Coats of Epoxy

Hey guys - quick question.
I put one coat of epoxy on my side panels before framing the hull.
Since it was a couple weeks since the first coat of epoxy I sanded the sides with 80 grit and applied a second coat this morning the both sides.

My question - how many coats of epoxy is common. Should I put another coat on tomorrow or is 2 coats sufficient. Just wanted to know because if 3 coats is the norm, I want to get the final coat on before the 72 hour window expires (do not want to have to sand in between coat 2 & 3 if possible)

I should also add that System 3 Silvertip epoxy is being used. (no blush epoxy)

Let me know how many coats you used on you boats.
Thanks!
Jason

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Permalink Reply by lhedrick on February 14, 2009 at 2:08pm
Jason,

There is no reason to add any more epoxy then needed to fill the weave of the glass. Epoxy alone has no real strength properties. If no glass has been used I don't have an answer for you. Plywood can check over time if glass cloth is not used. So a light glass like 4 Oz in my view is always in order.

When it's smooth enough for your liking it's ready to stop.
Permalink Reply by Jason Knight on February 14, 2009 at 2:46pm
No glass - The hull is meranti, not fir - so checking should not be an issue.
Permalink Reply by Mike Dearing on February 14, 2009 at 3:04pm
I think Larry was talking about glass for strength not checking.

My boat is meranti too and I think I put two coats on mine before varnishing.

Mike
Permalink Reply by lhedrick on February 14, 2009 at 3:38pm
Mike,

I don't build framed boats so, the different methods used by framed builders are new to me. Whenever I have a flat surface like a seat, hatch cover etc. I always cover it with a light glass, something like 4 Oz. mostly to just seal things off from water. For sides and bottom I use 10 Oz glass or kevlar. The glass takes more resin then just brushing it on. I have also have had a lot more luck keeping the finish on with glass then with epoxy alone.

For things like hatch covers which will get walked on a heavier glass also makes them much stronger.

----

A lot of people here talk about oil finishes inside their boat. How does this work out with river sand grinding against it all the time?
Permalink Reply by Randy Dersham on February 14, 2009 at 4:27pm
Mike, thanks for your comments.

Oil has been used on both the inside and outside of the McKenzie framed boats since they are first made. Oil is very easy to apply by just sanding it in, and it's very easy to continue to apply or smooth out a spot of damage. The disadvantage is it should be applied two or three times a season at least. Some do less but most boats, especially newer boats that have less build up, get oil thirsty as they are used in the sun. Some people that want a vintage look still oil inside and out. In fact, the real history buffs pass around recipes for making their own boat oil from a mixture of Linseed Oil and Tung Oil with some extra mojo like pine tar.

Most now use a polyurethane outside. But it is common to oil the interior because wet sanding in a little more oil will usually repair minor scratches or ware.

Oil allows the frames and the chine log to dry. Paint, varnish, or other complete encapsulation methods are easier to clean but can help rot along by trapping moisture inside the lumber and not allowing the lumber to dry.

The major downside of oil is that it collects dirt. Grinding sand is not big deal for oil... it just adds some character to the wood and the interior takes on the well worn wood floor look that some home builders pay extra for. But dirt tends to collect in the corners of the bottom that is oiled and that can be a pain. A strong cleaning once a year and wet sanding in a new coat of oil will bring the boat back to looking great. It is much easier to re-oil than it is to reapply varnish or paint.

Many of the frame boat people are going away from oil and to the encapsulation of all the wood via, varnish or paint. As long as the owner watches all joints carefully and repairs any hint of water incursion then this method can work very well. It is much faster to wash out than oil and it looks so fantastic.
Permalink Reply by Dave Z on February 15, 2009 at 4:05pm
Jason,

2 coats epoxy sanded flat. One boat took 3 to get it smooth enough. Paint over that or Epiphanes gloss.

Inside:
1 qt boiled linseed oil
1 qt turpentine
1/2 pint to 1 pint pine tar (will darken your wood)
a dash of Japan Drier.

Makes enough to do a new boat, and have some leftover for mid season.

I wait for a hot day. Bring the boat out in full sun. This is after it has been hosed out and is fully dry the day before.

Pour the oil in and sponge it around. be as sloppy as you want. let the warm wood soak it all in.
Repeat until it takes in no more. wipe off the excess.

good luck

my big beef with varnish- the floor. If you run boneyards with lots of hidden rocks, you can get impact fractures on your inside bottom. Especially with a hard coated epoxy bottom that won't absorb shock. I good hit and the energy will be transferred to the top most ply (your floor). If your floor is varnished, water will always get in these cracks. You can watch the cracks fill with water, swell the wood and it will turn black. Because of the boats design, this spot is under the front seat. which, you, the owner and rower will always have the best view of this spot!

Even If you varnish the inside of the boat, I'd still recommend oiling the floor.
Permalink Reply by Randy Dersham on February 14, 2009 at 4:12pm
Two coats is all you should need. Unless you are adding to a small area that is uneven for some reason (as along a seam) you should be able to get an even smooth surface with two. Scrape any high spots down with a long sharp edge. Additional epoxy will not add any strength without glass. The extra glass isn't necessary for a Hydrotek or Sapele boat.

Now you need to protect that epoxy with a UV inhibitor. You will still have to sand this coat before you apply your final finish.
Permalink Reply by Mike Dearing on February 14, 2009 at 10:35pm
Larry, I knew what you meant with the glass I just don't think Jason did, I should have wrote it out better.

I've glassed a few places on my boat. One was the bottom, I used whatevers in the kit is that Ray Heater sells. I think its 20oz. s-glass? if I remember right, very heavy duty stuff, took many coats of epoxy to fill the weave. I also glassed the two compartments between the ribs are under where the passengers seat slides with some lighter glass. The reason I did this was on a day fishing trip I hit a submerged rock that I didn't quite see with two very large friends (250+ apiece) as passengers in the front of my boat. The impact broke the rib under the passenger seat, it didnt puncture the hull, but splintered the top two plys on the inside of the boat under the rib. I'll never forget the sound of that rib breaking, sounded just like a gunshot.
Permalink Reply by Jason Knight on February 15, 2009 at 5:38am
Good to know - I will stop at 2 coats and let it cure.
It seems like that first coat penetrated the wood very well and the second filled the little nooks and crannies.
After I get the bottom on I will glass the entire bottom with epoxy/graphite - and be done with epoxy jobs on the hull.

Oil interior - paint and varnish scheme for the rest of the boat.

Thanks for the info guys! Good stuff.
Permalink Reply by Mike Dearing on February 15, 2009 at 5:16pm
Dave,

I wished I would have oiled the inside of my boat. Reason being all the reasons you stated plus getting in and out of the boat you constantly grind sand and rocks into the varnish and literally after one trip the floor does not look as good as the rest of the boat.

In fact if I had it to do over again I would have painted the outside and oiled the inside. I think this is the perfect working mans wood boat finish.

I almost hate to admit this, but I don't really use my wood boat much anymore cause I hate screwing the finish up. It was one the reasons I bought my Willie. We actually call my wood boat the prom queen cause the only time I take it out is to show it off, and the conditions have to be just right.

Being on this site has made me want to start using the old beast again though. There are so many nice things about rowing a wood boat its kind of a shame that mine has sat in the shed with a cover on it for the last four years.

Mike
Permalink Reply by Greg Hatten on February 15, 2009 at 6:38pm
Let's set a date for that Prom. I'll come down the highway and meet you on the Rogue??
GH
Permalink Reply by Mike Dearing on February 15, 2009 at 7:27pm
Greg,

I'd take you down anytime you wanted to go. But the winter steelheadin has been really slow. Im holding out hope for a big springer run though, might be best to wait till then?

Hey also heads up for you, we will be making a canyon run the weekend before permit season May 8-10th and if you want to come along your more then welcome.

Mike

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