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frowley

Hull fracture, etc

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Peg and I attempted to sail out of Boat Harbor, Port Townsend a while ago with Deluge (CS17.3), which involves negotiating a very narrow channel bordered by a jetty, in our case, with the wind on our nose and no outboard. Short story is we foundered and hit the jetty -  and retreated, (which involved me jumping overboard and pushing us back out into the channel). After a quick review of the boat, I figured our egos took the worst of the damage. The CB leading edge had a few scrapes, but the hull seemed fine. I've since had the boat out in a 15-20 knot crossing of Puget Sound through some nasty chop in which the hull took a real pounding. Again - all good. Today though, I just discovered some delamination on the cabin sole, and a hairline crack on the outside of the hull - hopefully discernible in these photos:

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About 4 " to the right of the keel you can see a hairline crack. The inside, 2nd photo, shows the delamination and broken fibers.

 

My plan is to sand about 10" square around the crack on the outside, then layup a 6-8" square of 10" fiberglass cloth, feather the edges, and paint. On the inside, this may be overkill, but I'm thinking I'll sand out and patch the delamination, then layup a layer of kevlar over the entire, exposed, cabin sole. We were drifting when we hit the rocks, never really able to get way on. I suspect the damage occurred when the keel, which must have ridden up on a rock, slipped off of it, bringing the weight of the hull down on the rock. Pretty sure the ballast tank was full, so that's a lot of weight. 

 

Does my approach seem reasonable? Better ideas? 

 

While I was under the boat, I also discovered this:

20190712_153709.thumb.jpg.d25e036854b851ed6b7f661efe3831f6.jpg

I haven't gotten the board out yet, but this is definitely a failure of the butt joined centerboard segment I'd added to bring the length up to current specs. More on this after I get the board out, but for now, my plan is to sand it back well beyond the segment and tip, and lay it up possibly with a light weight kevlar and a light weight glass over the top of that to keep from going crazy managing the kevlar. If this happened during our jetty mishap it certainly wasn't visible. But perhaps we weakened it? 

 

I embedded several carbon fiber rods I had laying around the shop before laying up the board - I suspect they're what's holding it together at the moment. Again, let me know if you have any thoughts or advice on my repair. I'm not really in a mood to build another entire CB unless Alan or Graham think I need to. 

Fred

 

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Not entirely following the sequence of events, but sanding back, faring in new layers is definitely the way to go.  Must have been scary.

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Thanks Paul - it was really a drifting non-event that was more embarrassing than anything else. 

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Hi Fred,

 

Fortunately it is an easy fix. For the hull bottom, you need to grind the glass back to the bottom of the crack and same for the delamination, then relaminate it back. Kevlar has great abrasion resistance which I would consider if I was intending to be scraping the bottom on rocks. The local loading can be considerable when a boat is lowered gently onto a rock but in a dynamic situation I am surprised by how little damage there is even if it appeared to be not a heavy duty situation. You certainly mitigated the damage by jumping into the water, I am glad that you did not get damaged. As for replacing the inside with kevlar, I don't see the need to go beyond glass. Even with a much stronger inside skin, if it delaminates you do not have anything. Grinding back to sound wood and relaminating back with glass should be good. You can add some extra layers of glass if you like as it won't cost much or be hard to do or add weight where you do not need it.

 

As for the board, you do not need to replace it. I would grind down say 1/4" at the joint to a 20 : 1 taper and build it back up with layers of glass until it is fair. Carlita's butt join in her board is still going strong.

 

Good luck with the repair.

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Thanks Graham - really appreciate your responding with sound advice. I love the taper idea, and will just stick to glass and forget the kevlar.

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