Transom Repair Questions - 1045 Alumacraft Jon circa 1981

[rootbeer]

Hello. I recently acquired a 1045 alumacraft jon boat with some transom issues. The wood on the transom had significant rot, and I managed to remove it. Drilling out the rivets did not go smoothly, as I hope you can see in the pictures. I have read the posts on this site and others until my eyes have bugged out.

My first question is about the bolt holes that are now much bigger. Money is very tight, so no new transoms or $100 welding jobs. Should I use: JB Marine Weld, 3M 4200/5200?, or something else to return the holes to the original size, and how to go about this? My plan is to use 1/4" SS bolts with washers and locking nuts to attach the transom. I plan to put a rubber washer between the SS washers and the hull, and seal both sides with 3M 4200. On the worst hole, the washer combination is not quite big enough to cover the double hole completely. Transom wood will be exterior grade plywood sealed with spar urethane.

Should I ask each question in one thread or start a new thread for each question. I have some questions about rivets and painting.

 

[Ringo Steele]

For the bigger hole, you could use a stainless steel fender washer along with the 4200. They are about 1 1/2 inches diameter for the 1/4" hole size. If you use the sealant under it, you shouldn't need the rubber washer.

 

[rootbeer]

Should the nuts go on the outside or the inside of the boat? Does it matter?

 

[Ringo Steele]

From a fastening perspective, it probably doesn't matter. I put the nuts on the inside so the outer surface of the hull would look better. It may also be easier to get a good seal that way. I haven't seen a boat with the nuts on the outside, yet...

 

[TightyDub]

i just replaced my transom as well for the same reasons listed. there is no wrong way in my opinion,
to save money i about jb weld/ water weld (same thing just the waterweld you can actually use it to patch something out underwater) and 5200 marine adhesive sealant... i went with 1/2 inch galvanized and washers on both ends, i put the nuts on the inside, i had the some problem trying to drill out the rivets, i just drilled 1/2 inch bit size to make them bigger to fit a bigger bolt 1/2 inch isnt really necessary but i just re-drilled all my transom holes heavily laced the holes bolts with 5200 and the holes i didnt re-drill i just Jb welded them...i ran out of money my next step is to paint and i have been taking it fishing, JB weld holds up for me i wouldnt recommend it on a spot that could be scratched like the bottom of the boat or spot that could flex or bend it will crack it but for the transom i made ZERO supports and just re-did everything and it turned out great and does not leak a drop

 

[rootbeer]

Thanks for the replies. I feel better about at being able to fix the mess I made of the first holes I drilled.

Now I don't want to make the same mistakes on the holes I have to drill to remove the box seats in the back so that I can actually put new wood in. I have read multiple posts and tutorials on how to remove solid rivets and they all say use the right drill size for the rivet. There are nine rivets for each box seat, three in the side of the boat, three into the back bench, and three into the floor. The three in the seat are pop rivets, but the other six are solid.

How do I know how big the rivet is? Should I assume 3/16?