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Discussion Starter · #1 · (Edited)
Hi everyone. I'm new to this forum and it sure looks like this is the PLACE to get boat repair information.
I have recently purchased a 1963 GRP Silhouette sailboat. I am going to try and completely restore the boat. I have begun to sand off the old finish, so far I have got the hull sides from the deck down to the waterline and the transom sanded. I used a random orbital sander and 40 and 80 grit.
What I have found so far is that the surface is cracked and crazed fairly extensively.I would say that the
gelcoat is essentially gone. Would it be better to;
1. Use a fairing putty to fill and smooth the surface then use a high build
primer and paint? I have heard Pettit makes a good one.
2. Coat with epoxy? West system or other.
3. Put a layer of say 1.5 oz. fiberglass cloth and resin? Polyester or epoxy?
Thanks
John
 

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poppy
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john, if the gelcracks are deep try to use a dremal tool or simular tool to grind out the cracks .if you don't no matter what you do they will only return. once you have them ground out ,use a good marine filler then sand smooth.this is what i do for a job. but remember they are not structual it is just the gelcoat . unless hull has been damaged in some way. good luck charlie
 

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Telstar 28
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IF it is just cracked gelcoat, there's no reason to put a layer of fiberglass down. Just open the cracks up a bit and fill with MarineTex or other thickened epoxy. Either paint or gelcoat the epoxy once it is cured.
 

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if the whole hull is crazed i would sand it with the 80 grit like you did. then mix up some epoxy and colloidal silica, and roll on a a few coats, then sand smooth. sanding will be tough using the silica but it will be a strong coating. you will have to paint the boat after wards or the epoxy will not hold up in the sun.
 

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IF you decide to go the route scottyt suggests, I highly recommend getting the epoxy as fair as possible before it cures. :)
 

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jhoward60, When following any of the good suggestions above, I would add the process of a shallow round drilled hole at the end of all or at least the larger cracks. This will likely distribute the stresses that might cause the crack to grow in the future. This is especially a prefered step it you are using the faring material as opposed to a new expoxy layer.
 

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as dog said you would want it as smooth as possible, the silica will make the epoxy hard as hell. you could also use a light weight fairing filler after the slica filler to make it easier to fair and sand.

the reason for the silica filler is it will make the epoxy structural instead of just a weak coating.

if you wanted to go crazy, there is some exotic fillers for epoxy that give it various properties. like ground up neoprene for extreme flexibility.

basicly you want a coating that has some strength, not just a coating. but you could also spray or roll on more gel coat, with the last layer a finishing gel coat, or sprayed will mold release to get it to cure completely.
 

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Discussion Starter · #8 ·
Thanks for all the good information. I'll probably go with the epoxy coating. I've got some pictures of the damage but I can't post them for some reason.
 

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You have to have ten posts before you can post a link to a photo as an in-line part of a post. :)
Thanks for all the good information. I'll probably go with the epoxy coating. I've got some pictures of the damage but I can't post them for some reason.
 

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A New Adventurer
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Not to hijack, but I have a spot 1' x 2' that is cracked like that. The PO tried to cover it with some house paint, but didn't do a good job. I'm going to sand and fill with epoxy next week, but the real question is what should I cover it with? I have never sprayed gelcoat and I'm a little afraid to. Would paint blend in well with the good gel coat of the rest of the boat?
 

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Paint is never going to be as good as Gelcoat or really look like it...but if you get the color right, it will not be very noticeable. :)
 

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A New Adventurer
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Awesome! That is what I thought, but given how off the PO fix was, I didn't know if it could be done better.

Thanks as always!
 

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okay after looking at the pics... wow

i would get a plastic spreader and mix some of the west system 406 filler, the silica stuff here to a peanut butter thickness and spread a layer in to the cracks. this will fill them with something that has some strength, but is hard to sand, make sure you dont leave any real high spots. then sand any high spots, then mix some more to the thickness of mayo, and roll it on with a fine foam roller, this will give you some build up. once again hit any real high areas with sand paper, then use west 410 filler this stuff to a thick paint consistency, and roll it on every where you dont want non skid. the reason for this is you wont need to sand it under non skid, it will hid it. you will need to do a light sanding, but be gentle you will sand thru it fast. then do a second coat with the roller. when it cures start sanding gently, with a sanding block. when you find a low spot mix some more but thicker and use a spreader to fill it. then sand again, when you are happy paint with choice of light colored paint.

this will about a gallon maybe a little more ( more if you need to the sides too )for a 30 foot boat which you did not say how big you boat is. it will probably take 4 days of nice warm weather, if colder use a faster hardener. you would be smart to do one half the boat at a time. let the first half cure while rolling the second half, then sand the first while the second cures. if you time it right you will have about a 4 hour rest, between the first and second coat of the day with the second coat curing over night.

if doing the hull too, you can work non stop by doing sections and while it cures move to the next section. if you are careful with the 406 filler and not leave and real high spots with the hull too i would say 5 days.

when done you will have a nice hard smooth finish that should last 20 years. the nice thing is the 406 will be ding resistant and the 410 only acts to smooth it out, but is softer
 

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after looking at the rest of the photos, cute little boat. i would say a gallon will be plenty with some left over, and i would use just the epoxy and 406 below water line. i would also put 3 coats to act as a barrier coat, and if you are going to keep it on the trailer and not in the water you can tint the epoxy to look like paint. then you can use less bottom paint, but you do need to paint it.
 

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Jhoward—

I've ordered fiberglass cloth from them, but not epoxy. I'd bet their epoxy is okay though, given their business.
 

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Discussion Starter · #18 ·
One more thought. Would it be of any benefit to use a layer of 1.5 oz. glass cloth with the epoxy, After I get the cracks filled and sanded?
 

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Why bother... just more to sand and fair then... unless you want the finish to show a fiberglass cloth pattern???

One more thought. Would it be of any benefit to use a layer of 1.5 oz. glass cloth with the epoxy, After I get the cracks filled and sanded?
 

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One more thought. Would it be of any benefit to use a layer of 1.5 oz. glass cloth with the epoxy, After I get the cracks filled and sanded?

as SD said nope. the glass would give it some stiffness, but thats not what you want or need. the colloidal silica will give it hardness, which the glass will too but not as well.

glass reinforced plastic ( what your boat is ) is 2 things... fiberglass and resin. the strength comes from the glass, the resin is a binder. in your case the silica will give the epoxy strength, which by it self it has but the silica will give it hardness and strength.
 
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