Barrier coat or Epoxy for coating bare wood hull

[ajay73]

I'm going to build a lapstrake sailing dinghy. The dinghy will never be moored or docked in the water. Just taken to the water each time I use it. Stored indoors in the off season and in season when not in use. I should use epoxy to seal the inside and bottom but I have become sensitized to epoxy when I use it to coat surfaces. I would rather use an epoxy barrier coat (like 2000E) if it would be considered sufficient to protect the wood when the boat is being sailed. I have used 2000E barrier coat and I don't get a skin reaction when I've used it. The hull is being built with meranti hydro-tek BS1088. Lap joints will be epoxied with Six-10 west system thickened epoxy. Would the barrier coat (5 to 6 coats) be sufficient to protect the wood hull? Would using a layer of glass cloth set in a vinyl ester resin work too? I can use poly ester and vinyl ester resins without any allergic reaction.

[Spot]

On my plywood dinghy, the combination of plywood and epoxy resin used as a 'paint' failed where there was not fiberglass cloth after a couple years out in the weather. Sort of a chain reaction I think: wood moved, cracked epoxy, allowed in water, more movement, more cracking...I had glassed the bottom and that did well except for a few pinholes. Not looking forward to the rework but also do not want to have to discard a boat that is only a few years old. I have seen similar issues on timber and epoxy only finishes too, not as bad as plywood but the glass cloth really does help.

In regards to epoxy allergy, why not do the lap joints in something that is not epoxy?

I hope all goes well. There was talk about building El Toro dinghies the other day and I almost started moving furniture- that'll fit in the living room, right?

[GordMay]

InterProtect 2000E is an epoxy, and therefore requires that you coat it with a UV stable coating over top, to prevent it from breaking down when exposed to UV light.

[ajay73]

Gord, I would use a polyurethane paint over any of the surfaces I mentioned. A Brightside paint would hold up well enough for a day on the water I believe.

[ajay73]

Spot, that would be great if I trusted another type of adhesive for the structural parts of the boat. Also, I have used the six10 product before and I don't get an allergic reaction. I think that's because I lay a bead of it quickly and then put together whatever parts I'm bonding. With the six10 I don't get exposed to the quantity of fumes that epoxy gives off when used for coating. Plus I don't have to mix resin and hardener. As far as using glass cloth with epoxy I'm told that with the Hydro-tek plywood you don't have to worry about checking of the surface like you do with a fir plywood. It's the checking (small splits) that cracks the epoxy coating and lets water in. So I'm told. I agree though, glassing would be the ultimate method.

[Chotu]

Originally Posted by ajay73

I'm going to build a lapstrake sailing dinghy. The dinghy will never be moored or docked in the water. Just taken to the water each time I use it. Stored indoors in the off season and in season when not in use. I should use epoxy to seal the inside and bottom but I have become sensitized to epoxy when I use it to coat surfaces. I would rather use an epoxy barrier coat (like 2000E) if it would be considered sufficient to protect the wood when the boat is being sailed. I have used 2000E barrier coat and I don't get a skin reaction when I've used it. The hull is being built with meranti hydro-tek BS1088. Lap joints will be epoxied with Six-10 west system thickened epoxy. Would the barrier coat (5 to 6 coats) be sufficient to protect the wood hull? Would using a layer of glass cloth set in a vinyl ester resin work too? I can use poly ester and vinyl ester resins without any allergic reaction.

It’s all an experiment when you’re allergic to epoxy. I get a full on anaphylactic reaction to epoxy now like a kid who can die from peanuts.

The reason you don’t get a reaction to epoxy paint is it doesn’t contain the amine hardener. The hardener is what people become allergic to.

Polyester over wood isn’t so great. It works if ver well maintained. Even epoxy over wood doesn’t hold up over a few years as I had thought it would. Spot is “spot on” about needing to do a layer of glass over it to last. Otherwise the wood still rots.

Here’s what I’d do given what I know so far about non-epoxy alternative construction.

First, get the wood fair.

Next, Put up a layer of really thin veil glass over the entire surface using vinylester. Tiny. Just like 6oz cloth or thinner.

Get some nice thick coats of epoxy primer paint on there to fill any weave you don’t like. It should be minimal anyway, but I don’t know how much of a perfectionist you are.

Then regular finish paint designed to work with your primer.

It’ll last a lifetime or until water gets in from above or something.

[Sherpa17]

I'd go old school and research dories.

[Scubaseas]

Have a look at LBI Fiberglass web site. I have used vinylester on underwater both wood and fiberglass. Has all the benefits of epoxy without the amine. Whatever you use it would work better with any kind of reinforcement like cloth or even .75csm/angel hair. Top coat for UV protection or use a vinylester barrier coat (which is fugly gray or yellow)
No connection to LBI other than very pleases with them for years. Very knowledgeable staff.

https://www.lbifiberglass.com/wood-s...ster-or-epoxy/

https://www.lbifiberglass.com/which-...vs-vinylester/

[garyfdl]

Not a wooden boat builder, but in addition to the comments here, I'd check out 'The Wooden Boat' forum for advice.

http://forum.woodenboat.com/

[Cadence]

Originally Posted by garyfdl

Not a wooden boat builder, but in addition to the comments here, I'd check out 'The Wooden Boat' forum for advice.

http://forum.woodenboat.com/

Ditto! Wooden boats have been built forever without being encapsulated in plastic.

[Sailormanbigd]

I built a Phil Bolger dinghy. I used luan 1/4 inch ply- the cheap stuff. ! layer of 3/4 oz chopped strand mat over the outside, and inside. Sanded and painted with Glidden polyurethane porch and deck enamel. After a coupe years the luan core delaminated. I cut out the rotten wood and glued in some more and glassed back over from the inside. Even the clear fir rub rails rotted. For the rub rails I cut them open from underneath, removed the rotten wood and this time I filled the "U" channel with Bondo glass filler from Walmart. And glassed over it. Super strong with the glass re-enforced filler. The boat was light and strong but the rotten core would have been a disaster waiting to happen. All boats including big DIY cats and tri's eventually delam and have rotten cores that need to be recored. If it were me, I would use a synthetic core material and fiberglass resin. Prime and paint. Or go with straight fiberglass layup and no core. It sucks to go through all the work to build a nice dinghy and then have to redo places a couple years later. I know some can get away with all wood construction and latex house paint for years and years, but not me in central Florida. Or get a rotomolded plastic dinghy- like the one at West Marine and be done with it

[Tupaia]

Sounds like a small open traditional boat. Consider using Tung Oil - should stress "pure" Tung Oil. This is a hard multilayer surface used on traditional Chinese craft for centuries. Is easy to top up from season to season. Just a suggestion.

[ScottRhodes13]

I've had bad luck with Brightside over E2000 on my fiberglass dinghy. The slightest little bump scrapes off the Brightside -- it just doesn't adhere to the E2000.

[ScottRhodes13]

I've had bad luck with Brightside over 2000E on my fiberglass dinghy. The slightest little bump scrapes off the Brightside -- it just doesn't adhere to the 2000E.

[foufou]

I built a cold molded international canoe in 1985 with a meranti outer layer. All West system glue. The outside was covered with 1 1/2 oz glass cloth and west system resin. then washed, sanded and varnished with four coats of Captains varnish. I raced it and sailed it hard for seven years and aside from minor scratches when a friend dragged it up a beach the have been no failures at all. It still looks fine though could use a coat of varnish to make it shiny again. Not all wood core boats fail. multiple sealing coats help cover any pinholes in any one coat. The varnish has the UV protection as GordMay mentioned above.