Transom-Hull Joint

[Jim Surdyke]

The rebuild of the transom on my 1936 ketch required the replacement of several white oak ribs as well as all of the 12/4 white oak blocking between the ribs at the top of the transom and the quarter logs that the hull planks are screwed to. I then replaced the orginal horizontal 1/2" layer of clear pine and the 1" thick layer of mahogany planking with three layers of CPES soaked 1/2" marine plywood cut in 8" strips, using SMITHS Tropical Hardwood Epoxy thickened with colloidal silica.

My next task is to seal the joint between the edge of the plywood transom and the ends of the 1 5/8" thick Long Leaf Yellow Pine planking.

The gap betweeb the transom and the planking varies in width from 3/16ths to 3/8ths of an inch.

My dilema is what method to use in sealing this joint. As the edges of the first layer of plywood were bedded in SMITHS Fill-it to form a seal, the joint is only 1" deep.

The job is to protect the edges of the next two layers from water penetration and have a sharp edge to finish for appearance.

The transom will not move, but the planks may. Should I use a soft caulking, or can I use a hard fairing? Or both?

[Dale Harvey]

If the seam is that bad, the only thing that MIGHT get you there is Smith's two part polysulphide caulk. Once it sets it will be possible to shape it with a random orbit sander. If you follow his directions, at least it will keep the seam sealed up. That 3/8 is a bit much to ask paint to stick to and 3/16 does not have enough material to stretch much.

[Bob Cleek]

Ah... yea... 3/8" is a bit much. Way too much. How did you end up with that much daylight there if you put on a new transom? Something isn't right. I wouldn't be too sure about any kind of goo solving that kind of problem.