UPDATE!
You all probably thought I'd disappeared! The
weather didnt cooperate this spring, so I finally dug into this repair over the 4th of July weekend. It was a 3 day weekend with no chance of rain...perfect! What I was most afraid of was cutting into it, running into some delay, and then a thunderstorm popping up. I had tarps handy in case but some water would have inevitably made it to the cut. By this time I have also had some practice working with epoxy through my potting of the handrail holes on the other side of the boat, and having read as much as I could to mentally prepare figured it was time to get the show on the road!
The area was about 5 feet long by 1 foot wide (1 gallon of epoxy ended up being enough, but there wasnt much leftover. I have a gallon of polyester resin I'll be using to glass the seams later.). I used clues from the sound I got tapping the deck, and by digging around in the holes where the handrail was mounted to guess how far the wetness/rot extended. Time to cut it open!
I used a circular saw for a consistant
depth. The tyvek suit I got on amazon for $7 was pretty handy. Kept the
fiberglass off, and the sun too!
Prying the top panel off war a real chore, but slowly it came up.
Once I got to the very rotten section toward the middle it came right up easy. The edges where it was merely damp was still firmly bonded to the balsa. A thin layer of the
fiberglass tore off from the top sheet and wanted to stay with the
wood there.
After
cleaning off as much wood as I could with the chisel, I used a 4.5 inch angle grinder with a flap disk (something like this thing:
Diablo Steel Demon 4-1/2 in. 60 Grit Coarse Grinding and Polishing Flap Disc-DCX045060N01F at The Home Depot) to grind the bottom and the top
sheets smooth. It made quick work of it. I also cut my core material to fit the hole at this point. I dug out all the wood that I could reach on the
outboard side of the cut since most of the water and
rot was on that edge. I got a bit too carried away, probably removed wood 3 inches back and it was hard to fill the gap with core material but I did my best and ended up pumping alot of epoxy down there to fill in the gaps.
I wiped everything down with some acetone that I got from a auto care shop thats clean and made for using with resins. Time to mix up a ton of epoxy! I used a slow hardener to give me plenty of time to work the area. <--Important! I didn't have a good system worked out for mixing larger amounts than I was used to. I only had 20ml syringes and plastic cups and spoons. Should have probably used a larger graduated container of some sort. Luckly my lovely lady was there constantly mixing up cup fulls while I was applying it to the deck.
For the core I used some divinycell foam. It was the only suitable core that the local plastics supplier had available. It was probably twice as thick as it needed to be and was a real pain to sand down to the proper thickness, so invest some effort into finding out exactly how thick your core is so you can buy a matching thickness.
I started at 830am and by 700pm I was finishing up. Still
cleaning up while the fireworks start going off!
Try to be careful with the epoxy! Its very hard to not make a mess. I used rocks from shore to weigh down the top sheet after I put it together, and one of them ended up glued to the boat! Luckly it was only touching near the seam. I crowbared it off the next day and it took a bit of
gelcoat with it!
I still need to do the beveling and glassing of the seam, but after confirming that the edges were well sealed, decided I could do that later since its waterproof at this point.
Phew, certainly a long day!