help on mounting something without drilling gunwale

I cut a large sheet of plywood to go on the bow, to mount my trolling motor to, and underneath I'm gonna put elastic cargo net to hold life jackets.









On the port side I ran 2 4-gauge wires to feed my trolling motor from the battery in the back, and on the starboard (OMG I feel so nautical!) I have the wires ran for the front marker and headlight. So....I can't really just drill through there.

There has to be some sort of thing I can put on the bottom of a bolt that'll grip the bottom of the gunwale and hold everything tight. But I walked around Menards the other day and couldn't find anything that would work.

Any ideas?

Would a bolt thru the plywood cover with a flange or piece of metal on the underside of the wood positioned to grip the underside of the gunnel and tighten the bolts down snug work ??

TNtroller said:

Would a bolt thru the plywood cover with a flange or piece of metal on the underside of the wood positioned to grip the underside of the gunnel and tighten the bolts down snug work ??

Click to expand...

Thats what I'm thinking, but I can't find anything that would work as a flange.

Any ideas?

There may be a couple of ways to do that. Can you post a better pic. of the underneath of the gunnel so we can see what you have to work with. If the gunnel protrudes into the boat, and has a flat surface under it, it could probably be done with two pieces of aluminum angle that are bolted or welded together that would look like a straight up and down Z. The top would bolt against the plywood with carriage bolts, and the bottom would go under the gunnel. You may have to cut a leg down on the angle to get a snug fit.

You could fasten a length of wood or aluminum angle against the hull, just under the rounded gunnel, by putting holes through the sides of the hull. Then use long bolts down from above to tie the 2 together.

Are you saying you ran your wires inside the gunwale?

I hate to say it, but I think with the forces from a trolling motor plus the tendency of everything on a boat to vibrate and shift around, there really isn't any option I would trust short of very securely bolting the plywood thru the gunwale.

Can you pull your wires back out and pull a string with them to use to re-pull once you are bolted up?

Maybe a picture will show my concept better ... but of course you need to size/position everything so that the bolts through the top grab into the piece placed along and below the rounded gunnel edge.

2 thoughts occurred to me since what I said last night.

One similar to what Dale is showing you except I was thinking of going all the way across the sheet of plywood, transverse to the keel-line of your boat with 2 or 3 pieces of uni-strut, kindorf, or u-channel. Cut the ends down so it fits under the gunwale and bolt thru just out from gunwale edge just like Dale shows. This would also stiffen up the plywood if you intend to operate the trolling motor with you sitting on top of the plywood. Downside to this option is the expense.

Other possibility would be truck cap clamps. I made rod holder mounts out of some old cap clamps I had laying around by drilling and tapping the top section of the clamp. If you used only the top section (1/2 I have the rod holder mounted to) you may be able to cut off the down leg so it just comes up against the plywood when thru bolted. Not sure how much I'd trust this long term though.

Thanks everyone for your help!

I think I'm going to take duckfish's advice and pull the wires back through and use a piece of string to repull them once I'm done running the bolts.

I don't think anything else will safely take the forces from a 55lb thrust trolling motor getting beaten through the water.

I like Dale's idea - -
a 1x2 firing strip to hold the deck from sliding around and then
some aluminum flat bar of your choice bolted thru the deck and wood strip.
then, if you still really don't want to drill holes, use 1" velcro tape to hold it all together.

Once you put those bolts thru the gunnel, you may not be able to get the wires back thru as they currently are. Just sayin'???

The only other option I could think of? Get some sturdy angle aluminum and rivet it to the hull just below the gunwale, then make a spacer from either plywood or something else to pull flush with the top of the gunwale. Use that to bolt the plywood to it. That would likely be the single most sturdy design, better than bolting to the gunwale even, I'd think. Plus, rather than transferring the stress from the motor to just the gunwale, you're transferring it to the entire hull.

I know you've said you have your solution but I'd try something like this. Take a few (4-6) galvanized stamped steel gate handles like used on wood fences. Cut one end short enough to fit under the lip of the gunnel. Drill a hole through the deck and the handle near the end that fits under the lip. Use a carriage bolt (rounded head up so no trip hazzard) to go through the deck and the handle and a nut under the handle. Jut tighten the nut until the desired amount of pressure is acquired to hold the deck in place. If for some reason this doesn't hold the deck from moving, drill a hole on each side that goes through the deck and the lip and put some sort of pin in it to keep the deck from sliding.

Sorry but I rushed the sketch, but I'm headed out the door to see if the crappie are biting.

I love these gunnel clamps, bought 4 of them and use them for all kinds of different ideas, without drilling.

https://www.marinegeneral.com/productdetails.asp?productid=1506481&directoryid=

Very sturdy.