Brutal sanding job!

Raka is a bit thin for this application and not the cheapest. Check with Bateau.com for their Marinepoxy or with EpoxyProducts.com for more economical and slightly more viscous formulations, that haven't any filler in them. You can make a very effective barrier coat yourself, without the cost of a paint manufacture's rebadged and marked up product.

Agreed with the rest of the comments, if the existing coating looks solid and sound, just fill the divots and prep for paint.

 

A safe way would be to grind everything fairly smooth and then laminate with 8-10oz cloth and epoxy. That way, if there are some fibers that got damaged, there will be some structural integrity added. Also, it will only need one coat.

 

So called barrier coats such as interprotect are really just a primer and not really a barrier at all, they are easier to apply as they are less viscous than 100% solids such as Raka etc. They require a lot of coats because they have solvents in them which evaporate away leaving pinholes, but by the time you have 5 coats on this is not a problem. In fact in a situation such as yours where the fibers have been compromised international paints require you to seal the raw glass with 100% solids epoxy before applying the interprotect, in their case they will try to sell you Epiglass because it is one of the companies owned by their parent company but any of the cheaper alternatives as suggested by Par will work as well. So really the barrier is the epoxy resin and the interprotect is the primer and its actually a pretty nice one. You can just use 2 or 3 coats of epoxy then straight to bottom paint or use a couple of coats of interprotect as a primer over the epoxy or you can pigment the epoxy so its a solid color instead of clear.I think the Gougeons have you add aluminum powder to the epoxy, not sure why. You do need to develop a technique for applying epoxy as it is not a paint and can run pretty easily, as with most coatings multiple thin coats wet on wet works better than trying to put it on too thick. The Gougeons have good instructions on how to do it.

Steve.

 

1 coat resin then Interprotect2000e. Fill over resin. Apply Interprotect on sanded filler. I think the spec is 5 coats over the resin/filler.

If you go multiple coats resin you have to watch a) temp and humidity b) overcoat times...ie you have to apply wet on tacky or you are sanding between coats.

If you use Interprotect 2000E you get extended overcoat times without sanding. It will also cure at cooler temps and higher humidity without problems. You can apply multiple coats in a day or just do a coat a month.

The ease of use is better. Mix and roll. Long working time. Resins are thin as water...but sticky if you know what I mean, roll like runny crap. You will want to apply more than it can take. Until you learn. At which point you will only be applying marginally more than a coat paint per dry coat.

I just think the ease of use of the paint beats the cost savings...if there are any. And at the end of the day I will guarantee the paint job will look smoother...although this is of moot benefit in this hull.

"Not barrier coat" said someone. Interesting comment- False comment.

Paint a piece of steel with 250microns resin and another piece of steel with 250microns Interprotect. Hang both in sea for >6 months. remove the rusty, possibly completely peeled off film of resin. Admire the Interprotect panel, clean as day it went in.

Interprotect will beat 2x thickness of resin (any sort of room temp cure resin) in any sort of measured barrier property easily.

If unpigmented resin was so great a barrier coat it would be used to coat steel.

ps I know it is more complicated than this but less dodgey claims please. It doesn't help those in need of info. Otherwise your advice was fair Steve

 

Great information from everyone. I've picked many brains over this one. I will:

1. Properly sand the hull around the exposed fiberglass areas.
2. Fill and fair the gouges with epoxy
3. Add a few coats of epoxy resin over everything
4. Add 10 mil (0.010inches) of InterProtect 2000E
5. Antifouling

Thanks again everyone.

 

Good analysis - the only improvement to the job list (I can think of is )

2. Cover the gouges with epoxy
2a. Fill the gouges with thickened epoxy ( light filler with some talc or microballoons and cabosil ) to help with sanding) - before the initial coat has gone hard.
2b. Fair the hull.




Ps 10 mil doesnt equal (0.010inches)

.01 inch = .25 mm
10 mm = .39 inches

You dont want or need 1 centimetre ( 10mm ) of epoxy all over the hull.

 

Good call, never was good in math.

 

Don't get too excited, the good citizens of the USA still haven't managed to get out of the 19th Century when it comes to measurement units.

There's some ******* sort of measurement called a mil which seems, sometimes, occasionally, to some people, to equate to one thousandth of an inch (0.001") which is actually a THOUSANDTH of an inch not a MILLIONTH so why it's called a mil is beyond me but there's probably a reason that makes sense.... in the 18th Century.

However it has nothing to do with the SI unit of measurement known as a millimeter so don't get confused.......

PDW

 

The way I figure it, the world has yet to catch up with us. It funny how quickly other nations cry about the ills of the USA way of doing things, but frankly we've gotten it done, without peer for a long time. I don't see any other nation or group of common measurement system organizations, getting together and putting men on the moon. We did, using slide rules over a half a century ago. Maybe in another half a century of so you'll catch up? I also don't see the level of innovation and work ethic that I see in this country, anywhere else. We work hard and play hard, but we also, in spite of our "inferior" measurement system, have attained much, invented much and continue to push the envelop is every regard. While some nations have begun to play with stealth fighter technology, we've been at it since the 60's.

All this said, in most every way, the USA is metric. With the exception of old farts, that can't give up what they learned in grade school 3/4's of a century previous, to lounging around on line discussion forums. With the exception of very few items, everything in the USA is metric. Now, will someone call the tire rim and mag wheel manufactures and have a long talk with them about rim diameters, though I do have to admit buying a set of 55.88's just doesn't have the same ring as a set of 22's, but maybe I'm just an old fart.

 

It is frustrating that we will not make the switch to metrics, it insane really, i cant think of any reason other than ego why we don't do it, as par said much of industry uses metrics, they have to. The funny thing is everyone has been using metrics their whole life but dont realize it, yes weve always had metric currency, if you can make change your halfway there.

Steve.

 

Colin, I agree, as a rust preventative coating on steel interprotect works better than 100% solids epoxy, however the OP dosnt have a steel boat, he has a fiberglass boat that has been ground through to raw glass in places, FOR THIS APPLICATION the makers of interprotect require you to first seal the raw glass with epiglass, a 100% solids laminating epoxy resin before applying the interprotect, in other words on its own it is not an effective moisture barrier on raw glass, particularly csm. When it is used on a properly prepared, undamaged gelcoat bottom at the required dry film thickness its fine but then so would be many other 2 part epoxy primers.

Steve.

 

Well put Steve. Sounds like plan. Also, you were right regarding the VE skin vs. the epoxy (the builder tells me now that he didn't use epoxy for the first layer. It was either Vinylester or a good quality poly resin (he has to look into it, I think there have been changes over the years).

With that in mind, will epoxy resin (epiglass) stick to vinylester...if that's what this outer hull could be?

 

Yes, no problem with epoxies adhering to either a VE or PE. Some builders have used VE for the skin coat next to the gelcoat and then PE for subsequent layers. You don't need to use epiglass although it is as good as any, there are many cheaper alternatives.

Steve.

 

Good to hear. I have a pretty good port supply discount with West Marine, so it's probably cheaper for me to use West System for those 2-3 layers of solid epoxy, followed by 5 coats of the InterProtect. Thanks for your help again Steve.

Chris

 

I'm thinking West Marine and West System are two very different entities.