TOPIC: transom penetrations

I epoxied the pieces of the Glastron transom together yesterday. Looking at it I realized that I have 3 known penetrations in it: two 1" holes for the motor well drains and one 1" hole for the drain at the base. My thought was place the new piece in place and mark with a pencil where the holes are located. Take the piece out and drill 1-1/2" holes where the penetrations are to be located. Fill these holes with epoxy, put the piece back in and mark where the holes are to be on the epoxy. Take the piece out again and then drill the 1" holes for the drains. After that, do the permanent installation of the new wood in the boat. Would this actually work or is there a big chance of having alignment problems? Other thoughts?

I think you're spot on. If you're worried about alignment you could start with a 2" hole provided that you still have plenty of wood surrounding the hole. Probably shouldn't get too close to the edge. Good luck.

If you can do it, you have to be pretty precise. When I put my new drain tube in I put a good quality gutter sealer on the tube. It will outlast me. I put in plastic 1/2 inch tube where it had been steel. What a mess that was. I put the original drain in and you can't tell it's plastic just by looking at it. I cut if flush with the transom on the inside. I used a gutter seal because many years ago when I did the repair on my MFG I seal around it with gutter seal and it is still there doing it's job after about 15 years. It is 1 inch cooper tubeing. Thick wall.

The absolute best way to seal a penetration through wood is drilling it oversized, filling it with epoxy, then drilling it out to fit the fastener. We used this method any time we were dealing with a penetration through cored materials, especially balsa. If it's done right, there is ZERO chance of water intrusion-



This shows it with existing fiberglass on the outside, which can be left intact if you have inside access. Drill it out a good 1/2" or more larger than the hole to be drilled ( B ), fill it with thickened epoxy (C), then drill the hole (D). Goop up the through bolt with some sealant just to keep water out.

Of course, if you just drill it and use PLENTY of sealant, and do it right, it'll last, too... But, the above method works!

-Andrew

I've done this often on my sailboats, it is the best way. The only thing I would add is to add chopped glass to the epoxy to make it a little stronger and resist cracking.

Oh, and use the same resin you'll glass the transom together and in. If that is epoxy, use epoxy to fill the hole. If you're using polyester, use it for both.

Sounds like either chopped glass or some kind of thickener should be added to the epoxy. That is easy. What I want to do is to re-use the existing drain holes in the transom and deck fiberglass. I figure I can lock in the plywood position by putting 2 screws through the existing fiberglass to lock it in place and also make it possible to reproduce the position. (2 more screw holes in this transom is not going to be a big deal, considering the Swiss Cheese that it is right now.)The alignment on the bottom hole I am not worried about, it is the top motor well holes. They are going to need to line up with the holes in the deck, which has been removed. I am assuming that the holes were drilled perpendicular to the plywood, but given all the construction faux pas' that I have found in this thing so far, it makes me wonder. Anybody tried this before?

I think this whole thing will be easier by drilling and filling the holes while it is in the horizontal position before the wood is permanently installed. I just want to be sure I am not overlooking something that could be a problem.

Andy, how did you cut the keyway in the center of the plywood?

Robert, the drains on this boat were the 1" brass sleeves and I intent to replace them with the same. It should be a little easier than the drain you were working with.

Dremel makes a saw blade that looks like this-



which works well in larger holes- Just be careful since you have to use it without the guard...

In smaller holes, you can take a finish nail and bend the tip over 90 degrees, to make a kind of
"L" shape, chuck that in a drill, and use it. It doesn't have to be pretty.

I like to inject my filler with a pastry bag, or by putting it in a ziplock and cutting off the corner so I can squeeze it in place. Then, I tape a piece of plastic over the repair to hold it all in place until it cures, one of those plastic body filler squeegees works well for that. If you do it right, the repair ends up nice and smooth inside, and won't even need sanding

-Andrew

Well the big thing with mine was the transom was solid. They had a chunk of either black 1/2 inch pipe or galvanized through the transom.After cleaning it up the wood was solid and dry. That made things easier. I just replaced it with a plastic nipple cut off at the proper length. My other transom has no plywood core or any core as far as that goes.

"Sounds like either chopped glass or some kind of thickener should be added to the epoxy."

Thickener will help it stay in place while it cures, chopped glass will give it more strength after it's cured. Probably both is best.

now this is a great idea, thanks for thing of it and passing it on to the rest of us. frog