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Hull fixing tips/advice

Mashmaster

Active Member
OK, the hulls that we got for free with the holes in it and ready for repair. Looking for last minute advise on fixing the hulls. I have epoxy, bi-axial fiber cloth, fiber mat, peel ply, fairing compound, marine-tex, and gel coat.

For the two "holes", I saw the tip to insert a piece of cardboard with a layer of fiber mat folded, inserted, and pulled against the inside of the hull by string. I think I only need to do this for the one big hole.

For the others it looks like the steps are clean area with acetone, cut and place layers of epoxy infused fiber mat pieces from small size to increasing sizes until almost hull surface level. sand area flat, hand paint area with gel coat, let cure. hand sand the gel coat and surrounding area.

For the non-hole areas, just cover area with gel coat by brush?

Do those steps sound correct? Would you use any fairing compound?

For the deep scratches, would you just clean with acetone and then paint on gel coat over the scratch?
 

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signal charlie

Well-Known Member
Staff member
You probably won't need fairing compound if gelcoat does about the same, but if you do, make sure it is compatible with the gelcoat.
 

beldar boathead

Well-Known Member
cut and place layers of epoxy infused fiber mat pieces from small size to increasing sizes...

isn’t it supposed to be the other way around? I think you want biggest pieces with max surface area directly over the hole.
 

Webfoot1

Active Member
You need fiberglass filler. The smoother and more finished
the surface the less hassle getting a professional looking gel coat.
Gel Coat is non leveling so you'll still need to do some final work
but it will be much less.
 

Mashmaster

Active Member
OK, during the lockdown my son and I have been busy working on fixing my laser and my son's Sunfish. Remember the huge holes in the hull pictured above. They are patched now. Yes, we have a lot of sanding left to do, and I used too much epoxy. As it cured overnight I got drips I wasn't expecting. But I the holes are patched and solid. After sanding, I will proceed to gel coat. Time to learn yet another skill.....
 

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signal charlie

Well-Known Member
Staff member
Looks good. Be careful sanding the edge of that chine, it is easy to go too deep and you end up chasing a fair curve.
 

Mashmaster

Active Member
Thanks, the shape came out pretty close. When I put the fiberglass down, I covered it with wax paper and was able to match the profile well. Light sanding over the patch, more sanding out the excess epoxy drips..... doh.
 

Cactus Cowboy

Well-Known Member
At least you're filling those holes with some solid material... further sanding will indeed be necessary, but like SC said, don't spend too much time on that hard chine, you don't want to take that down too much. A razor knife & rasp will help remove some of those drips and excess resin... otherwise use your sander and various paper grits. Henceforth, I wouldn't bother with tape or wax paper, just let any final coats of resin cure in open air. :rolleyes:

Dunno if you're using a glass repair kit, with only so much catalyst included? According to the instructions for some of those kits, only a minimal amount of catalyst is recommended, to ensure sufficient 'working life' for each mixed pot of resin & catalyst... flip side of that equation is that the resin takes FOREVER to cure, and it is more likely to run or drip as seen in your pics. :confused:

A little extra catalyst speeds up the curing process, but you don't want a 'hot pot' either, which cooks off too soon and becomes worthless. At the surf shop, with heaps of boards to repair, my friend Tommy had it down to a science, mixing only what he needed and often juggling three repair projects at a time. He'd buy his resin by the 55-gallon drum, and catalyst by the quart or whatever... so he knew a little about glasswork, LOL. ;)

Moi, I was always better at boat repair, that was more my specialty... but what I'm really trying to say is that there's a tendency for folks to mix MORE resin & catalyst than they need for any given project, and then, since they already mixed it (and PAID for it), they use the ENTIRE POT, which leads to excess resin and drips, aye? With experience, one learns to mix only what is needed... saving money in the process. :D

I used to like adding an extra drop or two of catalyst to my resin pots, which were paper cups, small recycled yogurt containers, whatever I needed to mix only as much resin & catalyst as that particular step in the repair process required. I'd stand by with a rag and a little acetone to wipe away any runs or drips, having a beer while I waited for the repair work to set. Not a bad program... just leave the actual repair alone, it can be sanded later once the resin has cured. :)

Once you sand those repaired areas, look for any partial air bubbles or exposed glass fibers at the surface, those should be filled or coated with more resin. I suppose you're going to paint that hull afterward? That'll go far in hiding all repair work. Just be sure to sufficiently sand down those repaired areas so they match the hull around 'em, no telltale lines or raised glass to show through primer & paint. My $.02, FWIW... CHEERS!!! :cool:

Edit: Oh, I went back and read one of your previous posts and you want to use gelcoat instead of paint... meh, as adults we all make choices, LOL. :rolleyes:
 
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Mashmaster

Active Member
So you wouldn't use wax paper? I like how I can use it to help smooth out the repair and match the profile. It probably is also why I got the drips.... I have the epoxy in the matching pumps and a huge roll of fiberglass, so not a repair kit. So it sounds like I could give an extra half pump to the hardener to make it gel faster. I'll try the razor otherwise sanding will be happening :) will be happening anyway.

I tried not to use too much but I wanted to make sure it was fully saturated the cloth as well. It was my first every fiberglass fix, so I am learning. Makes sense about the acetone and beer, don't mix up the two....

Is gelcoat really that much harder to do than paint? I already have it so that is my plan to use. Fromt he directions, it looks like you mix it, paint it on then sand. I don't have a sprayer system available to me.
 

Cactus Cowboy

Well-Known Member
Um... you're using epoxy RESIN & not epoxy GLUE, right? Somehow I pictured separate resin & catalyst containers. Polyester resin would be fine for this sort of repair, and it's usually a bit cheaper. Fully wetting the surface (and wetting up the cloth or matt after it's laid) is a good thing, less likelihood of air bubbles that way. I usually use a throwaway brush for this sort of wet work, with a small rubber squeegee at hand if I need it. As for the gelcoat, it's always tougher to color match, but in the past I usually wanted to repaint anyway, so I'm biased, LOL. Some libtard may call me out on this bias, but that's to be expected, don'tcha know? Hey, I'm back to my skirting repair, I want to knock out a certain amount of that skirting today... we have hot temps in the near future (again) and I don't wanna be messing with the skirting when it's hot outside, even though I'm under a wide full-length metal awning on the west side of my home (wide concrete slab beneath the awning, same as the east side). I'm also having a quick Tecate cerveza with lime to boost morale... no acetone required, LOL. :eek:
 

Mashmaster

Active Member
Yes, resin. Hey, I am a newbie at this :)

Your steps are how I did it, except I pumped one pump of resin into the mixing container and then one pump of catalyst. stirred and applied to the area, laid the fabric pieces down, applied until translucent, then covered with wax paper and smoothed the patch area.

Enjoy the beer :)
 

Eddie_E

Active Member
Make sure you really scrub the epoxy patch well with acetone before rolling out the gel coat. Getting a good bond over epoxy can be tough because it develops amine blush when curing. I personally only use polyester resins for repairs when I plan to gel coat. The easiest way to lay down gel coat for the first time is to use a tight grained white foam roller. They come in a 4"wide version with a rounded tip that doesn't leave a hard line. You need a roller without the basket for them. Epoxy works well for chips and deep scratches with a little resin tint added though.
 

Mashmaster

Active Member
Make sure you really scrub the epoxy patch well with acetone before rolling out the gel coat. Getting a good bond over epoxy can be tough because it develops amine blush when curing. I personally only use polyester resins for repairs when I plan to gel coat. The easiest way to lay down gel coat for the first time is to use a tight grained white foam roller. They come in a 4"wide version with a rounded tip that doesn't leave a hard line. You need a roller without the basket for them. Epoxy works well for chips and deep scratches with a little resin tint added though.
Thanks!
 

Whitecap

Active Member
For bigger holes than normal (especially ones that are on a curved surface like you are dealing with) I found the “Shoreline method” to be really effective and easy to do.

(For future reference the next time you bang up your Sunfish - as me and the kiddos have!)


 

kbanjo

New Member
Looks like you sprayed it with just an hvlp? How did that go? Did you rough up the old gel coat to give it something to bite on or remove the old all together?
 

Mashmaster

Active Member
Looks like you sprayed it with just an hvlp? How did that go? Did you rough up the old gel coat to give it something to bite on or remove the old all together?
My son marine tex'ed any scrapes and grooves, then sanded the entire hull with a body profile sander at a 220 grit, wiped it with acetone. My friend sprayed it with an HVLP sprayer with 3M disposable tips and bags. Thinned the gel coat with acetone. Two coats were sprayed then a coat of PVA.

We still need to pick up the boat to sand off the PVA and buff out the gel coat.
 

Woodwind

Active Member
About amine blushes...

somewhere in this post it was recommended to use acetone to remove an amine blush

There’s something you should be careful of when working with epoxy.
Acetone will not remove an amine blush when using two part epoxy like West System And others.

It’s water .....or better, warm soapy water and a Scotch-Brite pad that removes an amine blush.
An amine blush is water soluble.

If you do your epoxy work in a dry enclosed garage the blush does not always occur.
Humidity affects whether or not it occurs.
If it does you can look closely and you can scratch it with your finger nail, it’s almost a waxy like substance.

But to play it safe, for all epoxy work I always Scotch-Brite the area with warm soapy water and RINSE very well.
this way the amine blush will not get sanded into the area and contaminate the surface and interfere with the adhesion of the next part of the process either fillers or paint.

When you wash using a green Scotch-Brite pad and remove the Amine blush you can see it accumulate in the pad.
it’s an opaque whiteish waxy substance.

I prepped a full keel hull for a professional to follow with a dyneema cloth sheathing of the hull.
I was working outside in the humidity on a 30 ft Herreschoff design....closely instructed by the pro on how to look for and remove the amine blush....
this was a big job below the waterline I did not want to repeat due to adhesion issues.:eek:
so I was very careful. But the amine blush is easy to see and remove without much elbow grease really once you understand what it looks like.

No worries, the Sunfish is smaller job, but still in areas that you repair with epoxy, you want to make sure you understand how this works.

When beginning to work with resins it is good for you understand the difference between polyester and epoxy resin.
Remember, you have to know which one sticks to the other.
Epoxy adheres well to polyester, but polyester repairs over epoxy are not recommended.

West system has all the information online and they also have brief instruction pamphlets that are generally free if you’re not dealing with a marine supply scalawag that charges for them.

Scotch-Brite pads can be found at all Automotive paint supply houses and sometimes at the discount auto parts stores.
The pads you have in your kitchen attached to the sponge are not quite the same they don’t hold up to this, too soft...and they can leave a little green particles behind that get incorporated in your topcoat.

Cheers! to sailing ...and learning
 
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Mashmaster

Active Member
Marshmaster, this hull Turned out beautifully, nice job!
Thanks, my son did the bulk of the work. He doesn't want to put it in the water it looks so nice.

There is one little dine size spot near the back that you can see the marine tex from when he finished. I know it is fine, but would it be a mistake to paint on gel coat just over that spot or will it not work well?
 
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