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Old 05-03-2013, 22:26   #376
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Re: Nauticat 52 Refit

This is the tricky part, color matching. The rest is just chemistry and craftsmanship, this part is an art. Not everyone can be taught to do it, you have to have "the eye". But there are ways...
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Old 05-03-2013, 23:20   #377
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Re: Nauticat 52 Refit

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Yes, there would. WEST will tell you it can be done but don't go there unless you tie coat with a modified epoxy primer like 545 first, which defeats the purpose in most cases. Poly doesn't like to cure properly when exposed to amines. There are better ways to do that sort of thing anyhow. If you just grind and epoxy fill a stress crack it will eventually come back every time. I grind and glass all fractures and cracks with poly, glassing a little high, grind fair, and brush gelcoat as a primer. I use a good quality poly filler for little stuff. And for big stuff I will roll on multiple coats of gelcoat and sand it out fair like hi build.



In this pic there's a repair that's just been shot with color matched gel under the piece of blue tape. It's still wet. When it's been wet sanded and polished it'll look like new again. Gelcoat is more work to maintain, but at least it can be maintained, unlike paint. I suppose that's misleading, I shoot loads of paint blends too, but that is not really for the layman. I can show you how to shoot gelcoat blends like this without even using a gun or a compressor. Can be done anywhere, no special tools required.
I've read about dealing with the "anime blush" from epoxy and was a bit dubious it could be resolved by wiping down with plain water, etc. It seems more likely it would continue to work its way to the surface, thereby working against the bond b'twn. the epoxy underneath & the poly on top. But what do I know?!

Can you recommend a brand/type of poly filler for the typical deck issues I'm trying to repair? In your description of repairing the "big stuff," do you mean that you fill with gelcoat alone, or on top of a poly-based fairing compound? My topsides came to me with a beautiful awlgrip job which I know I'm going to have to assign to a pro pretty soon to touch up if not completely repaint. It would be nice if I could a least get a handle on maintaining if not improving the gelcoated decks.
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Old 05-03-2013, 23:49   #378
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Re: Nauticat 52 Refit

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I've read about dealing with the "anime blush" from epoxy and was a bit dubious it could be resolved by wiping down with plain water, etc. It seems more likely it would continue to work its way to the surface, thereby working against the bond b'twn. the epoxy underneath & the poly on top. But what do I know?!

Can you recommend a brand/type of poly filler for the typical deck issues I'm trying to repair? In your description of repairing the "big stuff," do you mean that you fill with gelcoat alone, or on top of a poly-based fairing compound? My topsides came to me with a beautiful awlgrip job which I know I'm going to have to assign to a pro pretty soon to touch up if not completely repaint. It would be nice if I could a least get a handle on maintaining if not improving the gelcoated decks.

Exactly. I've been paid to do it by people who insisted the west reps told them it would be fine. It never worked out. Once it was a very expensive mistake for someone. I was all "I hate to say I told you so, but...".

Sure. I use 3M Rage or Rage Gold a lot. Use Evercoat for filling pinholes or very small imperfections. A gallon of Rage goes a very long way. Rage Gold is better but the color can be a problem. Use white cream hardener instead of blue or red unless you are top coating with a cool or warm color. Use 3M Premium Filler below the waterline if you want poly there, it's a vinyl ester fairing compound. These products cure vastly faster than epoxy and sand much easier too. You just have to know how to use them, perfectly appropriate materials for good pro repairs.

I do mean that I fill with gel alone. It is tricky for the amateur to do a big layup fair enough to do it this way, but if you just remember to glass high and then grind fair, it will work out. This method takes more work than fairing in bondo and requires more skill, but it gives you a repair with no or very little filler in it. Just very thick gelcoat, just like the original part. It's when people start slathering on bondo a 1/4" thick that problems occur.
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Old 06-03-2013, 06:03   #379
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How exactly do you glass a hair crack or stress crack? My thought was to drill holes at the ends to stop it from spreading, then grind out with a small tool like Dremel, creating some surface area, then fill with epoxy + colloidal silica filler. If cracks return this is useless as in my case it is estatic work only, so I need a final solution.

It is my understanding that the cracks I have are caused by a vinylester layup with a polyester gelcoat. The hull doesn't have this, just the deck, at points with stress risers like fastener or hard edge in laminate. It's gelcoat cracks only, with good laminate underneath?!
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Old 06-03-2013, 08:07   #380
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Re: Nauticat 52 Refit

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How exactly do you glass a hair crack or stress crack? My thought was to drill holes at the ends to stop it from spreading, then grind out with a small tool like Dremel, creating some surface area, then fill with epoxy + colloidal silica filler. If cracks return this is useless as in my case it is estatic work only, so I need a final solution.

It is my understanding that the cracks I have are caused by a vinylester layup with a polyester gelcoat. The hull doesn't have this, just the deck, at points with stress risers like fastener or hard edge in laminate. It's gelcoat cracks only, with good laminate underneath?!

Get a 1" Roloc grinder setup and chuck it in to your fastest cordless drill. Triple tape off about 1 1/2" around the crack and then use the Roloc to grind off the gel up to the tape. If you have a right angle electric die grinder or even better a pneumatic with air, that's much better, but given your locale the cordless will work fine. Grind the crack till its gone, pausing to wipe with an acetone rag so you can see it. In the vast majority of cases where an owner tells me his stress fractures and spider cracks are only in the gel, they actually go well into the glass or even all the way through it. Chasing it out is the only way to know. This is why if you just grind the gel out and fill the crack it will return, because its actually a stress fracture. If you have lots particularly in points with stress risers, they are almost certainly fractures. Cases where the problem is actually restricted to just the gelcoat are extremely rare IME.
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Old 06-03-2013, 09:19   #381
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Re: Nauticat 52 Refit

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Get a 1" Roloc grinder setup and chuck it in to your fastest cordless drill. Triple tape off about 1 1/2" around the crack and then use the Roloc to grind off the gel up to the tape. If you have a right angle electric die grinder or even better a pneumatic with air, that's much better, but given your locale the cordless will work fine. Grind the crack till its gone, pausing to wipe with an acetone rag so you can see it. In the vast majority of cases where an owner tells me his stress fractures and spider cracks are only in the gel, they actually go well into the glass or even all the way through it. Chasing it out is the only way to know. This is why if you just grind the gel out and fill the crack it will return, because its actually a stress fracture. If you have lots particularly in points with stress risers, they are almost certainly fractures. Cases where the problem is actually restricted to just the gelcoat are extremely rare IME.
Is there usually then a cause & effect, i.e. some nearby deck fitting that perhaps needs a larger backing plate, for e.g.? Once remedied, would you want to lay down new laminate or just one of the fillers you mentioned previously?
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Old 06-03-2013, 10:03   #382
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Re: Nauticat 52 Refit

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Exactly. I've been paid to do it by people who insisted the west reps told them it would be fine. It never worked out. Once it was a very expensive mistake for someone. I was all "I hate to say I told you so, but...".

Sure. I use 3M Rage or Rage Gold a lot. Use Evercoat for filling pinholes or very small imperfections. A gallon of Rage goes a very long way. Rage Gold is better but the color can be a problem. Use white cream hardener instead of blue or red unless you are top coating with a cool or warm color. Use 3M Premium Filler below the waterline if you want poly there, it's a vinyl ester fairing compound. These products cure vastly faster than epoxy and sand much easier too. You just have to know how to use them, perfectly appropriate materials for good pro repairs.

I do mean that I fill with gel alone. It is tricky for the amateur to do a big layup fair enough to do it this way, but if you just remember to glass high and then grind fair, it will work out. This method takes more work than fairing in bondo and requires more skill, but it gives you a repair with no or very little filler in it. Just very thick gelcoat, just like the original part. It's when people start slathering on bondo a 1/4" thick that problems occur.

Oops, it sounds like someone wanted to save a few bucks on primer? Interestingly, West has some lengthy treatises & even testing that says gel over epoxy is OK, but then both 3M & Evercoat specifically warn against.

What about the gel paste they give you in those overpriced little "gelcoat repair kits"? Is the paste a faster but still appropriate way to build up the gel?

OK, here's a couple more DIY projects this thread has inspired me to put on my list. I'm only asking, mind you, because others apparently have not yet come to appreciate their obligation to prevent you from getting bored at work:

G10 for backing plates: I'm mainly thinking lifeline stanchions here, but also potential for swim ladder fittings, etc. No corrosion, strong as hell. If a good choice, then how thick to buy the sheets & is the stuff reasonable (for a DIY'er) to cut & drill.

"Flex-Mold" for molded-in non-skid: My instinct sees potential for disaster for anyone other than a pro using these, but I don't know how else to restore my non-skid gelcoat, unless it's feasible to use the grit that's commonly used with paint. Personally, I think the molded gel looks a lot better than any paint I've seen, but mine is getting slippery. In fact, I'm afraid to put anything on it at this point (e.g. compound or wax) for fear of making things worse.
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Old 06-03-2013, 10:50   #383
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Quote:
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Get a 1" Roloc grinder setup and chuck it in to your fastest cordless drill. Triple tape off about 1 1/2" around the crack and then use the Roloc to grind off the gel up to the tape. If you have a right angle electric die grinder or even better a pneumatic with air, that's much better, but given your locale the cordless will work fine. Grind the crack till its gone, pausing to wipe with an acetone rag so you can see it. In the vast majority of cases where an owner tells me his stress fractures and spider cracks are only in the gel, they actually go well into the glass or even all the way through it. Chasing it out is the only way to know. This is why if you just grind the gel out and fill the crack it will return, because its actually a stress fracture. If you have lots particularly in points with stress risers, they are almost certainly fractures. Cases where the problem is actually restricted to just the gelcoat are extremely rare IME.
I know, but all the Sundeers have it. My surveyor told me the gelcoat was incompatible with the vinylester layup. I just think they used low quality gelcoat. Anyway, like you write, only grinding will tell for sure.

So, after grinding, I assume wet out with resin and use cloth to build up? I think you use gelcoat for finishing? I hear that many use MarineTex, what is your idea about that? I used it once, matched color with the same pigments as for gelcoat and it worked much the same as gelcoat. May be it is no so brittle, I don't know. I do know my color matching sux
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Old 06-03-2013, 11:25   #384
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Re: Nauticat 52 Refit

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I hear that many use MarineTex, what is your idea about that? I used it once, matched color with the same pigments as for gelcoat and it worked much the same as gelcoat. May be it is no so brittle, I don't know. I do know my color matching sux
I did the same... looked great in the bright sun, but then the sun starting setting. Found out that I made it way too creamy of a color and it looks horrible now. Easy enough to grind out and try again.

Question about polyester vs Epoxy. Isn't the reason to use epoxy on a poly boat for the secondary bond that epoxy has? I had to repair some tabbing on our boat, and the local fiberglass guy wanted to use poly. I end-up using epoxy just to make sure the bond was strong with the hull (where it failed in the first place), and figured it would be stronger than poly on poly.
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Old 06-03-2013, 11:51   #385
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Re: Nauticat 52 Refit

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I did the same... looked great in the bright sun, but then the sun starting setting. Found out that I made it way too creamy of a color and it looks horrible now. Easy enough to grind out and try again.

Question about polyester vs Epoxy. Isn't the reason to use epoxy on a poly boat for the secondary bond that epoxy has? I had to repair some tabbing on our boat, and the local fiberglass guy wanted to use poly. I end-up using epoxy just to make sure the bond was strong with the hull (where it failed in the first place), and figured it would be stronger than poly on poly.
This is what I always thought too because, either way, you're dealing with a mechanical bond vs. the original chemical bond which was much stronger. I think the problem is getting the final layer of gelcoat to adhere to whatever you've used to do the repair, whether it is epoxy or marine-tex. By using poly, I guess you're more in sync with the chemical makeup of your underlying materials, thereby improving your chances of getting proper adhesion.

I'm sure Minaret will tell us if I'm right or wrong!
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Old 06-03-2013, 13:14   #386
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Re: Nauticat 52 Refit

Polyester gelcoat on an epoxy laminate:

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Old 06-03-2013, 15:32   #387
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Re: Nauticat 52 Refit

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Is there usually then a cause & effect, i.e. some nearby deck fitting that perhaps needs a larger backing plate, for e.g.? Once remedied, would you want to lay down new laminate or just one of the fillers you mentioned previously?

Sometimes. More often its a stress riser caused by the geometry of the part. Also I see a whole lot of fasteners that have been tapped into a fiberglass deck and then over torqued. This results in fractures. Sometimes they don't appear till much later. One of the reasons I don't like tapping into glass. New laminate is the way to go.

A small repair like a fastener hole might look like this after being Roloc ground, glassed a bit high, ground fair, coated with primer gelcoat, and sanded for prep. In this case it's prep for paint so it's a bit misleading.
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Old 06-03-2013, 15:43   #388
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Re: Nauticat 52 Refit

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Oops, it sounds like someone wanted to save a few bucks on primer? Interestingly, West has some lengthy treatises & even testing that says gel over epoxy is OK, but then both 3M & Evercoat specifically warn against.


You will find there is much debate on this. I can only report my personal experience, which has not been good. I tend to play it safe anyway, I hate going backwards.

What about the gel paste they give you in those overpriced little "gelcoat repair kits"? Is the paste a faster but still appropriate way to build up the gel?

Never, ever purchase a gelcoat repair kit. That stuff is for suckers. Don't buy gelcoat from West Marine either. Don't use gelcoat that came with a boat. Use only fresh gelcoat from a reputable fiberglass supplier. Shelf life of gelcoat is around one year, almost all of the aforementioned sources will be older than this. I believe this is the source of much of the myth of gelcoat curing problems and color changes.



OK, here's a couple more DIY projects this thread has inspired me to put on my list. I'm only asking, mind you, because others apparently have not yet come to appreciate their obligation to prevent you from getting bored at work:

G10 for backing plates: I'm mainly thinking lifeline stanchions here, but also potential for swim ladder fittings, etc. No corrosion, strong as hell. If a good choice, then how thick to buy the sheets & is the stuff reasonable (for a DIY'er) to cut & drill.

Very common these days. I wouldn't use anything else, unless its homemade flat stock. It's very easy to make your own flat stock table and crank out your own fiberglass plate stock for dramatically less than G10, though it won't be quite as ridiculously strong for a given thickness. Still overkill.




"Flex-Mold" for molded-in non-skid: My instinct sees potential for disaster for anyone other than a pro using these, but I don't know how else to restore my non-skid gelcoat, unless it's feasible to use the grit that's commonly used with paint. Personally, I think the molded gel looks a lot better than any paint I've seen, but mine is getting slippery. In fact, I'm afraid to put anything on it at this point (e.g. compound or wax) for fear of making things worse.

I've had to use a lot of Flex Mold and I hate it. It doesn't work, at least not well enough for me. I have another method which I have already detailed on other threads. Might work for you.
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Old 06-03-2013, 15:53   #389
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Re: Nauticat 52 Refit

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I know, but all the Sundeers have it. My surveyor told me the gelcoat was incompatible with the vinylester layup. I just think they used low quality gelcoat. Anyway, like you write, only grinding will tell for sure.

So, after grinding, I assume wet out with resin and use cloth to build up? I think you use gelcoat for finishing? I hear that many use MarineTex, what is your idea about that? I used it once, matched color with the same pigments as for gelcoat and it worked much the same as gelcoat. May be it is no so brittle, I don't know. I do know my color matching sux


I never use Marine Tex, don't like it. Glass with a layer or two of boat cloth in the bottom of the repair and then glass a little high with two or three matts. Then grind fair. If you triple tape tight around it before you glass, and your glass comes onto the tape a hair, you know you are close to fair around the edges when your grinder hits the tape. Then you go to a little teeny hard block with some 36 or 60 grit on it and scrub it out until you are almost blowing through the tape everywhere. The you pull the tape and retape further back, and block it again with 80. Then prep sand the halo and brush on three coats of primer gel, making sure to cover all the 80 grit and coarser scratches with primer so when you sand primer the whole repair will be in finer grits with no deep scratches left. This gives you a nice repair with no bondo, and it's easy and quick.
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Old 06-03-2013, 16:03   #390
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Re: Nauticat 52 Refit

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I did the same... looked great in the bright sun, but then the sun starting setting. Found out that I made it way too creamy of a color and it looks horrible now. Easy enough to grind out and try again.

Question about polyester vs Epoxy. Isn't the reason to use epoxy on a poly boat for the secondary bond that epoxy has? I had to repair some tabbing on our boat, and the local fiberglass guy wanted to use poly. I end-up using epoxy just to make sure the bond was strong with the hull (where it failed in the first place), and figured it would be stronger than poly on poly.

That would be the reason all the epoxy fanatics give. The fact is that most of the structure of a boat built in the factory relies on secondary bonds too. It's not like they can build the whole boat all in one day! All the stringers, frames and floors, and bulkhead tabbing rely on mechanical bonds. Poly does just fine in this regard with good prep work, I don't ever get warranty work back on repairs. And it's a ten year warranty. Don't get me wrong, I love epoxy and it certainly has a place. But there are much faster more affordable methods that are more than sufficient in many cases.
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