Thursday, November 1, 2007

The keel seam, abridged

For the readers sake, I've decided to combine posts on the keel seam. Sorry, but there's no way to make that interesting! To promise something good, heres a few things we've got in store for later (read: too cold to epoxy) blog entries:

-partner box and shim system that works! No more gaping hole in the deck filled with wood and doorstops...
-re rigging the mast and boom, so we can bring the boat from 1964 to at least the late 90's
-soft dyneema attachments for just about everything. I bet theres 3lbs of stainless steel bails alone on this boat.
-new control line and deck layout
-much more

For now, Im still working out the keel seam. This has involved quite a bit of labor so far, and theres more to come. A large part of the time involved is my trepidation towards grinding too much. If I could do this again I wager the grinding would take about 4 hours instead of 12! The difference would be in taking off the right amount the first time, instead of chickening out and doing more then next day. Here is a play by play of the keel seam to date:

-strip the bottom paint (see earlier post) to avoid grinding and breathing the VC17
-grind around the keel seam, about 4 inches above and below. This is to make room for the biaxial tape.
-tightening the keelbolts. This part was fairly terrifying, as you're applying a lot of torque to 40 yr old bolts! I used the cape cod instructions and everything turned out ok. There was one bolt that had a broken bronze backing plate, so I ended up making one out of G10 laminate. Great stuff, very strong. I hope I never have to do this again though! Heres a photo of the backing plate before washer and nut. The goop is epoxy and 404 filler, which was squeegeed away before it set, but after full torque was on.
-applying the biaxial tape. This was great fun, especially after all the grinding. Nothing sophisticated here, just two overlapping layers of 15 oz biax cloth layed up hot. Here is the thrilling photo:

As you can see, theres a bit of resin dripping out the bottom of the repair. This is due to some fairly aggresive rolling of the laminate, and was easily cleaned up with a scraper. I figure better to waste some resin than have: a) air bubbles, b) too much epoxy. When all was done I had a nice smooth glass layer, which will hopefully be enough to resist the inevitable flexing that goes on in this part of the boat.
-fairing compound: I applied this hot, ie after the resin holding the glass resin had gelled and gotten tacky, but before it was cured. This means you can put up a couple layers in one go, and not have to clean off amine blush/sand. I used a ton of 407 filler, mixed with a relatively small amount of epoxy to get a very thick mix that hung well to the keel. Applied with a spreader this comes out pretty ready for longboarding.

Next step is to fair, using a longboard and 36 grit, then the inevitable reapply of fairing goop, then more sanding. After that I'll throw on about 4 coats of interprotect barrier coat and sand again, then VC17 in spring.


Keel seam:

additional 10 hrs