Re: Transom rot help please
I wouldn't change the angle of the transom, or the curvature, or anything – aside from altering the appearance of the boat (which may or may not matter to you), doing that will make so much more work than you think and will be more difficult than making a good repair to the existing structures.
It looks as if the stern knee (with the backstay tang incorporated) the starboard transom beam and the starboard fashion piece (the "frame") are in good order – and the starboard deck and planking. So it's the structures on the port side to deal with.
First I would clean off a greater area of planking to establish the extent of decay – and also check carefully inside as well. If it's not extensive, or not in many planks, then you should be able to scarph short lengths in without disturbing the fastenings too much - perhaps just in the first timber (assuming she's built on steam-bent frames).
Then chop out the rot in the fashion piece to establish its extent and to see if the rot has affected planks that seem good from the outside where they sit on the fashion piece. It looks likely that you'll have to remove about the top two-thirds of the fashion piece. The purpose of the fashion piece is to stiffen the transom and to provide a landing for the plank ends – but it doesn't necessarily have to be in one piece, so it's OK to make a butt join to the remaining third if that is sound.
If there's rot in the end of the transom beam, chop this out also back to sound timber.
Once the extent of the decay is fully apparent you can plan a repair. There's no point in repairing bits and pieces until you know the full extent of the problem.
With any luck, decay in the planking will be relatively minor and can be repaired as mentioned above, by scarphing short lengths in on two or three plank ends. Provided everything is dry, epoxy bond the scarphs one by on as this will not require a perfectly fitting scarph or excessive clamping pressure.
Then I would most likely laminate a new section of fashion piece, clamping the laminates to the planking a few at a time – find a laminate thickness that will bend nicely around the curve of the hull – probably 3mm - 5mm max. I would probably make the join to the bottom third of the existing fashion piece stepped about 100mm – so the butt join of the first half of the lamination was covered by the second half.
Depending a bit on how the laminates run, you might want to laminate the whole thing up in place (but wider) and then remove it so that it can be sided off to the correct shape. In which case, cover the inside of the planking and the join to the remaining fashion piece with shiny brown parcel tape so that they don't get stuck on.
Once you have the new section of fashion piece laminated and shaped, fit it back permanently – it shouldn't be bonded to the planking, just set on a good bedding compound and screw fastened. The join to the remainder of the fashion piece can be bonded or screwed.
If in any doubt about the condition of the bottom part of the fashion piece, make a whole new piece, laminated as above. You'll probably need wider laminates to get the compound curve out of.
Hopefully the end of the beam will just need a graving piece bonded in.
Making the new transom is maybe the biggest challenge as you have to get the shape pretty near perfect so that it fits inside the planking. I think I would make it in two layers of ply. The first layer with a vertical join down the centre, so that you can fit each piece separately. screw and epoxy bond the two pieces to the stern knee, fashion pieces and transom beam. The centreline join down the stern knee doesn't have to perfect as it can be filled with thickened epoxy.
You can make the second layer with a horizontal join (or joins) – whatever makes it easier to get a good fit to the planking. The curvature of the transom should provide enough pressure to epoxy-bond the layers together, with permanent screws into the fashion pieces, stern knee and beam.
While originally the planking was bedded onto the transom, along with the fashion pieces etc., it may be better now to use thickened epoxy (colloidal silica) between the transom edge and the planking.
Cheers -- George
To be truly free to live, one must be free to think and speak.
A C Grayling
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Originally Posted by Summertime of wight
