Monday, July 11, 2016

Glassing The Ribs

Riding the momentum of getting the ribs installed, I was able to start glassing over them as well.  I'm just shy of half way through this phase at the moment.  Many nights were spent while falling asleep trying to figure out how best to wrap the cloth smoothly on those bends.  I think this is where vacuum bagging would be nice, but I'm not equipped for that kind of thing so I needed a lower-tech approach.

The small ribs had a larger radius on both sides, so I was able to massage the cloth into shape and then trim it even.  The fit ended up perfect, and I'm really pleased with the result.

The inboard ends of the ribs along the centerboard trunk were cut off square with an approximately 1/2" round over that proved a bit more difficult.  I ended up slicing it down the center and wrapping.  It worked OK on one, and got rough on another.  I may just sand the rough spot and add a small layer to cover it.  The structural element is really my concern here, but having the top open to the weather allows water inside the piece, and will encourage expansion and contraction of the cedar.  A good laminate will better seal it, and extend its life.

Despite my best efforts I had a few spots which I couldn't seem to keep firmly pressed against the wood, visible in the above picture as being lighter colored.  I kept brushing resin into them, but it didn't seem to work.  I think the 8oz cloth is just a bit stiffer than the 6oz which seems lie flatter.  I suspect this will go away if I add a second layer, which I'm still debating.

Which leads me to the laminating schedule.  The original ribs I removed seemed like about 3 layers of 8oz cloth in thickness.  Possibly two.  Definitely thicker than the single layer I have on now.  The other observation I made was that the ribs appeared to not be bonded to the hull, and definitely had no fillet, so the laminate was all that was holding it.  I used a much stronger bonding approach, which would reduce the laminate's structural responsibilities.  I've also observed a bunch of Lightnings who had a single layer of 6oz cloth over the ribs, certainly less than what I've got now.  So what to do?

I suspect that structurally the single layer I've installed is sufficient to the task at hand, and after checking with the Classic Lightning Yahoo Group my suspicion was confirmed.  It sounds like the glass is really optional for a properly bonded rib.  At this point I plan to make sure I've got good coverage on the 8oz cloth, clean the blush off, and give it one more light resin coating to help fill the texture and ensure full moisture blockage.  We'll stick with one layer of 8oz cloth.

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