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coating with epoxy

5K views 26 replies 9 participants last post by  Barquito 
#1 ·
I've been building a little dinghy for some time and sadly no matter how slow I try to go it seems to be getting closer and closer to my having to finish it.

This is a stitch and glue design with marine ply. It is designed to be encapsulated with epoxy then painted except for the bright-work trim.

The plans and west system directions call for several coats of epoxy.

The problem I'm having is that you are not supposed to thin epoxy but it always seems so rough.
I put it on with a west system roller and tip it out to get it as smooth as possible but by the time I sand it so it is smooth it seems as if I sanded most of it off.
I'm thinking I will just do three or four coats without sanding to build up some depth before sanding. Since I'm doing this an hour or so at at time I can't time these west system coats to wait for it to get tacky before the blush.
So I'm thinking of switching over to system 3 epoxy which does not blush and just do a pot every night until I get three or four coats then sand it smooth which will take off the last coat for sure.

Does this sound like a plausible plan?
I have to switch to system 3 epoxy anyway as it is required as a base for the system 3 LPU paint I'm planning on using.

I'm planning on using the system 3 LPU paint which is a two part water based paint which I'm told will not smell too bad because I'm working in the basement and don't want to stink up the house.
 
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#6 ·
change your west system hardener. 207 hardener doesn't blush. It also lays better, needing less sanding and better coverage.
I'll check that thanks.

I noticed that guy with a squeegy finished up with a roller.
 
#5 ·
you don't need to put that many coats of west on. all you do with it is seal the wood then you go to a primer and paint system to get a smooth colored surface. the bright work is done by coating the west system with coats of clear uv varnish which gives the smooth shiny surface and protects the west from the UV.
 
#7 ·
David, 207 hardener also has UV blockers. Any 2 part urethane paint will bond to epoxy by the way. Some one part paints won't dry 100% and stay tacky forever, so you will want to test the paint first.
 
#8 ·
Some one part paints won't dry 100% and stay tacky forever, so you will want to test the paint first.
???????????????????????? Can you elaborate?
 
#9 ·
A bit involved but maybe worth trying.
You are trying to build up a smooth epoxy layer. What if the epoxy hardened in an absolutely smooth surface that required little or no sanding?
I've had some luck with this method on smaller repairs.
Get a mold release agent McLube : Mold Release and some panels of plexiglass that will fit over the flat sections you are coating. Lay the epoxy on as evenly as possible then spray the mold release on one side of the plexi and lay the plexi down on the epoxy. Use some weights if you have to so the plexi sits flat and comfortably while covering the epoxy. Once the epoxy hardens you should be able to remove the plexi (hopefully in one piece) leaving a smooth surface that needs little or no sanding.
This technique works pretty well with Bondo as well.
Other plastic panels should also work for making mold shapes. I've used thin plywood (1/16") so it could be bent to match the shape of a hull but it is hard to get all the ply off the epoxy once hardened which leaves you with some sanding to do.
YMMV
 
#14 ·
David .. Really cool .. I used to build little 7 ft prams for fly fishing out of door skins and 1/2 inch cedar ribs and transom ... Just need enough epoxy to get good seal, then I used good marine varnish ... they look so great and weigh nothing wish I still had pics
 
#15 ·
david, I have been contemplating building one of those... a lot. In fact, everytime I retire to the porcelain library and open a dog-eared copy of Small Boats, it magically seems to fall open to this page.

On a barely related note,this just came up for sale locally:


Shellback dinghy - City of Toronto Sailboats For Sale - Kijiji City of Toronto Canada.

I've already built a small dinghy. I am building a 25' cruising catamaran. I have just started building a 9' catamaran dinghy. I don't NEED another small boat, especially one that is too long and too narrow to be a good tender, and I definitely don't have room for another small boat and I prefer building them to buying them...
....but damn it's tempting. Small boats are an addiction.
 
#18 ·
David, I really like the spindrift designs!

My son moved away so The canoe and boat building came to an end about 5 yrs ago. After a couple of plywood kayaks, 5 or 6 strip canoes and a few other boat projects I was in love, every morning I'd spray varnish behind my ears! (kidding of course) shellfish with cedar flavor from the steam box is missed also! After the ribs were all bent over the form.

Atkins vintage Photos of Vintage
I want to build someday. Just love lapstrake boats.
 
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#22 ·
I'm okay with decent quality luan underlay/door skin.
The key word in the above sentence is quality. It is out there, but you do have to look for it. If you're going to seal it with epoxy anyway, then waterproof glue isn't a deal breaker to me, and i like knowing I can go pick up more from the local lumberyard less than 5 minutes away.
 
#27 ·
I think some run a hair dryer over the wet epoxy to get it to smooth some. O/W, unless you don't care about weight, should only be a few layers. Wet-out raw wood, glass, then maybe one more layer. If there are any imperfections fair those spots with thickened epoxy b/f painting. I'm going to be driving a couple hundred miles next weekend to get some marine ply to start my project.
 
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