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By Bob Trygg – Duluth, Minnesota - USA

Power A Seaclipper 16 Trimaran

Propulsion for small boats can consist of paddles, oars, or at times some type of motor, either electric or gasoline powered. In my case these options were going to need some reworking because the boat I was building was a Seaclipper 16 trimaran.

This type of design would not lend to the using of either paddles or oars because of the extreme beam. There was also a complication in the fact that this design is sailed and controlled from a fixed seat location with one's feet used for steering. This fact did not allow a single person to both start and control a gas motor easily from this fixed location. This and the need to have gasoline aboard suggested to me that the beginning point would lie with the use of some type electric motor.

It also occurred to me that the use of a trolling motor would be the best as they are readily available and are not very expensive. (I was able to purchase a new brand named motor for a little over $100 dollars at WalMart.) The next problem was how could it be configured so that it could be raised and lowered from the fixed seat location, not wanting to drag it in the water while sailing. There was also the question of what kind of battery would be needed to give me decent range and yet not be so heavy and large as to cause problems in fitting it into the boat.

Having had some experience with trolling motors in the past, I knew that one of the small motors with about 30 lbs. of thrust would serve to move the boat quite easily. They are surprisingly very powerful and I have had them move a 500 lb. boat at about 3-4 miles per hour. I also did some testing to determine what type of battery I would need by setting up the motor in a fixed tank and running it at full speed while attached to a standard group 24 deep cycle battery. This test showed that the motor could be run at full speed for about 2 hrs. More than enough for my use.

Because I wanted to raise and lower the motor like a lee board from the cockpit seat the next step would require some serious modifications.

The first of which was the tearing apart of a brand new motor to begin the modifications. I began the modification by removing the control head, which consisted of the speed control and the tiller assembly. Next the complete clamping and tilting mechanism was removed. All of these parts were discarded except for the speed control switch assembly. The next step involved shortening the motor shaft to allow only enough length to let the motor be deep enough in the water when tilted down. This step has to be done carefully as the shaft, which is made of a composite material, has to be sawn off without damaging the internal wiring. In my case I found a piece of metal tubing that was small enough to be inserted into the shaft tube and yet had an inside diameter to allow it to slip over the wires (4) that I had to protect. The next steps are better illustrated by pages 1, 2, and 3 of drawings showing the parts and assembly of those parts.

The following pictures show the motor attached to the boat, both inside and outside.

To complete the installation, I found that I could place the group 24 battery under the rear seat.

The addition of an off-on switch is recommended and is shown in following picture.

This switch is important as you would not want to accidentally turn on the motor when it is in the parked or raised position. The motor should also have both a pull up and a pull down line so that the motor can be held in place when going both in forward and reverse. These can be seen in the pictures and these lines are locked in place by clamcleats.

The final item to complete everything is the installation of the speed control. The saved control switch was fastened to a block, fitted with a control knob and mounted in the cockpit area near the pull up and pull down line clamcleats. This particular control switch gives us 3 reverse speeds and 5 forward speeds thus giving us complete control from the seated cockpit position. What luxury!

I believe that this motor arrangement could be used on boats other than the Seaclipper trimaran and could serve as an attractive means of auxiliary propulsion for many small sailboats.

The motor we used was a Minn Kota Endura unit which has the wiring color coded and the speed control switch has these color codings marked on the switch to aid in the proper assembly after it was stripped down for modification and installation.

Follow up and further testing will have to wait a while as the next picture illustrates better than anything that our area is not currently the best for boating. Think spring!!

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