Epoxy over carvel planking gone bad

I saw it written somewhere that one could laminate glass/epoxy over carvel planked house and deck and expect good results. I got tired of repairing the canvas and was looking for minimum maintenance and dryness. I have a 1950 33' Monk Bridgedeck Cruiser. Well, I got hold of an experience fiberglass guy, stripped off the old canvas deck and Irish Felt underneath. We then sealed it all with a coat of epoxy, then laminated (2) layers of 6 oz.glass cloth. I then applied (2) coats of epoxy fairing resin (System Three). Well, after much time fairing and sanding, I had it all looking near perfect. By then I ran out of time, and had to put her back in the water and earn a living once again. She spent the winter in the water and looked fine. Then last summer came around and I went by the boat to check on it and it had horizontal lines which looked like paint runs all over the sunny side of the house. It had been really hot, and for awhile I thought the resin had reactivated. Strangely, The top of the house, where the sun was the hottest, was undamaged. It still looks as good as when I finished it, as does the shady side of the house.

I've done a good deal of research online, and there is much more advice given against what I have done than in favor of it. I must have wanted it to work, and ignored the preponderance of evidence that I was headed for trouble.

So, I'm faced with what to do next. It has been suggested by a few people here in the wooden boat community that I should sand it all off, and finish it in a more acceptable traditional manner. By the way, I live in Port Townsend, so you can imagine the accusations of blasphemy and heresy.

I remember talking to a guy at the Wooden Boat Show a few years ago, and he talked about using truck bed liner on the house top. Would this be a viable solution to my problem? Should I remove all the epoxy/glass first? Please say no. Would the bed liner allow movement of the planking underneath without cracking?

Any advice you can give me would be greatly appreciated. Thanks in advance for your thoughts.

 

It sounds to me like the planks expanded in the heat and the glass coating bowed or pushed out of the seams a bit. I usually see glass crack at a hard spot or where the substrate has moved but perhaps the heat (must have been really hot) caused a different effect. De-lamination at the seams where the substrate "worked".

It is painted right? I'm guessing a dark color? Cabin top white?

My understanding is that Carvel planking is designed to move as moisture content changes. Short of completely encapsulating the wood, I'm not certain how you could stop this effect, or weather you even want to. The planking is designed to move, if you stop this movement then something has to give in the planking, or the frames behind it.

As far as the truck bed liner is concerned, I'm no expert but it would seem that bed liner is a more flexible coating and would perhaps be more forgiving of the movement of the underlying planking.

I'm no Carvel expert but I have helped an older gent at our club with a planked craft so I've seen them up close. I wouldn't have glassed it but perhaps the bed liner idea is worth some consideration as a last resort. I'm hopeful others will weigh in.

Regards,

MIA

 

your mistake was using a brittle epoxy on just one side of the wood (wood expands with moisture, epoxy etc with heat)


using a flexible epoxy paint instead of a brittle raw epoxy resin system would have worked better


paul
progressive epoxy polymers inc

 

Lots of carvel builds have been ruined by the technique you've employed. As a rule, the only way this works is if the boat is disassembled, each piece encapsulated, then the boat is reassembled. I agree with Paul, in that an appropate resin could help, but you do need some previous understanding about the process. I have extensive truckbed liner experence, but this too has it's issues to consider.

I'm currently off the grid and will be back to civil life next week.

 

Most people who know about sheathing to replace canvas use a flexible cloth like Xynole or Dynel. I much prefer Xynole sheathing as it is very flexible and most durable of all sheathing fabrics. Usually epoxy flexes enough for most work but if there is a lot of movement in the planks, a flexible epoxy would be best. Paul Oman can tell you which one to use.

 

"carvel planked

horizontal lines which looked like paint runs all over the sunny side of the house."

Can you post some pictures ? the term "paint runs" doesn't make it appear that the problems coincide with the plank joins, which is what the other posters seem to have assumed.

 

Epoxy over carvel planking photo

I want to thank everyone who responded to my query. I apologize for not responding sooner, but earning a living got in the way. I obviously was mistaken in my judgement to move forward with this project as I did. In defense of what seems to be an uninformed decision, I did put some thought into this. I had read Alan Vaitze's book prior to embarking on this project, and concluded that, with the improved adhesive properties of epoxy over polyester, I could laminate a couple layers of 8 oz. cloth over the carvel planking and have a low maintenance, long lasting deck covering. What surprised me was the relative thinness of the epoxy/cloth covering. I suspect part of the reason for the success of Alan's method was at least partially due to the overall thickness of his lamination. By using a combination of roving and cloth, he effectively built a complete shell over the wood deck, attached with staples, which remained rigid, and allowed the wood structure underneath to expand and contract as needed.

So, back to my situation. Attached is a photo of what I mentioned in my initial submittal. Notice the joint in the planking of the cabin side. You can see the joint, but no distressed areas in the laminate. Below that, you can see a series of horizontal wavy lines. Those horizontal lines are solid resin, not air bubbles. It seems to me that this represents a reactivation, or liquification of the resin due to the very hot 95+ degrees (for the Pacific Northwest) weather we received last summer. I explained this to an acquaintance recently, who had some experience with epoxy/wood laminate experimental aircraft, and he said that is why they always paint these craft white. I read elsewhere that a dark colored surface in the hot sun can register 140 degrees F.

So, I need to decide what to do now. On the good side, 3/4 of the area looks fine. That is, the cabin top, the shady (north) side of the house and deck, and the fore deck. It really puzzles me that the cabin top, which received the brunt of the summer sun, looks great. My guess is that the cabin side, being vertical, caused the liquified resin to run, while the horizontal surface held it in place.

My first priority is to use the boat. So, I'm going to attack this problem in phases. First, I'm going to paint the house and decks an off-white color, and rotate the boat in the slip, so the undamaged side is sun-ward. I'm going to then wait and see if I need to consider stripping the whole thing. Next, I'm going to consider stripping the laminate off the damaged side, and possibly the side deck on that side. At this point, I need some advice. If, say I was mad enough to still want an epoxy/laminate surface, or wanted to apply a polyurethane deck liner product, could I apply 1/2" ply over the epoxy laminate, fastening through the laminate to the wood deck and deck beams or would I need to strip all the laminate off first?

Once again, I welcome your suggestions, and since I'm not all that savvy about computer stuff, don't be surprised if the photo comes in a separate
email.

Thanks all,

Rod Mager

 

Most of the marine epoxies have melt temperatures in excess of 220 deg C. Some specialist epoxies go far higher over 350 deg C. Heat from the sun even with a low albedo surface should not really be an issue other than perhaps high UV degradation. Some epoxies have a much, much, lower melt point, this is engineered in the formulation.

A 70 deg C surface is enough for you to remove your hand (or skin) from it fairly quickly, usually without burning. Much above this and it will burn, I don't like black anodised masts and booms for this reason, even in the UK (lat 51 deg in south) they get hot enough to burn skin.

 

So, its as I thought, nothing to do with the 'carvel' problem, in inflexible resin.

If you just have a case of the 'runs', then you could easily just sand the bad surface smooth, and paint it off-white after you have gotten a better finish on the 'runny' side.

Two scenarios come to mind.

Either, the epoxy was painted on too thick in the first instance, and although it looked smooth at first application, it sagged shortly after. This is very common on vertical surfaces. As the cabin top was fine, maybe this side was rushed ?

The other option, is that you got some hot weather soon after the application, and as it had not been 'post cured', the exposed side ran under the influence of the hot weather.
There is a really good chance that if you now sand the runs down, and paint the surface a paler colour, you will have no more problems. The protected side by now may have done its 'post-curing' enough so that it will not present any future problems.

At this point, I would recommend you just sand the 'runny side' smooth, and then coat the whole wheelhouse pale color, and see what happens. I suspect it will be fine.

The big unknown is the brand and type of epoxy. Some interesting info from West Systems here
http://www.westsystem.com/ss/if-you-can-t-take-the-heat/

 

Photo Attachment

See attached. This goes with my previous post. Thanks.

RMMager

 

I'd be putting a 1" hole saw into an affected area- the sample will give some clue as to the issue- adhesion/resin/rot/whatever? and relatively easily patched

Jeff

 

the picture looks more like delamination of epoxy from the wood

paul
progressive epoxy polymers inc

 

As waikikin said. I'd take an angle grinder to it and see what has happened.
If it's delaminated, grind the affected areas out and fix it.

No reason to look for alternative solutions before you find the cause.

 

Good thing we saw the photos. The bleeding obvious - its only on one plank. As alluded to previously, the wood underneath has spalled, probably from trapped moisture heated by the sun.

Nothing wrong with the epoxy job. Just a lack of proper encapsulation.

As previously suggested, grind it back, remove the splintered timber, refill with epoxy/cabosil mix, and paint.

 

The only time I've seen a sheathing (regardless of resin type) successful on a carvel is if the sheathing schedule rivals the strength of the substrate, which is like embalming the hull/cabin (whatever) in a lot of excess weight, just to fix a problem, likely better done more conventionally.

If this one spot (photo) is all you have, then yeah, just hack it out, back to good, solid material and butter it up with more thickened goo (using appropriate procedures) and prep for paint. Under putty and paint, no one's going to know.

If on the other hand, the sheathing is too light, the wood is moving enough to shear it from the interface and this will continue to spread, probably in an ever increasing fashion.