by GreenLake » Wed Aug 12, 2020 2:26 pm
From your picture it looks like the mast partners (opening in the cuddy deck) got damaged heavily.
In principle, this is just a hole in the deck (but with a reinforced rim). Position (and shape) of this are critical. Optics may be secondary. Adding it back stronger than what it was before can't hurt.
First job is to accurate mark on the deck some lines - with crayon or erasable marker that intersect the location of the opening, so that you can be sure it's in the right place after your repair.
Second, I would gind away the damaged area and sand around it, until you have a circular area around the hole that is flat and can accept a round fiberglass plate that has a new hole in it. (Same on the underside).
I would fashion a very accurate wooden plug that precisely mimics the mast profile and is about 3-4" tall. I would wax it heavily and nail it to the middle of a piece of plywood covered with a plastic sheet (like from a large ziploc bag or similar). This is your rig around which you can lay up the reinforcements that you will later glue to your deck.
I'm going to skip details of laminating technique here (see "The Epoxy Book" by SystemThree or similar literature, or ask detailed questions here if you are unsure, but for now, we assume that you know how to do this).
What you want is to lay up two circular plates (one after the other) that have a mast-shaped opening. You can make the upper one a bit thicker so it has a bit of a "collar" near the mast (about 3/4" wide). And both of them should be tapered a bit towards their outer edge. Do the bottom one first (for practice) and then the upper one (because that one should look neater).
When they have cured to where they are stiff enough to move, but not fully cured (green), you move them to the deck and glue them in place (using more of the same epoxy, or, if you want an epoxy glue like SystemThree GelMagic or T-88). You can use your "plug" to make sure they are aligned.
There may be some gap where the deck doesn't meet the opening, once the glue has cured enough to fix them, remove the plug and fill the gap with thickened epoxy (or non-sag epoxy glue), and reinsert the plug.
Note - the mast may not exit the deck at 90 degrees: you may need to sand one face of your plug so it assumes the correct angle when it's sitting on the plywood base of your jig. You will need to determine this angle with a stick poked through the deck to the mast step below.
After everything is cured, you try to step the mast. Use a coarse file to widen the opening just enough to make that process work (if too tight, the mast may stick). You may round the edges a bit etc. When everything works. Wash the epoxy with soap and water unless you used a "blush free" formulation. Sand any rough spots, esp. on the upper disk. Then paint (Epoxy doesn't like UV). For the underside, a cheap spray paint would do.
~ green ~ lake ~ ~