Stop me before I do something irreversible

[PJ15Num1]

So I lightly sanded and repainted the deck of my 76-year-old Point Jude 15 sailboat and lots of checks appeared in the desiccated 3/8" Douglas Fir plywood decking. I'm debating what to do next, understanding that some of the options are not easily reversible. Here are the options as I see them and I'm opening it up to the Forum to weigh in on what would be the best way to go:

1. Something that I haven't thought of below
2. Remove all the deck fittings, dig out the putty over the screw heads, remove the decking carefully to be used as patterns, cutout 6 mm Okume ply replacements (or decent Douglas Fir, marine ply, if I can find it) and install them then paint. This is a lot of work and expense, so not my preference.
3. Sand to bare wood as best possible, fair with epoxy and some kind of thickener (chopped fibers? micro balloons? wood flour?), lay-up one layer of 6 oz fiberglass cloth and just enough epoxy coats to leave a bit of the weave texture as overall anti-skid, then paint and apply some anti-skid compound in certain "high traffic" areas. This is my preferred approach at present since the deck is in excellent structural condition with no cracks, holes or rot. This would increase the difficulty of eventual deck replacement, since the deck screws would be hidden under a layer of fiberglass.
4. Sand to bare wood as best possible, spot fair the checks with a 2-part epoxy fairing compound and paint. This would be the easiest, but I'm worried the fairing compound would eventually disbond and the final surface would look "patchy." I'm thinking about using TotalBoat TotalFair epoxy fairing compound or similar in this scenario. I don't know what the experience with this is on old plywood. I would be okay with something that would last 7-10 years as eventually the deck will have to be replaced, anyway, but the 76-year-old decking seems too good to replace at present.

I should note that this is the first example (Hull #1) of a Point Jude 15 sailboat, the 15 foot 'knockabout' "Sharon Potts" in Edson I. Schock's "How to Build Small Boats." It's all original except for the bottom which got new panels in 1988. It's hard to say it's historically significant as it's an amateur-built, little known sailing class, but I view my role as current custodian rather than owner, so I want to keep as much of the original "historical fabric" of the boat intact as possible. I also don't want the next custodian/owner cursing me for doing something stupid.

Would be interested in any thoughts on what would be my best course of action.

I would like to stress that the pictures below are AFTER one coat of Interlux Brightsides applied last summer, so the checking won't fill in with paint. It also didn't penetrate the wood very well and flaked off in spots over the winter (in a shelter.)

IMG_5558.jpgIMG_5559.jpgIMG_5557.jpg

[Rich Jones]

If it were my boat, I'd replace the deck with occume marine ply sealed with epoxy, then paint.
Second option would be to fiberglass the existing deck.

[Figment]

I favor option 3, but don't bother with the "fill the cloth just enough to leave the weave as antiskid". Been there, done that (with dynel), and it's a fool's errand IMHO.

Don't bother fairing before you 'glass it. Fill any large gaps, of course, but then get the cloth on the wood. You'll be fairing after you lay the cloth anyway, might as well just do it once.

Use something like Interdeck for nonskid.

[nrs5000]

I would lean #2 with something other than doug fir. New doug fir ply will check just like the old stuff.

In contrast to Figment I am pretty pleased with my dynel deck and would consider #3, substituting dynel for fiberglass cloth, but I worry that the areas you fair will absorb the epoxy wetting out the cloth differently than the wood, which could really botch things up.

[PJ15Num1]

I would lean #2 with something other than doug fir. New doug fir ply will check just like the old stuff.

In contrast to Figment I am pretty pleased with my dynel deck and would consider #3, substituting dynel for fiberglass cloth, but I worry that the areas you fair will absorb the epoxy wetting out the cloth differently than the wood, which could really botch things up.

What's the advantage of dynel?

[nrs5000]

It makes a nice nonskid surface texture that is very similar to traditional canvas and paint.

[Boatsbgood]

If the Fir is good structurally, I'd for certain be going with #2. Fir checks, unless glassed, but it doesnt take much (I've used as light as 4oz.). But, as above, I'd apply nonskid, instead of glass weave for texture.

[PJ15Num1]

If the Fir is good structurally, I'd for certain be going with #2. Fir checks, unless glassed, but it doesnt take much (I've used as light as 4oz.). But, as above, I'd apply nonskid, instead of glass weave for texture.

#2 is full replacement. I infer your vote is for covering the deck with 4 oz glass cloth.

[Figment]

If you do elect to lay dynel (and not completely fill the weave), then yes fair the deck first, and then roll a coat of unthickened epoxy over the whole deck (and let cure completely, then scuff) before laying the cloth. This avoids the surprise dry spots and flood spots which would result from the differential substrate (wood, paint, filler, whatever) drawing resin at different rates.

[PJ15Num1]

If you do elect to lay dynel (and not completely fill the weave), then yes fair the deck first, and then roll a coat of unthickened epoxy over the whole deck (and let cure completely, then scuff) before laying the cloth. This avoids the surprise dry spots and flood spots which would result from the differential substrate (wood, paint, filler, whatever) drawing resin at different rates.

I'm starting to lean towards stripping all the paint, coating the plywood with un thickened epoxy, faring with the TotalFair, applying another coat of un thickened epoxy and then painting to see how it looks. If not good, sand off the paint and apply 4 oz. glass and fill the weave with epoxy. Then paint and use a non-skid additive in the high traffic areas.

[Larks]

I'm starting to lean towards stripping all the paint, coating the plywood with un thickened epoxy, faring with the TotalFair, applying another coat of un thickened epoxy and then painting to see how it looks. If not good, sand off the paint and apply 4 oz. glass and fill the weave with epoxy. Then paint and use a non-skid additive in the high traffic areas.

The variation that I’d suggest on this is to still glass it after filling and fairing the deck with thickened epoxy and then do any finish fairing with your TotalFair over that before painting.

[jpatrick]

If the deck is structurally sound then it doesn't need the strength providing benefit that epoxy filled glass gives. And since it isn't glassed now, I'd presume that to be the case. If true, then I'd go for dynel without filling the weave. Dynel provides better abrasion resistance than does glass. The unfilled cloth will emulate a canvased surface. It will take paint very well and not allow the fir ply to telegraph through. Unless you're a glutton for punishment, don't put paint on the fir ply. Others have tried and been unhappy with the appearance. And why do something that "might" work?

Jeff

[adamarthurryan]

My experience is that epoxy alone will not stop fir from checking, and that it needs some sort of light fabric. I say glass it - save yourself the trouble in 2-3 years of having to strip it back and start over.

A something else option would be to use canvas and paint. I don't know anything about it, but I'd like to try it sometime. It would be nice to avoid using all that plastic.

[Woxbox]

That fir ply is dead and is not a suitable base for anything. It needs to be ripped off and replaced. Okoume will actually make it a bit lighter than it is now. A light layer of glass or dynel over the fresh, sealed ply and she's ready for another 76 years. And it's really not that big a job.

[PJ15Num1]

That fir ply is dead and is not a suitable base for anything. It needs to be ripped off and replaced. Okoume will actually make it a bit lighter than it is now. A light layer of glass or dynel over the fresh, sealed ply and she's ready for another 76 years. And it's really not that big a job.

The concern I have is removing the coamings and gunwales. That’s a lot of risk of cracking old mahogany and it’s a lot of plugs to trash and replace. Could get a little to big a job for me at this stage. What do you think about Meranti for this application? About 70% the price of okume.

[PJ15Num1]

My experience is that epoxy alone will not stop fir from checking, and that it needs some sort of light fabric. I say glass it - save yourself the trouble in 2-3 years of having to strip it back and start over.

A something else option would be to use canvas and paint. I don't know anything about it, but I'd like to try it sometime. It would be nice to avoid using all that plastic.

I like the canvas idea, too. Like a Beetle Cat.

[nrs5000]

Meranti is heavier but also stronger and more durable/rot resistant than okume.

[PJ15Num1]

Well after meticulous surface preparation including thorough scraping with a continuously sharpened scraper, Citristrip application and more scraping, sanding, thorough cleaning with a Scotchbrite pad and denatured alcohol, drying and contaminant absorption with old terry cloth towels and a day drying in the hot sun, I felt the surface was ready for the penetrating epoxy. So then why did I do the final wipe down with paint thinner instead of alcohol or acetone? I'll be asking myself for years as the deck slowly delaminates. A few minutes of inattention was all it took. I mixed the epoxy with a 3:1 mixed resin to acetone ratio and brushed it on. Instead of wicking in as I expected, it beaded up like a windshield treated with Rain-X. It took me a while to realize it wasn't penetrating well as it took a while to bead. I "managed it" as best possible by going over it with a squeegee as it set up and at least got it reasonably smooth to limit the amount of sanding that will be required. What I learned:

1) DO NOT USE PAINT THINNER OR MINERAL SPIRITS TO PREP FOR PENETRATING EPOXY. These are "oily" solvents and will retard the wood's absorption of the epoxy. Use only denatured alcohol or acetone. Denatured alcohol is preferred.
2) DO NOT USE CHEAP CHIP BRUSHES WITH EPOXY. You will be digging out errant bristles before the epoxy sets and committed to sanding them out after. Try rolling the penetrating epoxy and "tip" with a squeegee.

Probably everyone knows this, but here it is for any who don't. Rookie mistakes.

[wizbang 13]

Grind the fir,one hour .
dynel it ,2 hours
finish the dynel and coat with (i.e.) Interlux 2000,4 hours
go sailing
no citrus goo, no acetone, no mineral spirits,no alcohol,no dumb ass scraper,no penetrating epoxy
RESIN TO ACETONE RATIO ????? wtFLYIN f is that ???

[Ian McColgin]

I've had good luck with getting to bare (or nearly bare) wood and flooding with CPES first. Then use a micro-balloon thickened (easy fairing) epoxy. Then a coat or two of epoxy before paint. If weight not an issue, maybe glass.

[Todd Bradshaw]

Pay close attention to the last two sentences of Wizbang's last post. If there is a number one rule for properly and successfully working with epoxy resin it is to strictly avoid contaminating it with other chemicals, solvents, cleaners, etc. The vast majority of the time it does more harm than good.

[PJ15Num1]

Manufacturer’s instructions recommended thinning with acetone up to 100% of the resin mix. I saw Lou Sauzedde add one part acetone to the same TotalBoat product I was using and got good results.

[Todd Bradshaw]

Solvent-diluted epoxy is a very controversial issue. This is mostly due to the fact that the resin will lose a lot of the physical characteristics that make it good for boat building in the first place, and it doesn't take a lot of solvent to start seeing this deterioration beginning. These would include it's strength, as well as it's ability to seal out moisture. These have been proven through actual tests. It boils down to basically being a primer for instances where no primer is needed for epoxy work. The best exception for this would be using solvent-diluted epoxy as a primer on bare wood for paint, where it may give the paint a longer life (though it may make removing old paint cleanly prior to new painting a real pain in the ass). As a primer for additional epoxy work, don't expect it to improve anything, because it won't.

[wizbang 13]

the guy hoo uses plastic frames

[slacktidemike]

There are a lot of ways of going about these things, and your approach was reasonable. Too bad about the accidental use of paint thinner instead of alcohol. You say you'll have future delamination. Delamination of what? Do you mean you suspect the DF ply will delaminate at some point in the future, or do you mean the coat of penetrating epoxy will come off? You didn't put down any subsequent glass and epoxy, right? I'm not too sure about what you have going on, but it sounds like if the epoxy didn't really penetrate, it should be removed and you should start over. I might try taking a scraper and see if I could easily remove any epoxy as it sounds like it didn't penetrate or adhere well at all. What are you planning to do?

[PJ15Num1]

There are a lot of ways of going about these things, and your approach was reasonable. Too bad about the accidental use of paint thinner instead of alcohol. You say you'll have future delamination. Delamination of what? Do you mean you suspect the DF ply will delaminate at some point in the future, or do you mean the coat of penetrating epoxy will come off? You didn't put down any subsequent glass and epoxy, right? I'm not too sure about what you have going on, but it sounds like if the epoxy didn't really penetrate, it should be removed and you should start over. I might try taking a scraper and see if I could easily remove any epoxy as it sounds like it didn't penetrate or adhere well at all. What are you planning to do?

I was worrying the epoxy may come off. Now that it's fully cured, it seems fully adhered although it beaded in some places and soaked in well in others. I don't see any areas where the paint thinner out-gassed. I should note that I wiped down the deck with paint thinner in the hot sun and let it dry off before applying the penetrating epoxy probably 1-2 hours later when the boat was in shade. Most of the paint thinner probably had evaporated by then leaving a residue only oily enough to cause the epoxy to bead on application, but it must have been done out-gassing since I don't see any bubbles or milky areas under the epoxy. I tried scraping it HARD in a few places and it seems well integrated with the DF ply. I'm thinking I'm going to leave it, mainly because I don't think I can remove it except by grinding it all off and if its on that well, it might be good enough. Anyway, even if I ground it all off, I don't think I'd get down to unpenetrated wood. My plan now is to touch up the areas where it soaked in well and move on to fairing the surface.

[wizbang 13]

why bother asking ?
carry on

[Sandlapper]

The trust in using Dynel in cases like this is apparently bred in and impossible to remove. Dynel will break at the fir checks and patches and it cannot be stopped. Dynel has little ability to bridge even small gaps and I no longer allow it in my shop. There is a much superior material that will not break through at fir checks and patches that will give a great deck surface. Xynole is that common material and it has far superior tensile strength that will not allow such checks and edges to break and allow water ingress.

How Dynel has such a good reputation is a mystery to me as my destructive tests prove. Thin fiberglass like 6oz may work but thicker like 10oz is better and just as easy to apply. Sanding any fiberglassed surface has the chance of going through the fibers which is why we use FG in the first place. Sanding Xynole is an exercise in futility as the fibers just fuzz, making the material very difficult to sand through. This is a good thing for a sheath. If you want a waterproof deck then an impenetrable surface like fairly heavy fiberglass or Xynole will give you that while Dynel is not good. Xynole has the most tenacious grip on a wood surface of any common sheath material and is very hard to tear off while fiberglass can be pulled off in sheets fairly easily. None of these materials should be seen as improving strength of the wooden structure which is where the designer intends strength to be. They should be seen as a sheath but nothing that adds much structural strength.

[PJ15Num1]

why bother asking ?
carry on

I assume you mean why I went with the penetrating epoxy before the poll ended. (?) Few reasons:
1. I have some time to work on the boat now
2. I felt the penetrating epoxy application might work (option 4) or at least would provide a good base for glass (option 3) or dynel (option 1, I guess)
3. If the penetrating epoxy or any of the other options didn't work, I could still re deck (option 2)

[PJ15Num1]

The trust in using Dynel in cases like this is apparently bred in and impossible to remove. Dynel will break at the fir checks and patches and it cannot be stopped. Dynel has little ability to bridge even small gaps and I no longer allow it in my shop. There is a much superior material that will not break through at fir checks and patches that will give a great deck surface. Xynole is that common material and it has far superior tensile strength that will not allow such checks and edges to break and allow water ingress.

How Dynel has such a good reputation is a mystery to me as my destructive tests prove. Thin fiberglass like 6oz may work but thicker like 10oz is better and just as easy to apply. Sanding any fiberglassed surface has the chance of going through the fibers which is why we use FG in the first place. Sanding Xynole is an exercise in futility as the fibers just fuzz, making the material very difficult to sand through. This is a good thing for a sheath. If you want a waterproof deck then an impenetrable surface like fairly heavy fiberglass or Xynole will give you that while Dynel is not good. Xynole has the most tenacious grip on a wood surface of any common sheath material and is very hard to tear off while fiberglass can be pulled off in sheets fairly easily. None of these materials should be seen as improving strength of the wooden structure which is where the designer intends strength to be. They should be seen as a sheath but nothing that adds much structural strength.

Thanks. The 76 year-old DF ply seems sound, except for checking on the surface. I don't have any structural concerns. Mainly, I'm looking for some way to establish a fair surface and allow it to take paint well.

[wizbang 13]

I have not found a difference between the two , in what they do and how they do it.
Dynel is a looser weave, xynole a tighter weave. I know they are different materials, but I find them to be the same final act.
Link to your "destructive tests"?
My experience differs from yours, and I been using it, and abusing it , fer awhile.
bruce

[slacktidemike]

I've used 6oz cloth on DF ply and never had checking. I've heard some say that 4oz cloth will do the trick, but I've always stayed with 6oz. I don't have any experience with Dynel. There is a good build thread - Building the Luzier 16' - and Dynel was put on the deck of a new, DF ply build. You might want to check it out. If the deck is structurally sound, I'd forget about tearing it off and replacing it simply because of some checking. When I first saw the pic of your boat, my first thought was how good it looked for an old ply boat, and, as long as the deck was sound, I'd try to take a low-intensity approach and use a light touch that might not use any cloth at all. But, if you want to nix the checking issue for good, the cloth should do it. I wouldn't try to leave any cloth weave for anti-skid. Rather, I'd fill it with fairing compound and then use a paint scraper to smooth it out.

[wizbang 13]

Leaving the dynel cloth weave to mimic canvas is a theatrical thing.
It sort of looks like canvas for awhile, depending on how rough you are with it, but like canvas, any dings , scratches, hard to remove gunk that gets on it..patching will leave it ...well....patched. The repair will not look like canvas any longer and will be either slippery or need non skid.
Plus, leaving the weave showing is asking for leaks.The weave is NOT SUPPOSED to show.It is an idea whose time never really came.
You GOTTA put some kind of cloth on that fir ply.

[Sandlapper]

I have not found a difference between the two , in what they do and how they do it.
Dynel is a looser weave, xynole a tighter weave. I know they are different materials, but I find them to be the same final act.
Link to your "destructive tests"?
My experience differs from yours, and I been using it, and abusing it , fer awhile.
bruce

You are wrong about the weave of Xynole and Dynel. Dynel has tighter weave than Xynole. Xynole has a loose very open fuzzy weave and looks nothing like glass cloth. I have published the results of destructive testing and have no desire to get into an argument so you can make your own tests and determination.

[wizbang 13]

well one of us is rong