As usual, if it can be done, I want to build it. I found the idea of making a powered kayak an irresistible urge. Sure, they make one for $499 that does the exact same thing, but I already had a trolling motor from an old boat sale. Why buy it when you can make it and I am too cheap to pay that when I know I can make it. :)
So to start out, what you are looking at is a Minn Kota Endure 40 (40 pounds of thrust) mounted on to a Ocean Kayak Prowler 15. It runs at a top speed of 4.6mph on 5 and 3.6mph on 4 and various on down and speed 2 is about 2mph and perfect for trolling. Even though 5 sounds like the speed you always want to use. 5 draws about 30amps and 4 draws about 16 amps. So for an extra .9mph you draw almost twice the battery life. So you can clearly see with a bit of patience and cruising at a lower speed you can make the battery last a lot longer.
This is the mount that I made for mounting the motor on the stern. I had some 2 x 3 channel laying in the shop and cut it out to make the mount. The the actual mount is just a long piece of channel. The riser is a smaller section and cut on a 45 degree angle to mount to the rudder screws. This worked, but it was clear that turning the motor on and off would torque the motor forward and backwards and apply excessive strain to the molded in screw mounts for the rudder mount. So I added another piece of channel cut long and thin to go over the rudder storage channel. I left part of the 3″ side whole to bend open and serve as ears to bolt the mount to really stiffen the mount. Then weld it all together, prime and paint it all.
The next part here shows the attachment of the mount. The red disks are polyethylene from and old RAM canoe that died in a previous life, but it serves great for backing plates for kayak mounts. Stainless Steel fender washers and nylon locking nuts complete the mounting hardware.
You can see here the bent out ears made from the 2×3 channel and how they are bolted on with a rubber washer between the ears and the kayak and the bolt and the mount. This stiffens the mount very well and protects the kayak.
Next is the access hatch that I needed installed so I could get access to install the nuts for the mount and wiring for the plug for the motor connections. I bought this access panel from Austin Kayak along with the front hatch you will see later. This was very cheap and cost about $3.50. I am pretty sure I spent almost as much on the SS screws to mount it as I did on the hatch itself. I added RTV glue to the access hatch before screwing it on and closing it up.
Now, we get to start on the motor and modifications to it. The top of the motor with the controls all needed to be removed. I saved the variable speed control switch and aluminum bar and connection for later on. The shaft was too long and need to be cut down about a foot. I did this with a hacksaw blade, but slowly and by hand so as not to cut the wires.
The 3/4″ PVC elbow I was trying to fit on to the shaft would not slide on. My solution was to gently sand the top with a ledge smaller so it would slide on. I did this on my belt sander and it made real quick work of it. Then it slide on very easily. I used RTV glue to make the seal and threaded a 1/2″ long 10-24 bolt through the elbow into the shaft. The RTV glues to the elbow, but does not like grabbing the fiberglass or composite shaft. Tapping a bolt thread through the PVC elbow and into the shaft locks it into place.
This is the Ranger trolling motor two piece plug and it can be purchased at Cabelas, Ebay or Amazon. Most other plugs will not handle the 10awg wire or are just not big enough and will probably fail due to the heavy current draw. This is a heavy duty plug and I put the tape measure in the picture so you can see really how big it is.
There are cheaper plugs out there, but you will be running 30amps through this and how high the inrush on starting the motor is, I don’t know, but its a lot higher! Spend the money and buy this plug!! There are not any other plugs this heavy and with 4 wires.
I got the great idea to use a fuse on the first run. I got a 30amp inline waterproof fuse from AutoZone and wired it in. On the first heavy test run I ran the motor on 5 a lot. One time I had the motor off and ran it right to 5 starting out. The inrush of current plus the load of a still kayak on the motor provided enough draw to not only blow the fuse. The fuse blew into pieces and deformed the plastic fuse holder enough to be unusable. You can send a lot of current through this, buy the correct plug!
I thought of moving up to a 50amp fuse, but then thought Minn Kota never had a fuse on the motor before. Maybe their engineering department know more than I did. :)
Now on to completing the wiring in the back. The PVC elbow is a slip to screw and that allowed me to use a 3/4 by 1/2 threaded reducer and screw a 1/2″ wet location gland over it. The wire was encased in heat shrink tubing and then the electrical plug was added. Each wire was fitted with a crimp connector to attach to the four terminals on the connecter. Make sure you fill each of the wire insert with dielectric grease before crimping it closed. This is very important as corrosion will build up in the connectors and some day in the future you will loose connection and have to remake the crimp connections.
The same for the plug in the kayak. Make the 4 crimp connection with grease and RTV it into place. Some water always gets into a kayak. its a moist environment. If you do not use the dialectic grease, your connection will fail, eventually.
Next was the center hatch. I did not have one and had to install it to have access to the center and I got that from Austin Kayak also. The first picture on the left shows the webbing as it some with the hatch. The right picture is the webbing cut out so I had a place to insert the control switch. This was just all carved out with a sharp pocket knife. Just shave a little hear and there. All done in a 1/2 hour while listening to music and it’s not as difficult as it looks.
For the switch to be mounted to the hatch I just drilled a hole right when I needed to mount the switch so it all lined up in the area I carved out. Then took the hacksaw blade and sawed a slot for the key on the switch. Then again a bunch of RTV glue all round in the open area and pressed and clamped the control switch in over night to setup and stay there.
The right picture is the back with the switch RTV glued into place. The left is the finished hatch cover ready to be installed.
The picture on the right shows the cable being connected to the switch. Notice the fuse, which I thought was a good idea, but blew leaving me stranded with only to paddle again. The left picture shows the knob slide on and ready for action.
Making the knob was pretty easy. I drilled into a pressure treated 2×4 with a 2 1/2″ hole saw until it started. Then removed the pilot bit and drilled the rest of the way through. Then ran a Fresnel bit in to make the opening for the aluminum rod. The bottom of the left picture is the exact parts that connect to the switch before taking it a part. I just cut it off and epoxied it into place. The top numbering was made in AutoCAD and I think there is a 28 degree turn per snap of the switch so I can see exactly what speed I am on. The knob just slides on and off and I just put it in the backpack on my seat when transporting the kayak. I just put several coats of varnish on the wood to protect it. The paper was seated on a light coat of varnish like glue, allowed to dry and covered in various more coats to seal it in.
The Battery ended up behind my seat as there was no room in the Prowler 15 up front with the battery up right. I should have bought the more expensive AGM battery which could have went on its side. I would recommend this if you start to make your own as it helps balance the load better. I used some of the extra plastic to make a cover for the hole for the battery wires. I could not get the nut for a gland connection to the spot. My arms just would not fit back there. I also cut the bottom of a battery box off to cover the battery and strap it down. You do not ever want to see a battery short out and it would melt holes into your paddle, net pole or what ever touches those terminals as well as destroy the battery.
That is about it. Size the links for your rudder cables and replace with chain or what ever you need to make it link up. This rope was just a temporary solution to make sure I got the length correct. Now get out on the water fishing!