Installing transom xducer - help

[bottomline]

I'm upgrading the electroncics and adding a new 1KW transducer on the transom. I've installed many transducers, but this thing is HUGE and heavy compared to the 'normal' ones and comes with 5 3" long lag screws :shock:

My question is related to drilling the 5 long pilot holes. Is it ok to put screws that long into the base of the transom?

Any recommendations or things to look out for ?

Boat: 1992 Explorer 24 (246g)

Thanks
John

 

[Tim67580]

I would personally get some screws a little shorter, maybe 1 3/4 to 2in as the 3in will likely go all the way through the inner and outer layers of fiberglass. The most important thing is to make sure you seal the holes correctly to avoid water intrusion. If possible I would drill the pilot holes one size larger, inject with epoxy, and let it cure. Then redrill the holes the appropriate size.

You will also want to seal with 3M 4200/5200, or something similar. I have a 30 year old grady and it has a wet transom around the transducer mounting area due to improper installations over the year. Nothing I can do now but sit and wait.

 

[The_Chain]

I agree with what said above, you dont need screw that go all the way through. I will be adding a second transducer next week, the first one i did this spring and it was easy...make sure you seal it really good.

 

[bottomline]

I like the idea of oversizing the pilot holes and sealing with epoxy.

Thanks for the advise
John

 

[seasick]

I like the idea of oversizing the pilot holes and sealing with epoxy.

Thanks for the advise
John

I don't. Since the epoxy dries hard, it can crack as the screw is threaded in. You should drill the appropriate pilot hole, squeeze some 4200 or 5200 into the hole, then mount the bracket. Coat the screws threads with some 4200/5200 ( near the top is OK, you don't need to coat the whole screw) and put a little sealant under the screw head. Make sure that you have already determined where the mounting bracket needs to be. You want to avoid having to loosen the screws to adjust the bracket. If that is the case, apply new sealant (4200/5200) to the screws.

The hull is pretty thick but 3 inches sounds too long. I know that 1 1/4 are fine at the top of the transom and it is thicker near the bottom.
If you remove the drain plug and stick a wire or something in there until it just reaches the back of the transom, you will get an idea of how thick the material is.

 

[gw204]

You won't have any problems with the epoxy plug cracking as long as you drill your pilot holes properly. They have to be a little larger than when screwing into wood.