When we are going into and out of tight places like marinas, the wind can move the bow (front) of the boat in ways that are dangerous - and can result in collisions with other boats or docks.

A device known as a bow thruster can mitigate this problem by adding a motor and propeller in the front that can be operated by the helmsperson.

We had one installed in 2014, an external model, but it proved inadequate for our 52,000 pound boat with a high freeboard (wind side area).

So we decided to haul her out once again an install a proper internal thruster, this time a 10 horsepower Vetus model BOW16024D, that runs on 24 volts and has 350 pounds of thrust.



In the above photo, I have laid out some boundaries. The Vetus thruster requires only 1/2 of the tunnel diameter below the waterline. The upper tape defines the waterline and the next one down is the 1/2, or 5" line since the tunnel is 10" in diameter.

The lower rows of tape are the lowest the tunnels can be in the hull. I chose 5" as the minimum distance between the bottom of the tube and the bottom of the hull.

My goal was to keep the thruster as far forward as possible for two reasons. The first, the minimize the impact on cabinetry in the V berth and second, the provide a longer moment arm for the thruster to operate with and create more turning force.

Below the tape area is an area with the blue bottom paint removed. This is the area where the old external thruster was attached. I had to repair the old 2" hole and 2 bolt holes in the hull.



In the photo above, you can see I've decided on a center for the tunnel and inserted a 1/2" steel rod through a hole in each side. This is a guide rod for the router appliance that I used to cut the holes for the tunnel.

You can see the old external thruster laying on the ground near the yellow drill. Way too small for Abundance. It did work in very light wind, but it slowed the boat about 1/2 of a knot.



Here I am suited up for cutting the holes. Bill Drewes, a coworker at Farmer Mold and Machine Works, created and made the router appliance that keeps a constant radius on the cutting bit while the router is rotated around the guide rod.



After the holes were cut, I inserted the tube for a fit check. No more than a 1/8" gap occurred around the periphery of each hole. Well done, Bill! Thank you for making the great router appliance.



You can see the close fit in the inside where sunlight illuminated the tube.



This is a view of the glassed-in tube in the V berth. I used West Systems epoxy and bi-axial glass. Don't ever used chopped strand matte with epoxy. It won't dissolve the binder and the matte will not lay down. I applied 2 layers of matte then 4 layers of bi-axial with increasing length of strips.

This was after we packed thickened epoxy into the joints all around the tube.



I glassed the outside edge and faired it. I also added "eyebrows" ahead of the tube, with a 1" gradual rise to decrease the amount of water that crashed into the aft portion of the tube when underway. I also radiused the joint where the tube and hull meet.

Yvonne is applying the barrier coat, Interlux Interprotect 2000 before applying the anti-fouling layers.



This is what the motor looks like in the V berth.



This is the appearance after bottom paint was applied. I put the propeller on later. It tested okay the first time and has a lot of thrust!