Stern mounting plates

[Mfoley312]

I've been through 3 or 4 adjustments, 5 holes in the hull, and a little bit of frustration getting my new transducer mounted correctly. I've finally got the correct placement of where I want the transducer, but the holes are stripped and the screws aren't tight after the last adjustment. I tried the toothpick trick and slapping a crap ton of 5200 on the mounting bracket but after the last outing, it started getting loose (worked great at first though).

So I think my next course of action is to get a transom mounting plate to hide the holes and provide a clean install, but I'm stuck and I want this to be the last thing I do.
I've found two on amazon, one is 1.5 inches thick and other (and most of the rest on amazon) are 3/4 inch thick. I think I'm leaning towards the thicker one and that way I can get longer screws in the plate for a more secure fit, but maybe it's too thick? Looking for advice from others who have gone through this so that I can finally finish this job correctly.

Thank you!

 

[Scott Danforth]

got a pic?

I would drill the holes a bit larger and fill with reinforced epoxy and while the epoxy is wet, wax your screws and install them

 

[gm280]

Always, when you are working with "stripped" holes, drill them out larger then they presently are, and fill them like Scott above suggested. They will be tight after that. As far as covering up the existing holes. Please don't do that unless you refill them and fair them off. Otherwise, they will allow water in and ROT. And ROT is the worst thing you want with a boat. JMHO

 

[Mfoley312]

https://www.dropbox.com/s/7bsgzkmzwx1vpzw/IMG_20190411_172244.jpg?dl=0

This is a pic from when the transducer was mounted too high. For the epoxy filling, any recommendations with brand or application? Never used epoxy before. Also, I assume that will be water proof and I don't need to use 5200?

 

[Alumarine]

3/4" - 1" is just fine for the mounting plate.
I cut down white synthetic bread boards I buy for around $4.

 

[Mfoley312]

3/4" - 1" is just fine for the mounting plate.
I cut down white synthetic bread boards I buy for around $4.

and then you just use short screws I suppose? Had any issues with brackets becoming loose when using short screws?

 

[JASinIL2006]

I used the cutting board material, too, but I was a bit more paranoid about water intrusion, so I got carried away...

I used two layers of cutting board. The first was attached to the boat with countersunk screws, with the screw holes into the hull and the entire back of the cutting board treated with 3M5200.

The second layer was attached to the first layer with screws that were long enough only to penetrate the first layer. That gave me a nice thick layer for transducer screws, with pretty much zero chance of water intrusion.

Overkill, I know. But it worked, and even came off fairly easily when I restored my boat several years later.

When I reinstalled the transducer after my restoration, I skipped the mounting board and just attached the 'ducer to the hull, making sure the holes were well filled with 5200.

 

[Alumarine]

and then you just use short screws I suppose? Had any issues with brackets becoming loose when using short screws?

Brackets have never budged.
Short as in 1".