Repair holes in transom from old depth sounder

[frankthomas]

I am replacing the depth sounder on my fiberglass 18 footer. I doubt the new bracket will use the same holes as the old one. I've not done the job yet because I don't want to get half way through and not finish it. Assuming the mounting screw holes from the old bracket do not go all the way through the transom what should I use to seal them? And if they do happen to go all the way through the transom what is the method then? Thanks!

 

[MTboatguy]

3M 5200 is what I have used over the years, once it sets up it is very durable and water proof, couple of dabs will do you, they make it is various colors so you might be able to get a close match to the boat, I just pull the old screws sand any burr flat squirt in the hole then smooth with a body paddle let dry.

I have also seen people do the same thing, then once they have the 5200 in the hole, install a stainless screw and tighten down, plugs the hole and not really noticeable.

 

[dingbat]

Your integrity of the transom is is at risk.

An "sealer" will harden and shrink over time allowing water to penetrate the core of the transom. Nothing short of a permanent solution will suffice.

Get a stainless steel flat head screw of the same size that held the existing transducer in place. Counter sink the hole large enough for the flat head to sit an 1/8" or so below the surface of the gel coat. Fill hole with 30 minute epoxy, smear some on the threads of the screw and drive the screw home.

Then fill the countersink with Marinetex or similar material. Overfill the hole a bit to accommodate any shrinkage as the material dries. Let dry and sand smooth. A bit of rubbing compound with remove the remaining scratches.

Can't tell the holes was ever there and no chance of moisture getting to the core.

 

[Bt Doctur]

Any place you drill a hole put the transom at risk.
You can:

drill the hole, fill it with resin, let cure, redrill, install screw with sealant
Drill a slightly over sized hole, insert hardwood dowel with resin, drill correct hole, fill with resin, let cure, drill correct size hole , install screw with sealant

 

[Old Ironmaker]

All my transducers are mounted on that white plastic board they make cutting boards with. 2 part epoxy welds them to the aluminum and then the screws never touch the transom proper. 1 has been on since 1994.

 

[5150abf]

JB weld and a screw in any hole left open, not as elaborate as BT Doctur, which is the correct way to do it by the way, but still a viable solution in my opinion.

 

[KnotConnected]

Why the filling with resin just to drill it back out?