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PostPosted: Thu Mar 18, 2010 10:58 am 
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I purchased my H21SE boat last spring and had the best time sailing it. The hulls have always leaked and estimated 2-5 gallons of water each during a day’s sailing. When we sailed in January in 15-25 mph winds, the starboard hull filled up quite a bit more. We were in survival sailing and I think while we were putting the main down and holding the boat on the beach in large waves that the hull impacted a rock and caused a larger leak…..Doesn’t really matter as I am ready to fix the leaks and respray the gelcoat on the bottom. I am starting with one hull, but have similar issues with the port hull.

I need advice on how to fix the three areas shown in the pictures. The three areas are;

#1 Front trailer roller pressure point with stress fracture.
#2 Centerboard trunk edges with larger chips
#3 Rock impact and glass repair.

http://pbckt.com/sg.TLb

I cannot access the inside of #1 and #3 and do not need inside access to #2. For items #1 and #3 and using polyester resin, I understand that I need to grind thru the hull and use a backer of some type with wire to support from the outside. This will allow the polyester resin to have inside contact and not pop off if stressed in the future. I am used to using epoxy resins, but with polyester not being a “glue”, can someone describe the easiest solution to these two thru hull repairs?

The chips on the edges of the centerboard trunk are large and what would be the best way to repair these? Just build up gelcoat? Glass? Filler with gelcoat sprayed on top?

Any other recommendations?


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PostPosted: Thu Mar 18, 2010 12:22 pm 
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Working with polyester resin is virtually the same as epoxy. Roughen the repair surface and clean thoroughly with aceton or alcohol. Then do your lamination. Mixing is easier. Just add the proper amount of hardener, mix well, and apply. If you're off on the amount of hardener, it will just make the resin cure more quickly or more slowly, but it should still cure (if you're off with epoxy, it may never cure).

First thing you need to do is confirm where all your leaks are by doing a pressure/soap bubble test. The damage you show in your pics may or may not be leaking or there may be other leaks too. Best to find them all now while you're able to do the work.

I don't see why you would need to access the inside. Just grind out the damage, tapering as you move away from the crack, and then laminate your glass directly on the outside of the hull. If you've prepared the hull properly, there's no reason the repair should "pop off".

sm


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PostPosted: Thu Mar 18, 2010 12:39 pm 
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I don't see why you would need to access the inside. Just grind out the damage, tapering as you move away from the crack, and then laminate your glass directly on the outside of the hull. If you've prepared the hull properly, there's no reason the repair should "pop off".


Thanks. It was the guy at Fiberlay that recommend I get to the inside by means of grinding thru and then using the tongue depressor and wire trick for backing. It just sounded like the poly resin was not a glue as much as epoxy.

Would you use glass cloth, fibers or filler to cover the broken cloth fibers as shown?


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PostPosted: Thu Mar 18, 2010 2:15 pm 
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If you grind all the way through the hull to the point that there's actually a hole in the hull, then yes, you would need something on the back side to support the glass you're going to lay in. But if you leave a thin layer of existing glass, then you can laminate the new glass on top and build up from there. Hobies generally have a pretty generous amount of solid glass at the bottom of the hull anyway, so if you grind almost all the way through and then build back up to original thickness, I expect you would be good to go. Otherwise, you could do a blind hole repair as is explained in the Hotline archives. Basically grind all the way through, then laminate an inside patch. Glue it in and build your new laminate off of that.

In any case, you're going to want to use glass cloth for the repair, not just filler. Its always best to repair with like materials whenever possible.

Also you'll want to change your trailer supports so you don't have a repeat problem in the future.

sm


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PostPosted: Thu Mar 18, 2010 3:43 pm 
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Is the area around the hole soft? Is the glass cracked and has limited strength? If it is, you still need to grind back to a point where it's solid.

I pretty much agree with everything that's been suggested, and when I patched the hole in my hull I thought I was going to have to back it, but in the end I didn't. The actual hole was more of a 1/2" by 3" gash, but was still soft around the edges. I cut away as much of the loose glass as possible, and ground/feathered out a good two inches surrounding it. I then filled it in stages. First, instead of making the hole bigger and installing a backer, I forced a thick fold of wet glass into the gash. Then I ground down the exterior of the fold smooth, followed by layers of glass and cloth. Then you have to grind all of this down again into a shallow dish that's below the surface of your hull. If you don't, when you shoot your build up of Gelcoat, you'll end up with a wart on the hull. Just take a flat stick and lay over the ground out area to gauge if your repair is too proud...it's sounds like you may already know to do this... One other thing I did was taped around the hole to prevent excess glass getting on the hull and causing me more work.

My repair feels pretty solid. Is it as solid as if I were able to reinforce it with a backer? Proababy not. My situation was a also a little bit different as the hole was in the side and not the bottom.

As far as your other divots. You're going to be surprised as to what you can do with Gelcoat. If they're really deep you can mix some finely chopped glass into some thick gelcoat and fill the divot. If you pour some uncatalysed gelcoat out into a small container, it'll flash off and thicken up. Add your fillers, hit it w/ the catalyst and apply. Seal it with PVA, lightly sand out the area, then after it's set just shoot over it with your finish coat.

You're going to do fine!

Hell, once you get started you might decide just to sand and shoot the entire hull :lol:

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PostPosted: Thu Mar 18, 2010 4:10 pm 
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The area around the hole is very strong and I generally cannot make it flex. The glass is cracked but still has strength. As can be seen in the pictures, I have ground all the loose fibers away and should be able to just laminate above and have great strength.

Quote:
Hell, once you get started you might decide just to sand and shoot the entire hull


I was going too, but Jeremy talked me out of it. I am only doing the bottom. I was able to take down the gelcoat on the bottom very rapidly with an 18" flat board air sander. This faired out the bottom quickly and made it look nice, but I do not want to buff the whole hull if I can help it.

Sunny and 60 degrees today and I need to get this project done before I miss more sailing oppurtunities. :shock:


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PostPosted: Fri Mar 19, 2010 3:24 am 
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Hopefully we're not talking apple to oranges here, but any and all cracks need to be ground down to their core and faired out. I think this is what you've done, and I'm just clairifying. The cracks will come back if this isn't done.

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PostPosted: Fri Mar 19, 2010 9:08 am 
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Rockets wrote:
Hopefully we're not talking apple to oranges here, but any and all cracks need to be ground down to their core and faired out. I think this is what you've done, and I'm just clairifying. The cracks will come back if this isn't done.


More so than that, the fiberglass that is removed during the 'grinding out' process needs to be replaced with new glass laminated to the hull using polyester resin. You need to replace the damaged material in order to return the hull to its original strength. Grinding and fairing or filling with putty or gelcoat does nothing to bring back the strength of the hull.

sm


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PostPosted: Fri Mar 19, 2010 9:23 am 
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Yep, agreed.

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