Transom leak

Jut replaced transom on wood Grady White, along with couple of the lapstrakes. Still experiencing couple of very small leaks in bottom seam. Tried caulking with 3M 4200 but not successful. Will pull out this winter and really look at but anyone know of better caulk to seal the entire seam between transom and lapstrakes/garboard?

 

why not an epoxy fillet?



pls note I am in the epoxy business - but seems ideal for a fillet like that used on the hull, bottom seam of stitch and glue projects.

I'd be interested in reading what other folks suggest!

paul
progressive epoxy polymers inc

 

The only way is to open the seam up. I doubt you could fix it without removing a few screws. 4200 will work, or polysulphide even better. Should be bone dry.
I think epoxy would only create more issues. You've gone to the trouble of replacing the transom. Epoxy is not for you. Yes, the transom frame could have been coated with epoxy and that would extend its life in a traditional planked boat. But never should it be used in the seams. Too much movement to retain the bond.

 

Who knows what's causing the leak, it could be one or a combination of several things. Agreed on a traditional lapstrake build Alan is correct, way too much movement for an epoxy bond to work, though one of the more flexible formulations would. Polysulphide is my usual recommendation under the LWL for wood to wood joints. 3M-4200 is a polyurethane and it can take weeks to fully cure. If used in under the waterline applications it must remain under pressure during the cure, or it will release. The same is true of all polyurethane sealants.

Without pictures and likely some disassembly, it's difficult to speculate. As a rule, no goo in a tube is going to fix this. Lapstrakes builds require nice, tight fits and a solid support structure or they leak. Gooing up the laps still requires the support structure be solid. The usual "ills" are fastener condition, fasten hole condition and support structure weaknesses. This assumes good lap faying surfaces.