overnight and then sand it down so that it’s flush with the body of the boat. Anti-fouling paint should be painted onto all of the components. You should also be sure to paint inside of the tunnel to prevent salt water from causing harm to the bow thruster.

Step 4 - Installing the Bow Thruster

The bow thruster is separated and positioned over the hole. The screws can then be tightened to hold the bow thruster in place. Then all that's left to do is connect the bow thruster up and test it out to make sure it's working properly. Put the boat back into the water and check that you can use the bow thruster to turn the boat around.