Refinishing coamings--the fine points

[seandwyer]

Hi Guys,

Sailing season is coming up soon and I really want to refinish my combings before it begins. I've read through as much as I can on the site about what different people have used in the past and I have decided that using an epoxy envelope does seem to make the most sense. But nevertheless, I still have some questions that I hope you guys can help with.

First brands--I'm considering West System or System Three. I feel like System Three gets more press on the site, but is it better, or are they all about the same? I guess the clear coat is the product to use. Does anyone have an idea about how much it take to give the combings a sufficient number of coats? The stuff is pretty expensive and I don't want to buy more than I need. Also, when this stuff dries does it tend to stink and combust is pilot lights like oil based paint? If so, I may need to do it in the garage, which means waiting a lot longer than I'd like because it is WAY to cold out there to be messing with epoxy. Hopefully it isn't volatile and I can do this in the basement.

Second--Sanding VS. stripping VS. heat gun. What do you guys think? Could a heat gun or chemical stripper harm the wood? It seems like most guys say they sand them down. I don't want to remove more wood by sanding, but also don't want to ruin them with chemicals or by super heating them. I'd of course be careful not to burn them then visibly--I'm worried about harm that might not necessarily be visible.

I sort of feel like I am refurbishing an antique and I don't want to mess her up if that makes sense. Any help anyone can offer would be really appreciated.

Thanks,

Sean

[dannyb9]

i probably would not use epoxy because it is usually not uv resistant. after a couple of seasons it may become cloudy and begin to peel. if you do use epoxy to seal it, you should add at least a couple of layers of uv resistant varnish.
i refinished mine a couple of years ago (a 40 yo 'classic') using cetol marine, which is a rather thick, soft varnish-like finish. 3 coats are recommended, though i only applied two coats. i sanded the old varnish off. the cetol is holding up well. it has the advantage of being much like an oiled finish- when it ages it is simply absorbed or evaporated so that its easier to refinish than varnishes. it is uv resistant. it requires fewer coats than traditional varnish. its easier to apply.
just my 2centsworth...

[K.C. Walker]

Hey Sean,

I used the epoxy envelope method on my thwarts and coamings four years ago and they still look like new, except where I banged them up. I also used the method on a wooden boat that I restored about 15 years ago. That boat spends way too much time out in the sun and got neglected (the worst part of it). That one looked incredible for about five years and then started to go downhill. After 10 years it looked pretty bad. After 10 years that one got sanded down and varnished again and it looks okay but does not look nearly as good as when I first did it. I used a spar varnish on that one so it did not hold up as well as modern clearcoat.

You have to decide what you want for looks and how much you're willing to do to maintain it. Pristine bright work is beautiful. I'm a real sucker for it but it is a lot of work. Fortunately, there is not much of it on our boats, so you can get a lot of effect for not near as much work. I get a lot of unsolicited compliments on my boat. It has to be the bright work because the rest of it is original gelcoat. If you do the epoxy encapsulation carefully and clear coat it with a good UV resistant clearcoat, I think it's the most durable bright work you can do. I used an automotive clearcoat which was recommended by the owners of MAS.

I used West System for about 25 years and now use MAS, but have never used System Three. I think that any of the three would be an excellent choice. Though, with the West System you need to use the 207 hardener for clear coating. Nick Schrade, the famous wooden kayak builder, lives in the next town. He's the one that turned me on to MAS. I also found that MAS have a carbon fiber spar making company here, as well. I also read a torture test that some wooden kayak makers did using different epoxies under clear varnish. In that test, West did not hold up as well as System Three and MAS held up the best.

Spar varnish is formulated to be flexible so that it can move with wood as it absorbs and expels water. In a lot of cases with wooden boats there is no way to encapsulate the wooden piece so it will expand and contract. With epoxy encapsulation the wood no longer expands and contracts because it is sealed at a certain moisture content. The epoxy encapsulation has to be done carefully and maintained. If you get a ding that goes through the encapsulation you need to touch it up right away. Once you don't have to worry about having super flexible and soft finish you can use a clearcoat that is much more durable and has much better UV resistance. Automotive clearcoat holds up to Florida sun for 10 to 15 years with no problem. A boat in a more moderate climate that is covered when not in use can be expected to last longer than that.

Epoxies are not volatile and don't have any flammable solvents. However they do offgas some sensitizing agent, with a certain amount of exposure you then can become allergic to it. Using rubber gloves and having some ventilation, it's pretty easy to get along with.

Chemical stripper is stinky nasty stuff so you want to do that outside or with good ventilation, actually the same thing with using a heat gun on varnish. I've had good luck with both methods. It's a little easier to damage the wood with the heat gun method, though. It's not actually the heat that does the damage but the scraper you're using to lift the varnish. Sometimes it's easy to get a little gouge. You will be sanding after either one of those methods but I think they are far better than sanding the finish off completely because that's really nasty. If you already have a heat gun I would just try that. If the varnish lifts really easy you are good to go.

Oh yes, do not use oil-based stain under your epoxy! You can use a water-based dye and it will look great.

Enough rambling...

[seandwyer]

Hey--Thanks Guys,

I had been reading about MAS earlier today, so reading what you have to say about it, KC, makes me even more certain that's the way to go. It's what Chesapeake Light Craft endorses and that's where I have been hanging out. So my question (maybe I should just call MAS!) is, if I use MAS, which hardener should I use for the combings? I tend to think the medium or longer acting (slower set time) would be better for me (with my minimal amount of experience), but I'm not sure which is more prone to blush. They all say they are "non-blush" hardeners, but I wonder if one is still more prone than another. For the use of covering the combings, is one better than the rest? Does one produce a harder finished surface than another?

I also am still wondering about how much a typical boat needs. Are we talking about three coats, or something like that? I can figure out within reason how many square feet we are talking about, but I'm not sure about the number of coats.

Also, once I take the combings off the boat, I will inspect the carlings. If they are in bad shape, what species of wood would be best to replace them with? I assume that they, too, should be covered in epoxy as Greenlake made mention of in another string from years ago.

My plan is to use no stains or colorants of any kind. I figure the wood itself has a nice red mahogany look to it, which is what I am after. A lot of varnish and shellac does have a color to it, albeit minor. If I'm going for the classic look, as in when these boats were new, should I consider some minor stain since I will be covering things with more modern products, or will it look pretty groovy all on its own?

I'll call MAS and see which clear coat they suggest. If it's automotive, I assume it is something that is sprayed on. That may be a problem since I really can't see buying compressed air painting equipment, but maybe they sell the same stuff in aerosol cans?

Thanks again guys!

[GreenLake]

What I like about the System Three stuff is what others might consider a downside. They tend to formulate their products for specific applications, rather than selling individual "building blocks". So there's never the question of "which hardener to use for what purpose" (other than using a slow or fast hardener based on temperature).

None of us has the breadth of experience that allows us to have intimate personal knowledge of more than our favorite brands and products, and that's OK.

K.C. gave a number of good answers. For completeness, I'll add two things. One is that the shelf life of epoxy resins and hardeners is very long. So leftovers can be used up over time. I usually purchase the quart of resin with pint of hardener packages of Clearcoat, and one of them would definitely provide enough material to do the coamings and thwarts. With a bit left over, if I recall correctly, which I normally use for other projects.

The way I applied the S3 ClearCoat was by making a "nail bed". That's several strips of wood with long and short nails (with no heads) driven into them with spacing that allows the longer nails to poke through a screw hole in the coaming while the coaming is resting on the shorter nails. The two coamings plus the transom piece can be laide down flat next to each other on top of three such strips that are placed crosswise. I first would coat the back side of each piece, then turn the piece around and do the front. The back side would get small point defects in the coat where it rested on the nails. I would sand/scrape these off before the next coat. They are not visible on the boat.

I would apply the UV protective top coat the same way (I used WR-LPU again from System 3). Half of the small defects from resting on the nails are hidden as they rest against the hull and the other half are really not very noticeable, if sanded down a bit.

One thing to watch out for with the nail bed method is to make sure there are no drips, so it's important to not make each layer too thick, or the epoxy will flatten out, run over the edge and produce drips all along the edge.

Older coamings may have darkened in places. Use denatured alcohol to see where those are, because when freshly sanded the wood will look different, so you wipe it down with alcohol to emulate the coating. If you don't like the darker stains, you could attempt to lighten them with oxalic acid. I haven't tried this on my coamings, but it worked well on an ash tiller. A bit of a stain applied to the wood could even out the coloring. You can experiment on the back side of the pieces, where they rest against the hull.

[K.C. Walker]

MAS is a simple system. They use the same resin and hardeners for laminating and coating. You will want the regular resin not the thicker version. They make three speeds of hardener which makes it really simple. The fast is really for small parts at room temperature or when the temperature is cooler. All three are blush free and they all end up with the same characteristics after fully cured. I think the medium is what you would want. That should give you about a 20 minute pot life at room temperature. Just don't mix up too much at any one time. It's a simple 2:1 mix ratio and they sell pumps that are calibrated. For larger quantities I find it easier to use measuring cups, though.

If you want it to look like a show boat, you can sand and buff your clearcoat, I did... I know, Capt. Overkill The go to Marine urethane around here for the best work is Awlgrip. They make a clear acrylic urethane that can be brushed or sprayed, though you do have to get the right reducer and hardener for each application method.

I used stain on mine because the color was not even. Also, I think that Philippine mahogany, at least mine, was pretty blah looking without some stain.

What Greenlake said about shelflife for epoxy is true of MAS but I found that West hardener goes bad in about a year for me.

If you haven't already, read the West System technical manual on encapsulation. MAS has some videos that I found helpful. I haven't checked out the System Three website but I would guess that they would probably have helpful information, as well.

It's definitely handy to have blush free epoxy but it's not that big a deal to wash off the amine blush. It's just water and a scruffy pad and you're good to go. Even with the blush free epoxy I clean it and scuff it before clear coating.

The nail bed method that Greenlake mentioned works great.

[GreenLake]

Just a PS. the SystemThree is blush free as well.

Also, while I'm happy to report my experiences, by all means get what's easy for you - or what your local store keeps in stock.

[seandwyer]

Hi Guys,

I've removed the combings and am about to remove the thwarts, but have a couple questions.

The thwarts seem to have pulled away from the slots they screw into in the seats, actually bending the screws a little. I'm trying to decide why this may have happened and if the thwarts were just not long enough to begin with, or if something has shifted / spread apart. There doesn't appear to be any damage to the centerboard trunk or the seat, but the screws going into the seat have definately bent. The port side seems to be in better shape than the starboard. This HAS been this way since I bought it, but I have essentially just been trying to ignore it and pretend like it doesn't mean anything bad. Now that I'm about to remove them, I worry that the hull may relax more, or the centerboard trunk move more towards port, or who knows what else could happen. Should I be concerned? Should I try to "pull" things back into shape (I haven't the first idea how I would do that--come-along maybe The thwarts are the same length (both 14-5/8"). The thwart on the starboard side has a gap between its end and the slot in the seat of 1/4 to 3/8" increasing as it moves towards the bow. The port side has a constant gap of 3/16". Should I not worry?

[seandwyer]

I'm also wondering if anyone has any suggestions as to a good way to fix this crack in the end of one of the combings, or at least try to keep it from spreading anymore.

[jdoorly]

Perhaps the trailer or supports were changed, or the boat sat with a lot of water or ice in it. I wonder how much clearance there is supposed to be?

For the split coaming I would either drill through (the hard way) and counter sink both the nut and bolt through it, or take all the finish off, fiberglass a layer of 4 or 6 oz e-cloth with epoxy (s-cloth is stronger but not as transparent). If it was me I would cover the combings with one of these...http://www.uscomposites.com/hybrids.html
just cause it would look cool!

[seandwyer]

I just did some measuring and there is a difference from one side to the other.

From rub rail edge to the centerboard trunk it measures as follows:
port side 36-5/16", and starboard side 36-5/8". I know these boats aren't precise. I'm guessing this is probably more than an acceptable difference from one side to the other and seems to account from some of the difference. The funny thing is that the thwarts measure the same and the distance from trunk to seat measures the same, so the issue must be that the trunk is not centered correctly.

Should I try to reinstall the original thwarts, or should I see about making new ones that fit the specific lengths, port and starboard? What would you guys do?

jdoorly--thanks for the suggestions, but I am in love with the wood on my boat way to much to cover it up

[GreenLake]

Perhaps the trailer or supports were changed, or the boat sat with a lot of water or ice in it. I wonder how much clearance there is supposed to be?

For the split coaming I would either drill through (the hard way) and counter sink both the nut and bolt through it, or take all the finish off, fiberglass a layer of 4 or 6 oz e-cloth with epoxy (s-cloth is stronger but not as transparent). If it was me I would cover the combings with one of these...http://www.uscomposites.com/hybrids.html
just cause it would look cool!

I would regard fiberglass as overkill. When I refinished mine, I just epoxy covered everything, and in so doing, let the epoxy soak into cracks like that. Epoxy can be gap filling, for tight gaps, a rather runny formulation (like System Three's clear coat, or, any laminating epoxy) would probably be fine. If you just put varnish over the crack it will break the varnish, but it would most likely not crack an epoxy coating - esp. if some of it seeped into the crack, where it would act as glue. If you have a very thin spatula, you can force some epoxy into the crack - again, unlike wood glue it would work even if the crack isn't clamped tight. (If you don't want to epoxy seal the whole coaming, you could get away with using epoxy just for the crack, but then I would do it after the first or second coat of varnish, so that you can cleanly wipe any excess and don't get any spots on the front where the epoxy has 'sealed' the wood).

The thwarts are intended to keep the boat together. There's an infinity of possible scenarios where sudden loads might have exceeded what the screws could hold without bending. Sitting with water on the trailer (as jdoorly wrote), "falling" off a wave etc. are all possible. The latter gives a better explanation why only one side was affected - for example if crew only sat on one side...

Have a look at the screw holes. You might decide that you'd want to dig those out, fill them with epoxy and bits of glass, and then re-drill them to fit. I would think there's no need to change the thwarts.

[K.C. Walker]

Sean,

The cracks in your coaming are very minor and not structural. It's best if you can clean them out by sliding a piece of sandpaper in there, if you can't, it's not that big a deal, just do the best you can. Epoxy will fill the cracks and be a plenty strong repair. I would epoxy the cracks before doing the stripping. When you sand everything down after stripping they should be pretty inconspicuous. Use tape on the back side to hold the epoxy from sagging through. It's easy enough to work the epoxy into the crack by pouring it on top and then just rubbing it in circular motion the crack with your fingertip (in a rubber glove) or a credit card as a squeegee. Clamp across the cracks and don't worry if it doesn't pull them totally closed, but it probably will. If you clamp and release a couple of times that will also get the epoxy to work into the fine end of the crack.

If you start measuring symmetries on your boat you're going to find it's really all over the place. It just goes to show, that it doesn't really need to be that precise. When I redid my boat the thwarts were in tight but were different lengths by 5/8 inch. I was doing a bunch of work on the bilge, with my core project. I got measuring and I realized that the centerboard trunk was not in plumb with the mast by about the amount the thwarts were off. Actually, the trunk didn't even line up with the keelson. So I did straighten that out. However, I distorted the bottom of the boat by moving the centerboard trunk without cutting it loose from the hull, so I ended up having to do extra fairing when I did the bottom side.

I do think you want the thwarts tight for structural reasons, I think it's totally possible that they were not fit correctly originally. Though, Jay might have a point about the other possibilities. The fitting at the seat end is a little bit complex, so I decided to reuse the thwarts and added a cheater piece of mahogany on the centerboard end. Epoxy again.

These things that you're dealing with remind me of why I stained my mahogany a little darker.

[GreenLake]

Just FYI while browsing some boating magazines at a foreign airport, I found mention of a "flexible" polyurethane varnish. It combines the advantages of varnish (of not completely sealing the wood, so any moisture wicked into it isn't trapped for good) with the longevity of a PU. The flexible nature would make it more resistant to cracks formed when the wood works from temperature and moisture changes. (They quoted 5 year lifetime for the coating, but I don't know whether something comparable is offered on this side of the pond).

It's because of such cracks that my original attempts to use normal (hard) PU finishes have failed (even where they were marketed for outdoors). Epoxy coating the wood is one way of generating a stable substrate that doesn't crack. I then used a PU coating (admittedly from a different manufacturer) and have now had multiple seasons without problems.

I'm currently thinking of what to do with the floor boards. Getting those sealed tight enough that they don't wick any water will be much more of a challenge than thwarts and coamings, because the latter really don't "sit" in the water for longer periods. Still pondering that, but it's a different topic.

[K.C. Walker]

Polyurethane chemistry is mind numbing for its possibilities of formula. The basis of polyurethane is polyols and their over 300 possible different ones used in the manufacture of polyurethane. Of course, they aren't all used in the same formula. The combinations and permutations are staggering. They range from very flexible to very hard and can be blended to give both a tough and flexible finish. The pinnacle of polyurethane finishes are airplane paints. A coating that can take off from a desert runway with a surface temperature on the plane that might be 180° and climb to the stratosphere where the surface temperature might be -40°, and then the return trip to the ground, and all on aluminum which expands and contracts a whole bunch.

Wood really doesn't expand and contract that much due to temperature but does seriously so due to moisture content. That's why the epoxy encapsulation works so well, if done correctly. If you can stabilize the moisture content, wood is actually an easier substrate than metal for the coating. Automotive finishes are incredible when you think about what they can put up with. Black paint with a clear over-the-top sitting out in the sun in Arizona… or that same car driving around in a salt brine for months on end in a northern Wisconsin winter. These are true torture tests for finishes. Most of these automotive finishes are flexible enough that they are put on plastic bumpers and are able to take stone hits without chipping. 99% of the problems with finish are not the polyurethane itself but the preparation of the substrate.

Though it is a different topic, I think the floor boards are a tough one for trying to maintain a clear finish on. It's just too likely to get a breach in the coating and then it's all over. I think a penetrating finished like Dannyb9 is using might be just the trick. Of course, it might be the trick for the whole job, I've never used it so I don't really know.