Uh-Oh, or not. Forgot the Caulking Seam.

[AndrewT]

So....in my rush to start doing something new (installing new wood is a lot more fun and rewarding than sanding wood I've already installed), I sort of jumped the gun and got a handful of bottom planks installed without back-beveling a caulking seam where the garboard lapstrake plank meets the chine.

The plans called for me to plane the bottom of the plank and the chine flush and flat (it's a flat-bottom skiff), and then to cut a slight bevel in the plank only to allow a thin piece of cotton caulking to be installed after the cross-planked bottom is complete. The bottom planks get a bead of LifeCaulk between planks and between the plank ends and the chines.

Question: How screwed am I? Is the cotton caulking necessary, or will the LifeCaulk coupled with a half-dozen coats of primer/paint do the trick? Should I remove the planks I've already installed and cut the bevel? Should I leave them on, but add the bevel for the remaining bottom planks? Or should I install the remaining planks just like the ones I've already done and disregard the cotton caulking?

As usual, thanks in advance for your input. Wouldn't have made it this far with the assistance I've gotten here.

[Ian McColgin]

The whole thing sounds odd, but it may simply be that you've left out of your description some details.

In a cross-plank flattie bottom, of course the chine logs are planed such that the bottom and garboard land smoothly and completely on their respectives side and bottom.

Normally there's at least a keelson atop the bottom planks and often outer keel plank as well, really just a plank laid on its side, that helps keep the bottom planks from working part. You'll also have duck boards or floor boards that land on the chine logs and keelson so you don't put weight down on one or two of the planks, stressing them apart.

So now, did you just nail or screw on planks touching each other with nothing at all between them? If so, your chances of getting a good seal with anything dribbled in are south of remote. When the planks swell, they will still likely leak but they may likely also stress each other enough to buckle out of their fastenings.

It sounds as if the plans call for a bit of V between the planks. Could be a one-side bevel and the other side from the other plank vertical. An accute enough V that the caulking once in won't be too tempted to squeeze out. Where the planks touch lightly when dry is then such a small surface area that the wood can absorb swelling without stressing the fastenings. The caulking absorbs the rest converting a bunch of planks individually landing on the chines into what's effectivly a single structure, like a plywood bottom but far more durable.

You have messed up. If I read you right. It might be possible to use a very thin V router to make the caulking slots, but it's likely that pulling the planks would be easier. If you pull every other plank you can either plane both sides of it and leave the sides of the other planks verticle. But I think you'll get a better fit to go at it by total removal, even if you're only planing one edge of each plank.

Some argue fore and against priming the edges before installation and caulking. Even if you put the cotton on unprimed wood, at least prime the seam before you pay in the underwater seam compound.

G'luck

[AndrewT]

Okay, allow me to clarify. It is, as you say, a "cross-plank flattie bottom" with the chine logs (and bottom of the garboard plank) planed such that the bottom planks land smoothly. There is a 4"-wide inner keel (keelson) of 1"-thick mahogany running from stem to transom. After installing the bottom planks, there will be a 4"-wide by 1"-thick outer keel installed on top of the planks, as well as two 2"-wide by 1"-thick strakes centered between the keel and the chine on either side (these are only about half the length of the bottom).

The plans do NOT call for floor boards that rest on top of the chine logs; the bottom planks are the floor of the boat inside. The plans and building instructions say to plane the chine logs/bottom of the plank flat, then to plane a slight bevel on the plank only to allow for cotton caulking, then to put a bead of LifeCaulk on the chines and on the mating edges of the bottom planks. I am then supposed to pre-drill for ring-shank nails, three at each chine (these are for 5"-wide planks) and three at the inner keel. Clamp everything down and drive the nails. Plans say not to worry about clamping the planks to each other (to draw them tight) if there are nice, straight edges on each plank - but I'm doing it anyway.

So, to recap - there is a bead of LifeCaulk (about 1/8") all the way across the bottom of the transom (to catch the first plank) and along each chine (I only install enough caulk to allow me to install a single plank so the stuff doesn't skin over before I can use it). I bed the first (farthest aft) plank in the caulk, clamp, pre-drill nail holes, and nail it all down. I then install a bead of caulk along the mating edge of plank #2, another 5-1/2"-long bead of caulk at each chine, and install plank #2, cinching it up to plank #1 and clamping it all down to pre-drill and nail everything. Repeat for plank #3 etc.

Plans do NOT call for V between planks. All plank edges are square-cut. The ONLY caulking (cotton caulking - not the LifeCaulk) is between the bottom of the garboard plank and the tops of the bottom planks, where the little bevel is called for (and which I have forgotten to do).

[Ian McColgin]

Got it. That's more a tight seam approach and so long as the LifeCaulk is put down nice and thin, not used for gap filling, really should work. Do the plans really want 1/8" smear of LifeCaulk

After I wrote my first response I remembered that the thinnish planks used in cross planking don't swell in the problematic ways wider planking does, which is part of why strippers work. Doh. . .

I think you should back out the bottom plank already in so that all the plank/sides seams can be caulked. Otherwise you may be stuck with a most annoying trickle.

It sounds like there are enough attachments along the bottom that the absence of duckboards will be no problem. Flatties I've seen around here are more used by heavy guys and get big loads of clams (if the season's good) and so need that weight spread some.

[AndrewT]

Seams are fairly tight. Plans don't actually call out how much caulk; is 1/8" too much? I'm a former homebuilder, so I'm used to seeing caulk used to fill up big gaps.

Just so I'm clear, your opinion is that I need to remove the planks already installed and cut the back-bevel for the cotton caulking?

[AndrewT]

Also - one more thing to bear in mind. I am not what you would call a "purist." I love wooden boats, but I'm also keen on convenience and low maintenance. If the cotton caulking is for the sake of tradition - i.e. "that's how they've always built lapstrake boats" - then I'm totally okay with leaving it out and just using the LifeCaulk to seal the seam. If the cotton is necessary to water-proof the boat, then I have no problem installing it.

[Jay Greer]

I would use one of two approaches to cure your problem. I would either remove the planking and bevel the seams correctly in order to allow for the caulking. Or, I would glass the bottom. Glassing is far from being my favorite idea. But it will get you by for a time.
Jay

[wizbang 13]

don't forget the hardener

[AndrewT]

I have been told in no uncertain terms by other forum members (presumably with more experience than I have) NOT to glass a solid-wood cross-planked bottom. What about using glass tape, say 6" wide, just at the bottom-to-side joint, instead of the cotton caulking? Would that not a) seal the seam, b) provide some measure of added abrasion resistance, and c) still allow the solid wood to move? The side planks are 1x12 Cypress, so only about 25% of the plank would be under glass, and the bottom planks would only have the last 3" or so at each end covered in glass. I rather like the idea of glassing all the joints and the only reason I haven't pursued it is folks here told me don't do it.

[SMARTINSEN]

Is this what we are talking about? It does not seem to me like it would be that much work to take them off and properly bevel them. That is what I would do, in any event.

Edit to add, after re-reading, that they are nailed, I had assumed screwed. Ring nails, I suppose. You could still probably pry up the mis-bevelled planks, the nails will pull through at which point you could get them off the chine and keelson. Replace with screws in the same locations after you plane the bevels.

Leave the one on the transom, and bevel its mate.

[AndrewT]

That's her. I've only done three planks so far - but they're caulked and ring-nailed. No idea how hard it would be to remove them at this point.

[SMARTINSEN]

Only three? Pop them off, hopefully you have some spare material to replace them if you wreck them. I think you said that they are white pine. Relatively inexpensive and readily available. Or sawcut them, at least from the chines, and save them for the narrower pieces forward. You can do it now, or you can do it later when/if it leaks. One good thing about a cross-planked bottom is that it is easy to re-visit if you have to. A hot knife will probably cut through the not fully-cured caulk.

[Gib Etheridge]

The quickest easiest remedy I can come up with is to use your handsaw to kerf the joint about 3/8" deep and put the cotton into the kerf. You could just shoot caulk in instead. I would clamp a board to the planking to act as a guide for the saw, but that may be over doing it a bit since the saw will naturally follow the seam.

Actually, I don't see any reason not to LifeCaulk the full width (side plank and chine) of the remaining seams as well. It's flexible and won't need re-doing.

[chas]

"That's her. I've only done three planks so far - but they're caulked and ring-nailed. No idea how hard it would be to remove them at this point."

Cut them off just inboard of the garboards and lever from the keelson ; wonderbar is your friend here. Reuse at the bow. As an aside, if the job was further along, would a saw kerf create an acceptable caulking seam in this situation? / Jim

Edited to add my apologies for the repetition.

[Bob Cleek]

Maybe I'm missing something here, but... 1) I'm not a fan of polysulfide goops much at all. I suppose as bedding compound it's okay, but I've never seen any that stretched as much as wood shrinks, so...

Anyway, to the problem at hand, have you considered simply making the seam with a sharp iron (also called a "butt iron"?) It's not at all uncommon to encounter a caulking seam that is too small. A sharp iron is a iron that comes to an angled edge, rather than a squared edge like a making iron. The classic sharp iron is used on ordinary plank seams. It's just hammered in as necessary before the cotton is placed in the seam and it crushes the seam edges a bit, opening it up so there's space to put the cotton. A "butt iron" is used to do the same thing, but its angled edge is sharpened like a chisel. The butt iron's sharp edge, it is a chisel really, is used to cut across the end grain at a butt seam, rather than compress the edges of a plank where the grain runs parallel on both sides of the seam as a sharp iron does. (Have no idea why they call the "sharp iron" that, when it's the "butt iron" that is sharpened, but anyway...)

Now, being as your garboard is butting against the end grain of the bottom cross planks, if I understand your description correctly, the wood grain is running at 90 degree angles at the seam and you've got six of one and a half dozen of the other. I would suggest you consider using a sharp 2" chisel to carefully cut a thin wedge off the END GRAIN, treating it as a butt seam, taking care not to cut into the garboard plank edge. It shouldn't take much if you use a sharp chisel. Attempting to widen the seam with a sharp chisel as with plank edges in line with the grain probably will not work because the end grain will not compress and you'll be putting stress against the fastenings of the cross planking on the bottom. You don't want to pull up your bottom planks. Cutting a small wedge across the end grain is the better option. You can then caulk as normal (by "caulk," I mean drive in your cotton, not smear on goop.)

Just a thought. Your mileage may differ. The suggestion comes from a lifetime of similar mistakes.

[Jay Greer]

Here is another alterative that will allow you to increase your tool skills along with making it unnecssary to remove the planking. A Japanese flooring saw, known as an "Azebiki" can be set up with a depth stop. I would use two sided sail maker's tape and a couple of clamps on wooden battens for controling the depth. This will allow you to widen the seam enough to use a side rabbet plane to bevel the seam in place.
http://www.youtube.com/watch?v=ywug1...ature=youtu.be
http://www.highlandwoodworking.com/k...bbetplane.aspx
Jay

[James McMullen]

I'd say do it right, or why bother to do it at all? On such a small boat, this shouldn't take much time or effort, and you'll be so glad you did it properly instead of just skeeving by when all is said and done.

I think you should saw and chisel off the three you already put on and reuse that planking stock where the boat is narrower. Cut them off, and use a chisel to split out the little stumps that remain. You can get get the nails out pretty easy with vice grips or whatever when the shank is all exposed.

[Yeadon]

You can also heat the ring nails up with a soldering iron, soften them a bit, grab the ends with vice grips and roll them out. It's not impossible, though by the time you're any good at it you'll chew up your planking.

Or do what James said and just reuse the planking further up near the stem where the beam narrow.

[chuckt]

I agree with Bob. I don't much care for life caulk. I think there are better products out there.

[AndrewT]

I agree with Bob. I don't much care for life caulk. I think there are better products out there.

Since I've already bought, received, and opened the stuff, it'll have to do. But just for the sake of curiosity (and so somebody searching for "LifeCaulk" in the future will get a decent result), what are your issues with it? What do you prefer? Is there some reason to suspect that my boat is going to float upside down because I used LifeCaulk on the bottom planking?

I've found that a great deal of stress involved with this project (admittedly, my first) has been due to trying to decide what materials to use when what's available, recommended, or preferred differs from what's called for in the plans. Started off with planking material: 1x12 Eastern White Pine, while apparently readily available and inexpensive in the northeast, is not available in my area. White oak, called out for chines/keel/backbone members, is available, but not very attractive IMO. LifeCaulk wasn't available, WAS recommended (by the designer), and I had no preference or advice to the contrary - so it got ordered. Lots of fasteners were odd sizes and all were silicon bronze - either not available or ridiculously expensive, so stainless steel screws and nails in common sizes got ordered instead.

My guess is, the boat floats right-side up and provides my kids enough years of enjoyment to make the project worthwhile, even if it's not done in the most traditional way and even though I substituted some materials here and there. All of that having been said, I'm still curious about your opinion of LifeCaulk.

[Bob Cleek]

Only three? Pop them off, hopefully you have some spare material to replace them if you wreck them. I think you said that they are white pine. Relatively inexpensive and readily available. Or sawcut them, at least from the chines, and save them for the narrower pieces forward. You can do it now, or you can do it later when/if it leaks. One good thing about a cross-planked bottom is that it is easy to re-visit if you have to. A hot knife will probably cut through the not fully-cured caulk.

Now that I see the picture, I completely agree. If there are only three bottom planks, take them off and use the scrap up by the bow.

[chuckt]

This is just my own personal experience. Maybe I got a bad batch or did an inadequate application. First, I did not like how it went down. It was not smooth and seemed to want to be lumpy and not readily adhere to the wood. I spent a lot of time trying running my fingers around on it trying to get it to fill the gaps and adhere to both sides. And after a few months out in the weather, I have places where it has pulled away from the sides of the seam it is in. And it seemed like it had dried out. I had much better luck with 3M 4200 (not 5200). The only thing I like about the lifecaulk product was that it was available in colors.

Now--I have read posts where the writer says they used it and it performed fine.

If the builder recommended it and you already bought, I would go ahead. Others have clearly used it and were happy with it.

[AndrewT]

I've got the tube in a battery-operated caulk gun (which, by the way, might be the greatest invention ever). But this stuff is HARD to get out of the tube. I keep cutting the tube spout shorter and shorter (therefore making the hole bigger and bigger) and the stuff still just barely comes out of the tube. I have no idea if this is normal or not, but so far the stuff seems to be sticking to whatever it gets onto. I put it on Sunday afternoon; this morning, I went out to poke at it, and it seems to have set up nicely, although it was easier to pull off the wood than I anticipated. I don't really think that's going to be a problem, since the planks are pulled together fairly tight and secured with nine ring-shank nails each (three into each chine plus three into the inner keel). I don't think anything is going anywhere.

Guess I'll find out sooner or later...

[Jay Greer]

Bob is absolutely right! You can get those plankes off using a screw remover on the ring shank nail heads. You can also prick punch the head centers and drill the heads off. This may allow you to remove the planks without damage. Don't waste your time trying to remove the nails. Just saw the shanks off flush and refasten along side.
http://www.jamestowndistributors.com...ct.do?pid=3424
Jay

[AndrewT]

Talked to the designer today; he says 1/16" gap is plenty for the cotton caulking. I believe that rather than try to get the planks off and cut the bevel, I'll try to cut the bevel in-place using either a saw kerf or a chisel. I'll back-bevel the garboard plank before installing the remaining bottom planks. I just can't see the sense in removing the installed planks; yes, I could re-use them in a narrower part of the hull (although I already have all of those planks cut and ready to install), but there's a better than even chance I'd bugger up the chines, garboard planks, transom, inner keel, and anything else that happened to be nearby. If I get a slow leak just forward of the transom in the first three bottom planks, I'll know why (and how to fix it).

[Gib Etheridge]

A local distributor stopped carrying Boat Life Life-Caulk because it has such a short shelf life. If it is too old it gets hard to apply, lumpy and dry and does not form as good a bond as you might wish. If you're having trouble spreading it you might try using Sika 291 or 3M 4200, which is "formulated to allow disassembly".