[img]I purchased a '95 Nacra 5.8NA three years ago on the recommendations of members of this forum. Great rec!
I store the boat on a beach w/ sand anchor but unfortunately high waves recently tossed it around. Impact with a metal fencepost left a ~3inch gash on the outside starboard hull, about 6 inches from the tip of the bow. Parallel to waterline. My guess is that the damage is irrelevant structurally given location. That right?
How to fix? I think I can see foam, looks as though I am through the fiberglass. Can I just fill/epoxy? Or does this require a fiberglass fix? I have experience in neither but am willing to learn
How repair 3" hull gash in Nacra
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Posted: May 17, 2018 - 12:03 PM
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Posted: May 17, 2018 - 12:18 PM
This boat is indeed foam core. Make sure the advice you receive from the "experts" know this.
Add a picture of the damage.
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Philip
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Posted: May 17, 2018 - 12:22 PM
Pictures would be helpful.
Generally speaking, if you damage the fiberglass (the actual fibers themselves), then you should use fiberglass in your repair. Straight resin (epoxy or polyester) has good shear, compressive, and bond strength, but very little strength in tension. So if you just try to fill in the damage with thickened resin, there's a good chance it will crack out again in the future.
A quick overview of the repair process for damage to the outside surface of the hull only (not into the foam or inner glass layer) - remove any loose material and grind back the gelcoat/fiberglass around the damaged area. Taper/feather the ground out area about 2" all around the crack. Cut out repair patches of fiberglass cloth to fill in the area. Each patch should be successively larger than the next. Wipe the repair area with acetone. Mix up your resin (very important to measure accurately and mix thoroughly). Wet out the area with resin and apply the glass patches (1" wide disposable brushes work well for this). After the resin cures fully, rough sand the repair area. If you don't care about cosmetics, you can stop there. If you want it to look good, overcoat the repair area with putty (Formula 27). Sand smooth using successively finer sandpaper grit. Finally, coat with gelcoat or paint.
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Posted: May 17, 2018 - 12:27 PM
It would be nice if you could do most of the repair from the inside of the hull, but that seems unlikely given the location. If you could reach the repair area by removing the deck then that would be best. The reason is that doing the repair from the outside of the hull means a very large area to fair in to make it look good.
But I suspect that you will have to do the work from the exterior of the hull. The first thing to remember is that you will have to grind back a bevel that is 12 to 1 the thickness of the skin that is damaged. So an angle grinder with some very course paper, or maybe an orbital sander with the same kind of grit. I would recommend doing the repair with epoxy, it is very strong and bonds well to the existing hull. West systems has lots of good info on doing these kinds of repairs and their setup with the pumps is great for small repairs like you get to do.
https://www.westsystem.com/products/
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dg
NACRA 5.2 #400
This End Up
Original owner since 1975
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Posted: May 17, 2018 - 12:46 PM
When I made this response above, I was aware the hull was foam cored. Working from the inside is always preferred, because the work to get the hull back to fair is much simpler. Replacing core is just another step in a repair like this followed be reglassing the interior skin.
Access is the key here. If you have to do the work from the exterior you need to turn into a body and fender specialist, or make friends with one. Otherwise you will be looking at this repair for a long time to come.
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dg
NACRA 5.2 #400
This End Up
Original owner since 1975
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Posted: May 17, 2018 - 01:24 PM
I'm no professional but my DIY skills usually hold up alright. Here's now I repaired a Prindle 18 bow sized hole in my H18 which also is foam core.
Cut an access hole in the deck with angled cuts to when I resin it back on it doesn't fall in.
Cut back the hull to where the foam core was undamaged and glassed in like 7 layers of 6oz cloth on the inside with about 4-5" of overlap to the rest of the hull.
Filled with thickened resin with some chopped up glass strands I cut mixed in.
Put on layer of ultra thin 2oz cloth on the outside just in case the resin tried to break loose.
Color matched the gelcoat as best I could and sprayed it on with the purple harbor freight gun.
Edited by tamumpower1 on May 17, 2018 - 02:26 PM. -
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Posted: May 17, 2018 - 01:54 PM
If the damage is just reaching the core, I would take a dremel and grind out a smooth transition between the gash and good fiberglass. Then clean the area well with acetone. Then apply West System 105 (mixed with 206 slow hardener) to the repair area using a foam brush. Then place a piece of fiberglass that is smaller than the repair area over the repair while the WS is still wet. Then wet out the glass with WS using the foam brush. Then apply a piece of glass the same size as the repair and wet out again. Sand once the repair has hardened. Fill low spots with WS mixed with fairing filler. Sand. Paint. Polyester resin is cheaper, but polyester resin does not bond well to cured polyester (Nacra hull material). West system epoxy will never disappoint. -
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Posted: May 17, 2018 - 02:23 PM
+1, use vinyl ester resin at a minimum. That's what I've always reached for even though I have gallons of epoxy on the shelf as well. Just depends on what kinda load the repair is taking. I mostly stay away from poly because it absorbs water like a sponge.
UScomposites has great stuff and you get the experience of having some money left in your wallet unlike buying West -
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Posted: May 17, 2018 - 03:03 PM
Appreciate all of the help. Here are a couple of photos. Two questions:
(1) I would love to sail a couple of times before hauling it off the beach to repair. That foolish? Am I going to cause further damage if I immerse it? Expect it will leak a ton, or does the foam dramatically slow the ingress of water?
(2) Any changed opinions on easiest best repair approach given the pics?
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Posted: May 17, 2018 - 03:30 PM
Meh that’s nothing. Worst thing would be for water to start getting into the foam core and spread and cause delam in other areas. If you want to sail it just drizzle some resin into the area to seal it up. That doesn’t really look bad at all. A complete repair you’d need to grind down a bigger area so you can lay a few layers of cloth on it and regelcoat.
My nacra had a 2” cut in front of the front beam in the worst spot and the previous owner had been sailing it for years with just a piece of tape keeping the water out lol. -
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Posted: May 17, 2018 - 06:22 PM
I have a similar gash in my bow
self inflicted ... mystere on mystere cat fight in my yard ... (and i lost)
i think the type of solution needed depends on if you have broken through the inner skin / to inside the hull
if so you must seal it all up in there (the inside)... however you do it - otherwise moisture will get into your foam ,...
if it's not burst through you can carefully prep the wound and load it up with epoxy and glass - or similar
sand and gelcoat over that and depending on your skills ... maybe invisible -
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Posted: May 17, 2018 - 07:06 PM
You could do a quickie repair to get you through a couple days (or probably the whole season). It’s really not that bad. I would get some 80 grit paper, knock off any loose material and rough up the surrounding area. Give the area a wipe with acetone. Then cut one or two patches using 1/2 oz fiberglass mat. Mix up a couple ounces of polyester resin and put the patches on. If you mix the resin “hot” it will kick in a few minutes and be sandable within an hour. Give it a rough sand with the 80 grit and you’re good to go. You could do this down at the beach (you certainly would not be the first cat sailor to fix a hull on the beach). Just be careful to keep sand out of the repair.
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Posted: May 17, 2018 - 07:48 PM
Guys thats barely into the glass, looks like gelcoat only to me. I'd fair/fill with a little bondo and hit with some gelcoat and go on my merry way. Of course if its deeper a little glass patch isn't a bad idea. -
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Posted: May 18, 2018 - 07:50 AM
You are lucky, usually once the waves meet a beach stored boat things get a lot more nasty. -
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Posted: May 21, 2018 - 12:46 PM
I agree, wet it out with epoxy for good adhesion and penetration, and then fill with thickened epoxy. Fair until you find it acceptable. Then, the easiest finish is to spray with Rustoleum or Krylon epoxy spray paint for appliances. Color is either Biscuit or White. Done. You do need to cover the epoxy resin and filler with the paint or gelcoat, or the sun will break it down.
Edited by mookie on May 21, 2018 - 12:47 PM.
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