A friends boat has a small crack on the outsided of the port hull. The crack is above the water line and is maore than just a crack in the gel coat, as there is also a soft spot associated with the crack.
I know this boat is solid fiberglass so I assume the injection method will not work. My thoughts are that new fiberglass is needed to repair this. I also assume that the best way to do this is to build class from the inside, but I do not know how to access the inside of the hull where the crack is. It is about six inches behind the bridle foil. The boat owner does not want to install a port in front of the crossbar due to horror stories of the catastrophic hull failure with forward mounted ports.
I guess my biggest question is can this be repaired from the outside?
It was a great day to sail in Tuscaloosa though. Turned the nacra over in an unexpected gust and all the ski boats thought we were in real trouble. We quickly had a crowd watching us right it with a few asking if we were ok. Guess they don't see many catamarans.
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Griff
Hobie 16
Tuscaloosa, Alabama
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Nacra 5.8 Hull
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Posted: Jun 04, 2011 - 04:51 PM
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Posted: Jun 05, 2011 - 02:02 AM
- if the hull serial number starts with a T then it's a solid glass boat
- if it starts with an H it's a foam core boat
- the normal way to get in to a nacra hull if you don't want to cut a port, is to use some thin, flat metal, like scraper and a mallet to tap away at the deck/hull join until it separates. then continue right around the edge until the whole deck can be lifted off
-usually the deck can be rebonded on to the hulls after the repair is done, if it's not broken but, ends up looking pretty rough and needs lots of filling, gelcoat etc.
-so it might be best to try an external repair first but this will depend on the size of the crack and and soft area, if it's leak rate. pics would help too
-how big is the crack and soft area, any idea how it happened?
Edited by erice on Jun 05, 2011 - 02:06 AM. -
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Posted: Jun 05, 2011 - 10:48 AM
The soft spot is about the size of a softball. I am not sure how this happened, but I believe it was caused by the ratchet strap that holds it to the trailer.
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Griff
Hobie 16
Tuscaloosa, Alabama
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Posted: Jun 05, 2011 - 11:28 AM
West Epoxy Systems has a pamphlet on fiberglass repair. The specifically address through hull repairs when you cannot get access to the back of the area to be repaired. As I remember they recommend cutting out the area of damage and the from the front pulling a backer and epoxying it in place. One this is in place the final repair can be done from the outside of the hull. If interested I can try to find the West Epoxy pamphlet and fax you the appropriate pages on this type of repair.
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Scott
ARC 21
Prindle 18
Annapolis, Maryland
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Posted: Jun 05, 2011 - 07:38 PM
I have a short album in Tech Tips on this exact subject, but I see not all the photos are posted. It is very easy to fix a hole of that size.
http://www.thebeachcats.com/pictures/?g2_itemId=77105&g2_GALLERYSID=6160bc24121694333ccab710da9dbadc
Just cut out ALL the damaged area. With a softball sized hole, you should be able to reach inside, (wear good gloves) & grind away material. You want to feather away from the center of the hole. You can use an angle grinder on the outside to feather material away. Wipe everything down with cleaner, (rubbing alcohol or acetone) I then cut a piece of plastic from a juice jug that was as big as the first layer of glass matt. Poke a couple of small holes in the plastic & feed a length of fishline through. Cut 3 or 4 pieces of glass matt, each one smaller than the last. Stack them in the correct order, & feed the fishlines through them, you may need a needle. (I used a piece of stainless steel wire, but I think fishline would work as well)
What you now have is like a stack of waffles of decreasing size, the largest being the piece of plastic & first layer of matt.
Reach a gloved finger inside & wipe the area with catalyzed resin. Now rub resin into your stack of waffles till all layers are fully wetted. Fold the stack almost in half, like a taco shell, & insert into the hole. You will hold it by the fishlines, & when you let it go, the "taco" will unfold. Using the fishlines, maneuver it into place, then pull on the lines to hold the layers firm against the inside of the hull.
You might need a helper to hold a stick or two in place as you tie the lines so as to hold the patch in place till the resin sets up.
Clip off the fishlines, & add a few layers of matt to the outside, starting with the smaller circle & larger one(s) on top. Try not to totally fill to the level of the gelcoat. By leaving a 1/16" below the old gelcoat level, you can get a gel repair kit & add a final coat so the patch won't show.
It really is an easy fix, just be sure to be organized & have you waffle stack all made up, & test how you will tie it up before you mix up the resin.
That portion of the hull will be stiffer than the original.
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