Boat Builder Central - Builder Forums

My apologies if this isn't the right forum for this question; it's sort of about the wood, but maybe the repair part is about epoxy...

Here's what the problem is: I built a D4, epoxied the boat and used System 3 primer and paint. There are a number of very thin (hairline size) cracks in the paint on the bottom of the boat in some places. After a day in the water, the area around these cracks are slightly raised, suggesting they absorb some water, and then after a few days in the hot, dry garage (I live in a warm area with low humidity) the swelling subsides.

Earlier, I sanded down one area where this was happening, re-epoxied and repainted. A couple of these cracks have returned, but some have not, but new ones have appeared.

My hunch is that there was some moisture in the wood initially, this caused swelling and cracking, and now that the cracks are there, they absorb some water.

My questions are the following: Can anybody tell me what is causing this? What will the consequences be if left unrepaired? And, what can I do, if anything, to permanently repair this?

Thanks,

Andrew

Question: did you build with fir marine plywood or pine plywood? If so you may just have some checking of the ply surface veneer. There's plenty of info on checking on this forum so just do a search.

MikeS

This may simply checking. Tell us what type of plywood you used.
Fir, pine etc. will check.

I suspect it was pine. It was relatively cheap wood from Home Depot. I have the receipts somewhere, but can't find them. Anyway, it was your "basic" plywood.

I'll do a search for "checking" if that's what you think it is.

Andrew

You just answered yer own question-if it was depot plywood, it's fir, it's checking and it's a problem you'll never chase down...

CMP

OK, if I can never fix this problem, then what can I expect it to do to my boat?

Andrew

Hello Andrew,

I put 4 oz cloth over all my doug fir on a Caravelle, 6 oz on the outside of the hull. No checking in two years, but, its not quite in the water yet either. I'll know next fall if temperature extremes (trailer over hot asphalt into cool water) cause checking that even the 4 oz cloth won't stop, but I doubt it. I think the checking issue is history. I put the cloth on all frames, AFTER tabbing them into the boat. I put 4 oz on the bottom of the seat tops, and in the cuddy and on the floor. Yes, it is a little heavier, but no checking anywhere. Doug Fir is stiffer, and heavier than Okume, but the Home Depot stuff is a gamble. Might have cheap rottable softwood in middle laminate, depends on the source and the batch. I'll go marine doug fir if I do doug fir again. But I think it might be BS1088 Meranti, which I can't afford, but will wait til I can, because I am now very labor conscious and would rather pay for better wood then spend so much more time fixing and dealing with a lesser grade. But that's me. Labor is as much a cost as buying the wood, and it will tell on you when you take on a bigger boat, not that the building isn't fun, but it is also fun to be on the water sooner!

Put cloth on that Doug Fir and you should be OK, but if there's a lot of water in there already, the clock is ticking. You may get more years out of it if the water was salt water, but that is a debate amongst some. Maybe worth the effort of 6 oz cloth in the spring and then enjoy the boat until it turns to jelly. You may find that even with water in there already, you get many years yet out of it. Tap around suspect areas every now and then. You'll probably hear if things are going bad in the plys. And again, you may get many years out of it yet. Troublesome problem if the boat is in the water all season, but you're talking about a D4, right? No offense. Since it is a Home Depot special (no less valuable to you), you would not be loosing thousands of dollars if it becomes a jelly boat. 6 oz cloth on a D4 may be extreme to some, but it may give some experience for your next bigger boat! But, having built a Home Depot boat myself, I suggest the extra bucks for marine ply for the next one. Considering the labor you may invest, the wood cost is proportionally not that much greater for the marine grade, which is now sold through Bateau if you do not have a satisfactory or trustworthy local source. SInce you already built a boat, getting a few others to build with you on the next one may help pay the shipping cost of ordering from out of town (if no local trustworthy source).

Refinishing when you don't want to is a pain, but go ahead and glass it up and get it back in the water. I wouldn't glass the inside of a D4, but if you start checking in there too.... bail, sponge, dry, and enjoy while it lasts. You're next one may take half the time, and if you use Okume or Meranti you may discover a new joy that Home Depot simply doesn't provide in the character of its Doug Fir supplier's plywood. Home Depot does not purchase for boat builders so I do not think I'm offending them! Whatever you do, enjoy and get ready for the next one.

Marine Doug Fir checks as much as Home Depot exterior. It has to do with the nature of Doug Fir and how they peel it off the bole when manufacturing plywood from it. But Marine has 5 plys where HD has 3 plys, which adds strength, and perhaps more stiffness, and there ought to be better QC, ie, fewer voids to have to fill with epoxy (so they don't become water reservoirs if water does get in there). I spent around 10 hours with slow cure epoxy and syringes filling inner ply cracks and voids in the best HD pieces I could find for my first boat. It is a rite of passage I suppose. Welcome to the club!

sincerely,
ks

Andrew; If at all possible, apply a layer of lightweight glass cloth in epoxy resin to your boat. No more checking! Otherwise, just use the heck out of your boat and don't worry about it. The boat may not last a lifetime, but 10 or 12 years from now you'll still be enjoying it. If it does rot or delaminate, build another one!

Thanks for all the tips. If I get 10 years out of it, I'll be happy (I think it cost me about $380 to build). Had I known this would be a problem, I probably would have searched for better wood, but I didn't know. Live and learn, or build and learn, I suppose.

I may consider glassing the bottom, but I'm not crazy about the extra weight, and doubt I will ever convince myself I have the time anyway!


Do you suppose the boat will give me a warning before it sinks, the way a rattle snake rattles before biting...?

It doesn't have to sneak up and bite you before it sinks. Every season, tap around with the handle side of a screwdriver, all around, on the bottom of the hull and a bit up the topsides. You'll know if you're growing jelly, and even then, depending on how bad its got, you may be able to do a fairly quick repair, but it will require taking down the finish to *see* how far the goo has gone. Enjoy in the meantime, particular since it sounds like the money investment was minimal. I'm tempted to do a quick D5, but not until after the Caravelle has dipped in the briny.

ks