A couple of days have passed where it’s been too damn cold and wet to achieve anything outside on the hull, but I have managed to patch up the rotten old centre board. It was extracted reluctantly from its grave in the fibreglass casing and examined for defects.
As you can see it’s in a right old state. Its soaked up plenty of rainwater, swollen to the point where I had to hammer it out from below, and de-laminated around its edges due to rot. Its also got a small patch of rot at the top which is so bad I’m going to have to cut it out and glue a new piece in. Sounds like a lot of work but it wont take too long if I can remain indifferent to the cosmetic outcome in favour of strength and useability. Its also considerably less work than sourcing new marine ply and making a completely new board! This thing has been stored indoors for a couple of weeks to dry it out before work began.
Utter brutality is required again to remove all rotten edges of the board using the trusty flap wheel in grinder method. No sense in being gentle, get it all off the easiest way possible and see what you’re left with. The board has obviously lost some of its shape and surface area but it isn’t going to be noticeable in use. The trickier bit is going to be repairing the nasty rotten lump at the top edge. Luckily I can again thank the old mirror dinghy, which donated its rig and sails to this project, for providing me with some good pieces of useable marine ply. Namely, its dagger board and rudder.
I can now measure out a square that takes in all the rotten wood of my new centre board (6inches by 4.5) and mark it out on the good marine ply. I carefully cut this square out, placed it over the rot, drew around it and cut inside the lines with a fine toothed saw or jigsaw. The new piece should now be a tight fit into the hole, after a bit of edge sanding, and can be glued in with a waterproof wood glue or epoxy and clamped. A couple of bronze tacks or screws might be a good idea too but I didn’t have any in the shed. I made sure to use a square and straight edge when marking out my lines or the pieces would never fit together properly.
Not so shabby really. A good strong shoestring repair. Will seal the edges up with a bit of liquid epoxy and then slap some paint on the thing before refitting it.