Epoxy (floor) paint for a boat?

I see, thank you for the explanation. I asked because I saw some opinions that epoxy, even with UV resistance additives, will still discolor and degrade in the sun, and that you absolutely must use a different kind of paint on top. Not sure how much truth there is to it.

As for pouring method you used, it does seem like a very nice way to achieve a level surface, but in my case the boat is very curvy, there isn't a single flat surface anywhere, and the radiuses are large, so I guess rolling is my only option. Do you think that graphite powder would work with 2K PU paint, should I use it? How much did you add? As I understand it inevitably tints the paint black, making it impossible to preserve the original color, correct?

 

There is no point in my opinion of painting over an epoxy surface that has had additives added. Paint will not stick to an epoxy graphite surface, but i have seen coppercoat abraded and over painted with anti-fouling/bottom paint. If i recall, 10% by weight for the graphite. With copper powder you want as much in the resin but can still apply, so it depends on the viscosity of the resin you use which maybe 20%+.

Being under the boat, these finishes do not get much sun exposure. I have not read of anyone having issues with UV damage. Sun UV will break down everything eventually. Topsides, pigmented, oil based, 2 pack PU or epoxy will all chalk eventually.
All topside paint on the superyachts that came out of the yard i worked at was 2 pack PU, hard wearing and shiny, but not often dragged across beaches.





That will not buff out.

 

I see, so in order to make this work, I would have to add graphite to a large enough batch of epoxy, and then keep adding pigments to get the color I need (navy blue). Not sure if that is possible, but perhaps I can test it out. Thank you for your suggestions, this is very valuable info. And funny pic

 

Rather than graphite, you might try aluminium powder. I believe in the West bible, paint tint up to 10% is ok. I have heard even oil based works, but i would not commit without a test first, or confirmation.

 

Any reason you cant just put a few UHDMW chopping boards under your hull before dragging it?

 

This is how our typical regatta venue looks like.



Shore packed with boats like sardines in a can, semi-immersed in water, with sand or gravel underneath. Sometimes it gets much worse (second line of boats parked on the sand behind the ones in the water). You are lucky if you get a grass patch, most of the time you don't. Sometimes you have to park your boat between big rocks, jamming it tight enough so that the waves don't bang it around too much.

There are always more boats than there are free spaces, so no one has a permanent spot, every time you come to the shore you hunt for a spot, or wait on the water until one frees up, missing your lunch break. Wind constantly moves the boats around because people can't be bothered to lower their sails down (or they can't be lowered), which means boats constantly bang into each other. From time to time someone's sheet gets tangled, and their boat falls onto other boats, steel hardware banging, scratching and gouging them. I once had a neighbor boat fall on me, and their mast spreader took a big chunk out of my gunwale.

If you have a trolley, the only time you can use it is at the beginning and ending of the regatta, once enough boats clear the shore so you can drive it in. Definitely NOT every time when you want to launch from shore or return, trolleys are typically parked somewhere far away from the shore to maximize space for the boats.

It is total chaos. I did try to bring a carpet with me to several regattas, thinking I could place it on the shoreline to park my boat on it. Waves carried it away. Then I put some rocks on it to hold it in place. Some guy kicked the carpet with his trolley when he drove past. Then finally a big boat blocked that spot and I couldn't get to it anyway. Same with the chopping boards idea. It's just unrealistic to create any safe spot for your boat and expect it free, unobstructed or otherwise undamaged when you come into the shore. And that would be one extra thing to carry to every regatta. Even the carpet was really impractical.

In our conditions, what you want is a boat that needs no trailer, no trolley, maybe some transom wheels, tough enough to survive all that abuse, and still retain slick enough bottom to go fast. Conflicting requirements, I know, but that's the reality of the regattas where I live

 

Ok, its good to get an insight as to your needs. Transom dolly wheel is a good thing to have anyway, i had one for my sail canoe. Sounds like a slick/hard bottom paint wont help you much with others who are happy to wedge themselves between boats. I would perhaps be thinking of a string of pool noodles for the bottom and around the deck........or just face facts that re-coating paint will be a regular occurrence.

 

Coppercoat is intended as an antifouling surface.It wouldn't be my choice for a racing dinghy in any circumstances.Any 2 part polyurethane will need to be applied by a sprayer wearing lung,eye and skin protection.If you can find brushable paint it will most probably have brush marks in it to some extent.Neither cars nor boats are expected to have a high quality finish dragged through gravel and if you treat it this way,there will be damage,even if it isn't easily visible.Don't apply a gelcoat to a finished epoxy surface unless you have done a sample piece and given it an equivalent test to the treatment it will receive in use.The general rule is that you can apply epoxy over polyester and not really do it the other way round.For this exercise polyester and vinylester are equivalent.With the pressure on launching space it might be a good idea to gather the sailors for a weekend of creating some room and maybe a parking area for trolleys.

 

Well yeah, I could pad the boat with noodles, foam and whatnot, make it as rugged as a Michelin man, but I doubt it would do that well on the water So what I learned from attending dozens of these regattas is that the boats with hardest hulls/surfaces tend to do best on the course (since they have least scratches that add drag), and also require least repairs because they are more durable than the other boats that rub/crash against them, or the surface on which they have to be dragged. I was hoping that it would be possible to achieve similar hardness with epoxy paint (or just pigmented epoxy with graphite like you suggested), but as I understand it still won't be as durable as these molded gelcoat hulls. In my experience, epoxy (at least the ones I used) aren't that scratch resistant either, even when fully cured... Perhaps graphite does make a difference, but then it becomes the issue of whether I can pigment that epoxy+graphite combo well and repeatably enough to get the hull colors I want. I plan white for the topdeck and navy blue for the bottom. Probably need to do some experiments and see what I get. Or just forget it, go with 2K polyurethane and live with the scratches.

Thanks for the advice. As for creating room, we have more than a dozen different regatta venues all over the country, each one used once per season, and it is the same situation in every single one of them. There were some talks of try and expanding at least a few venues... But I don't see it happening anytime soon, since most people here have factory boats with gelcoat hulls and don't get as much scratching as painted DIY boats like mine.

 

Epoxy paint and floor coatings are different than normal epoxy resin, they have solvents, pigments, and other ingredients that make them a better paint, but are less durable than straight epoxy resin.

Epoxy is more durable than gel coat and is an option for a tougher finish, but when you add good to great cosmetics to the mix it compromises the chemistry. Graphite powder is supposed to help, but again, cosmetics are sacrificed, I haven't done any direct comparisons though.

Brushing and/or rolling epoxy won't give you a great finish, so sanding will be required, and because it's a tougher finish it will be more difficult to sand.

What are the other people using on their hulls?

 

Thanks, this is valuable info. In my experience epoxy additives and specific formulations for viscosity do indeed matter a lot. For example, no matter how much I played around with various combinations of fillers to make epoxy putty, it is still nowhere as good enough as commercial epoxy fairing compounds like TotalFair. I suppose it is the same with paint.

Well as I understand it, nothing, it's just how these boats come out of the factory after molding - gelcoat finish with no additional paint. I only met one guy in these regattas who said he had to do scratch repairs on that kind of a hull, after he ran aground onto a rusted steel structure at high speed. He used some more gelcoat and lots of sanding.

 

On my dinghy that i did the pour and spread and brush, that was an undercoat of clear epoxy, to fill the pores, seal the surface, and harden the outside of the hull, then drips and runs were filed / sanded, some filler used where needed, and the hull roughly lightly sanded with new 60 or 40 grit, to scour the glossy surface, then painted with several coats of glossy outdoor enamel paint. It holds up to almost anything, except razor fish shells, which act like a hard scraper, taking the paint down to the epoxy. Don't bother even trying water based acrylic paint, it isn't tough at all.
Paint your epoxy with outdoor paint for UV protection, or even marine varnish layers helps protect the epoxy, and still allows the substrate colours and patterns to come through. My unprotected epoxy is disintegrating after 2 years of low wear use; the painted epoxy still perfect condition, as far as UV goes.
You could get some stainless steel angle and strip, (0.6mm is thick enough), and use it to 'harden' the bow, centreline, keel, and chines, where most wear occurs on a dinghy, screwed in with countersunk varnished screws. Even gunnels could be 'armored', if it helps.

 

The pool noodle suggestion was to just have them threaded onto to lines you can wrap under the hull and topside edge and just tie off. It would keep the bottom off and your neighbours edge away. Three 2m lengths would help, just leave them ashore when not racing. Sounds like your issue has as much to do with the people you sail with along with ground conditions, you cant do much about the latter.

 

Maybe not a bad idea. If I were to find a quick way to wrap them around the hull when landing and recover when launching (typically you have to do it very fast because there's 10 boats ahead you doing the same and 10 behind you waiting for you to get out of the way), then it could work. As for people and conditions, yeah, I kind of agree, but the biggest issue is that our venues are extremely small, beaches can't be expanded due to them being under nature protection laws, and there are A LOT of boats. There' just not enough space. Add inexperience and gusty winds into the mix, and collisions become the norm. Think of Demolishion Derby, and you'll get the idea No one wants it to be that way, but trying to protect your boat there is like trying to get onto a subway train in Tokyo and expecting not to get your neatly ironed shirt messed up to hell. But anyway, I will probably try what you suggested.

Also good idea. I will experiment with these chemicals and see if I can get a decent result before I commit to anything.

 

There used to be a source of black plastic D section keel bands which were about 12mm wide and 4mm deep and which could be attached with contact glue.It does save quit a lot of scratching but seems harder to find than I expected.If the risk of damage is severe,it is quit reasonable to add an additional strip at the point where the boat would naturally sit on it's bilge.