mounting a trolling motor using docking cleat holes

[seville newbie]

Hello, i have been referencing your sight almost dailysince i acquired my '88 sea ray seville16' (i think you refer to it as a runabout).....anyway, tons of excellent info from many knowledgable folks and i would like a little input if i could? I purchased a minnkota endura 55 transom mount as a trolling motor but now i think i would like to attach it to the bow. I have made a bracket to attach the motor to and reversed the motor head already, my question is this....is there enough strength in the bow to mount the motor in the four existing holes from the docking cleat? I sure would hate to tear a hole in my new to me boat! Thanks for any input on this matter

 

[Silvertip]

Re: mounting a trolling motor using docking cleat holes

Without a picture of the cleat area or the bracket I can only guess but I'd say those holes are too close together to handle the torque loading the motor put on that area. Remember, the force is being applied at the end of a very long lever. Long levers multiply torque and the fulcrum is at the mount. You need to spread that load out a bit more. Look at the bow mount quick release plates and you will understand why they are as long as they are. Think this through carefully to avoid ripping a hole in your boat and possibly losing the motor.

 

[seville newbie]

Re: mounting a trolling motor using docking cleat holes

Here are a fewcpics of my setup

 

[Silvertip]

Re: mounting a trolling motor using docking cleat holes

Are those four cleat mounting screws actually bolts or just screws? if they are just screws you need to through-bolt them. The bracket itself looks fine but some backing is necessary behind the cleat and while I understand not wanting to punch another hole in a perfectly good boat, one more bolt at the forward end of the bracket would certainly help. But -- try what you have and pay very close attention for any movement of the bracket that would indicate you need more support. Flexing of the glass will crack the gelcoat.

 

[Kaplooi]

Re: mounting a trolling motor using docking cleat holes

I just made a custom bow mount for a transom mounted motor as well and I can tell you a few things I've learned. First, you should try to get it as far forward as possible so you can be as close to the centerline as possible or else it'll track sideways and you'll lose too much thrust making it go straight. In other words don't mount too far off to one side just because you have an existing mount point you want to use. Regardless you will have to get past having to drill several holes in your deck. As Silvertip mentioned, a trolling motor is effectively a big pipe wrench where you'll have 55lbs of torque applied at the end of a 3-4ft pipe which multiplies to a ton of twisting force at your mount point. Another thing I can tell you is that your mount being sideways to the direction the motor be pulling will cause the motor to twist upwards at the leading edge. You can tighten the mount lugs all you want and it'll still start pulling up at the front at high speed (Mine did this and it was offset to the side even more than yours appears to be). You'll need to either modify your bracket to be perpendicular to the direction of thrust (as it would be on a transom) or modify it to catch one of the plastic lips on the side of the mount to keep it from twisting off your mount. From what I've seen of my 50 lb thrust 42" shaft you can expect the motor to rip your mount off if you have only those 4 screws mounted at the rear holding the plate on. I'm using 8 screws mounted to a flat deck that's widely distributed and it still flexes a little bit at full throttle. Think of it this way. Would you expect your dock cleat to withstand 55lbs of twist at the end of a 3 ft pipe wrench for minutes/hours on end? Probably not.

 

[fishrdan]

Re: mounting a trolling motor using docking cleat holes

The bracket mounting looks kind of weak to me. I agree with ST on putting a bolt through the bow end of the bracket if leaving it as-is. Though, I would have centered the cleat on the bracket and then used 1/4" SS bolts to mount it (maybe even 5/16 or 3/8" bolts because of the small bolt pattern). This would be dependant on if the bracket sits flush with the hull when the rubber pad is gone. Actually, you want the bracket sitting flush agaist the hull, so it transfers the load to the hull and does not create a localized load where it's bolted down. I would also use a backer plate inside the boat, to spread the load. You want that mount as secure as possible. The motor hanging off of it will create huge stresses, more so when bouncing over waves than when the TM is in use.

Also, you want something crushable for TM mounting area or the TM could easily slip off. Face each side with some plywood. I would also extend the area the TM mounts downward, so it has more contact area. How do the TM screw clamps sit, flush or angled off if the welded seam? They need to sit flush. For the screw clamp ends, I would countersink the plywood with a Forstner bit, give it a cup to sit in.

Basically, you want to be able to; #1 grab on the bracket, #2 shake it like a gorilla, #3 have no movement between the bracket and boat hull.

 

[seville newbie]

Re: mounting a trolling motor using docking cleat holes

Thanks guys....the bolt holes are probably 2 1/2" apart now with the factory aluminum backing plate behind the through bolts...I do not want to drill more holes as of yet because if this motor works better in the front I will upgrade to the minn kota with autopilot and remote steer. Basically I just wanted to rig it up as a test run for manuverability for future reference...thanks again for all the advice