need help/info repairing fiberglass hull

CanadianDave · #1 (**permalink**) 06-19-2011

Hi guys/gals

my father in law has a 16 ft fiberglass boat that a brother in law beached last fall and punched a hold in the bow below the water line. there has been talk by some of the family to repair the damage using automotive fiberglass repair kit. I've done some reading about west marine system but I'm not 100 % sure what I'm looking for.

can someone link me to a site that would have a complete kit available in Canada?

thanks

Dave

this is what I've been looking at but the hole is 1 3/4 wide and 4 inches long. would one kit be enough to repair and cover say a 3 inch over lap of the damaged spot. and would 3 inch over lap be enough?

WEST SYSTEM G/Flex 650, 8 oz. (One 4 oz. bottle of resin, one 4 oz. bottle of hardener) at West Marine

I've done a lot of fiberglass work on automotive but never on boats. well we have fiberglass several old wooden hulls but have always used automotive kits.

Sabreman · #2 (**permalink**) 06-19-2011

Personally, I'd buy a quart of West epoxy, fast hardner, and some fiberglass cloth. You don't need much more except a mixing container, some gloves and tape. Taper the existing hole at least 8:1 (12:1 is better) and use several layers to build up thickness, allowing each layer to harden in between. Apply the first layer on the inside of the hole and overlap the hole by about 3" all around. Color the resin on the last couple of coats so that final sanding doesn't go through the color. You may wish to make the "final" coat without cloth, using West collodial silca as a thickening agent. I personally don't like West fairing compound for below the waterline repairs because it will absorb water.

Don't worry about having excess epoxy or silca left over. I always keep a supply in my shop and use it for a variety of projects around the house and boat.

Do not use automotive repair kits for below the waterline repairs. West is the way to go.

SlowButSteady · #3 (**permalink**) 06-19-2011

On a small boat like that, it's a relatively easy fix. A bit of glass cloth, a bit of epoxy, a bit of sanding, a bit of paint, and it will probably be difficult to see the repair when you're done. If you do decide to fix it, you might want to take a look at these guys rather than West System. They have good products at good prices, and quite a bit of info on their website (albeit in a somewhat disorganized format).

JimsCAL · #4 (**permalink**) 06-19-2011

The "auto" kits will use polyester resin. Epoxy will give you MUCH better adhesion. You don't want the patch to pop off miles from land.

TQA · #5 (**permalink**) 06-20-2011

Just remember it is best to lay things up so that a layer goes hard but DOES NOT CURE completely. Inother words try to do it all in a day or two. That way you get layer to layer chemical linking.

IMHO West system is the way to go.

epistosaurus · #6 (**permalink**) 06-20-2011

For larger boat and best longevity I would concur with others to go with epoxy resin (not necessarily West System. I've been using a canadian-made East System and am very happy). But you can as well go with polyester resin which will be cheaper and you can control the speed of cure with hardener amount. Just do not use Bondo (automotive poly resin) get marine stuff. Good poly resin/hardener is about 40% of good epoxy. Your current hull is almost surely polyester-based. Polyester resins are more susceptible to osmosis, though that may not be a worry for you if you trailer the boat regularly or sail fresh waters, and in any case we are talking potentially many years down the road.

junkrig · #7 (**permalink**) 06-20-2011

I would strongly disagree with anyone who says polyester is ok for repairs. Polyester boats cure strongly to themselves by molecular linking but this required that all layers are laid up before the first layer cures. Once that final cure has set polyesters have very poor secondary adhesion.
Epoxies have very strong secondary adhesion and are the only way to go for repairs. Personally I am partial to Gflex for bow area repairs because it's more flexible than most epoxies, but either way you choose be sure to choose an epoxy.

epistosaurus · #8 (**permalink**) 06-20-2011

I did not really want to start any resin wars here -

that's for sure. And I do think epoxy is better for repairs, as I stated already.

But.

From what I remember from reading D. Casey's book, polyester does not really fully cure when constantly exposed to air, and that secondary poly-poly adhesion is over 70% of original strength from some studies. Is that true? I know pple who poly-repaired their hulls in larger boats and sailed them hard for years without any problems. Some pple prefer poly repairs so as not to create hard-spots in their hulls, though something like Gflex would probably alleviate that problem.

Not sure how that particular 16ft sailboat is used, but I cannot imagine that well done poly repair would not hold up in that case.

mitiempo · #9 (**permalink**) 06-20-2011

Most yards doing a repair to a glass hull use epoxy -so there will be no doubt of its adhesion in the future and they don't want problems down the road.

There are many kinds of epoxy and they all will work. I use West and have for over 20 years but I know it is more expensive. I like the convenience and have the pumps so measuring is not necessary. I find epoxy much easier to use than polyester as well. For the amount you will need the price isn't a huge issue.