HAIRLINE CRACKS

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JOEDEL@JUNO.COM

I HAVE A 1979 O'DAY MARINER, GREAT SAILING ! I'M TAKING IT OUT OF THE WATER FOR A NEW RUBRAIL AND NEED TO "CLOSE UP" OR FILL IN SPIDER-WEB AND HAIRLINE CRACKS ALL THE WAY AROUND THE DECK RIGHT AT THE RUB RAIL. I HAVE ALL THE BOOKS ABOUT FIBERGLASS REPAIR AND HAVE REPAIRED BIG HOLES BEFORE ,BUT WOULD LIKE ADVICE FROM OTHERS ON BEST FIX FOR NUMEROUS SMALL CRACKS . THANKS !
 
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TOM MCNAMARA

TYPING

please dont use all capital letters it bothers some people "a new commer"
 
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Justin - O'day Owners' Web

Fixing Cracks

Check out the archives for a couple of recent threads about fixing cracks in the gel coat. My one piece of advice is to make sure you deal with whatever stressed the fiberglass enough to crack the gel coat before you fix the cracks themselves or they will reoccur. Justin - O'day Owner's Web
 
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david lewis

From reading I have done on the subject there are two types of gelcoat used on boats, one is more brittle than the other but probably cheaper or maybe resistant to damage. Anyway, the gelcoat is a brittle material that is subject to the strains that the boat is seeing due to applied loads. While the GRP can deal with these strains the gelcoat is likely to crack or craze. This does not necessarily indicate any kind of structural problem although it may. Reinforcing the local area could cause the hull to flex more in another spot and just move the problem. I'd try to find a less brittle gel coat or maybe use an epoxy with a coloring agent to fix the area.
 
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LaDonna Bubak - CatalinaOwners

Don't bother

You're going to spend far more time & money than fixing those little cosmetic cracks are worth. I did this and even though my boat looks great now, I wouldn't do it again. It took a lot of work grinding those puppies out, filling & fairing them, and then painting the entire boat. Don't bother. If you just paint over them they'll come back. And you'll get more eventually anyway cuz it's an old boat. Leave it alone & go sailing! LaDonna
 
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R.W.Landau

gelcoat thickness

Joedel, Justin is right. There is much written on the subject. One reason for gelcoat cracks is that it was applied to heavy during construction. The gelcoat was sprayed into a mould. May times if the operator was not paying attention, or had trouble getting gelcoat into a corner, he would over spray the gelcoat making it too thick. Polyester resins are brittle. They gain their strength through the cloth or matt that it is laid up with. In the case of polyester resins, more is not better. It must be a close to perfect balance resin to reinforcement. The gelcoat relies on the mat that is directly applied to it in the next layer. When the gelcoat thickness is to great, is has no strength or reinforcement to transmit the load and therefore cracks. My advice, If they are minor, ignore them. If you want the boat pristine, fix them. If you are not painting, there is a very small chance that you will be lucky enough to match the gel coat perfectly in color.That may help your decision. If the fiberglass near the cracks is spongy, it is a structural problem. Fix the structural problem, then decide on the cracks. If you can't find info ask again. Please,let us know what your doing. r.w.landau
 
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Bill Lucas

No easy fix

will require gringing each one down until there is no more crack visible; then depending on how deep you had to go fairing or re-glassing; sanding and re-gelcoating; sanding and polishing. a lot of time and a lot of sanding. can be done but not an easy task; then there's the problem with color matching. And more than likely they will return!
 
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Andre Cornelis

Hairline crack under rubrail

Allright, the bad news first. It is a long and tedious job. My Mariner is a 1967 model so maybe your gelcoat is chemically somwhat different. There is a thread with this message that states that you remove cause of the stress that causes the cracks. Don't bump into anything anymore. The Mariner rubrail is a very weak area. The Mariners Owners Association published some articles on repairing the fiberglass under the rubrails. The articles deal with a severe form of damage but if the cracks in your Mariner as as deep as the cracks in my Mariner's rubrail they will apply. I had to grind the little flange down to half its original thickness in order to get down to undamaged fiberglass. My home email adress is ATHLC@msn.com. If you send me your address or email address I will send you the articles. I have come up with a methode to reinforce the rubrail area but am reluctant to put it on the board till I am more confidant of it's effectivness. To grind down the gelcoat I used a common 4 1/2" diegrinder with a light touch. It creates a hell of a mess. Good luck.
 
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