Paying material for carvel hull

[jstafford]

I am struggling with my hull on a 42 Grand Banks. I'm in Michigan so she is only in the water about 5 months of the year. I'm about to do a fair amount of recaulking as last splash she did not take up well. A large area of the starboard side was leaking. Over the years I have tried numerous paying materials, 5200, slip seal, interlux brown, lastly linseed putty. I am finding they get hard in the time I am out of the water. Except the slip seal, that's just a slimy mess. Every year I have dug out what I had used the previous year and put in new. That process is getting old. Recomendations? And while I'm asking - should I pull out the old cotton? When do you use Oakum instead of cotton? I know wider seams but how wide?

[wizbang 13]

5200 is devil sperm.
slick seam actually lubes the seam
The two together ,(even different seasons) are never going to work. It's not so much a case of wide or perfectly shaped seams, but contaminated from previous junk,especially that wax.
But what exactly is leaking?
Do you see the seams weeping? Is the cotton knocked through the planks anywhere? Butts? Does she leak the same sitting still as moving?
Have you pulled any cotton? cuz it gets ROTTEN after years of rainwater creeping in there.

[cstevens]

I am struggling with my hull on a 42 Grand Banks. I'm in Michigan so she is only in the water about 5 months of the year. I'm about to do a fair amount of recaulking as last splash she did not take up well. A large area of the starboard side was leaking. Over the years I have tried numerous paying materials, 5200, slip seal, interlux brown, lastly linseed putty. I am finding they get hard in the time I am out of the water. Except the slip seal, that's just a slimy mess. Every year I have dug out what I had used the previous year and put in new. That process is getting old. Recomendations? And while I'm asking - should I pull out the old cotton? When do you use Oakum instead of cotton? I know wider seams but how wide?

I recall that we covered this topic before when you were working to get the boat in the water, right? So much of this may be a repeat. But for what it's worth...

First thing, seam compound isn't the thing keeping the water out. It's the caulking (cotton or oakum) that keeps the boat from leaking. if the seam is leaking after it takes up then it needs to be reefed and recaulked. Adding more seam compound won't solve the leak and may just make things worse depending on what you put in there.

5200 is not a good seam compound for all the reasons that I'm sure you have already heard so I won't belabor that point. Slick Seam is no longer available. Interlux brown compound is the only thing I have ever used and the only thing I have seen used by any of the professional caulkers out here, since the various alternatives have all been discontinued over the years. It does harden up more than a synthetic product like 5200 but it works fine and you don't need to look for an alternative. It's the right product for the job. Again, if the seam leaks after applying Interlux compound then the problem is the caulking not the seam compound.

In my opinion, caulking your own boat is a fools errand. It's a highly skilled task requiring specialized tools and knowledge. Caulking does more than just seal the seam, it also contributes to the overall strength of the hull. Do it badly and you can compromise the hull in a number of ways, by putting shear stress on fastenings or damaging the seam. That said, if you really want to learn how I'd suggest finding a professional willing to show you the basics on a seam or two and then decide if its something you want to do yourself.

Finally, I was impressed that you got that boat restored and launched the first time around. I have no doubt that you will be able to solve the leaks! Best of luck however you proceed.

[jstafford]

LOL, what's leaking? The seams. While she was trying to take up I could see her leaking mostly on the starboard side. No, I do not see anyplace where cotton is to the inside. Sitting vs moving - have not spent much time looking for leaks when moving as I am typically at the helm. On my checks below while moving I have not noticed any big difference. The bilge pumps may run a bit more after an outing. Yes, I have pulled some cotton. In places it has come out pretty clean and others in bad shape. One spot that leaked bad the last splash I did not find any cotton when I dug out the paying. Inside the planks were still tight.

[jstafford]

Yes, I was pretty active on here for a bit. I'm hoping the advice is better this time around.

Yep, I have learned it's the cotton and not the compound. Finally got up the nerve to pound in a bit of cotton last spring and that area sealed up well and didnt buckle so I guess I got the right amount in the seam.
Is there a way to get interlux softer so it goes in the seam's easier?

Not many professional caulkers in Michigan. The last professional I hired you guys were not too crazy about as he likes the non traditional paying materials. I did just hire him to fix the planks where we punched some holes in the bottom. I noticed he didn't set the cotton as hard as I had done.

[cstevens]

There are various ways to soften up the Interlux. The technique I use, which I learned from a professional out here, is to warm the can in a pot of water over a portable burner. It will soften right up. I generally try to get it to peanut butter consistency. If you overdo the heat it will liquify but it will harden again when it cools down and no harm done.

If you are already caulking your own seams with good results then great! I think you should keep going. Make a note of the seams that are leaking then reef and recaulk them in your next haulout. That's the right way to fix the leaks in any case. But do take some care on hardening up the cotton. The thing there is that you can harden up a single seam too far and it may still be ok because the adjacent seams have enough give to absorb the force. But if you harden up a bunch of adjacent seams too much then there is nowhere for the planks to expand to and then you get problems with seams and fasteners.

As for the advice, I guess that's a case of you get what you pay for eh? Take the advice you like and leave the rest. There is plenty of expertise here, most of it better than mine. It's worth the effort to sift through the fluff to get to the useful bits.

[jstafford]

Thanks, got it. That may be where I got lucky on my previous is I only did a small area.

What about the concept that I should do the full length of a plank so it is consistent?

When I reef should I pull out the old cotton or leave it be?

[wizbang 13]

By caulking (banging in cotton) in a small area, you may be "pushing" the leak elsewhere down the line.The leaks can be pushed fore n aft in one seam , or up n down to other planks.
A pro will caulk the tightest seams first, pushing the gaps of wide seams closer together from seams away.
By n by, if the seams are too buggered up, from ripping out 5200, wax contamination, aggressive hammeing or reefing, splining may be a thing for you.
GB is a pretty simple hull shape, splining may be easier than you think.
"Reefing " IS pulling the cotton, not the compound.A special iron is used.

[cstevens]

^^ What Bruce (wizbang) says. Also Louis Sauzedde has a good series of videos on caulking that are worth watching if you haven't already.

[jstafford]

When is a seam too buggered up? At some width? Along that same line, what constitutes a wide gap vs a narrow? I can see gaps that are wider than others but my question is at what width is it considered tight and conversely loose? I have gaps you can see right through whereas others are still tight on the inside. Whats odd was my worst leaker last time was a seam that appears tight on the inside.

My next round of caulking I will take some measurements and see if I'm having an affect on the opposite gaps.

[jstafford]

Yes I have watched those videos as well as all the others I could find on both caulking and replacing planks. From those vids is where I went to the linseed putty(from another old timer). Problem with all that work was I should have put new cotton under it. Now I am looking at taking all that out to do the cotton and I'm seeing that the linseed putty is hard. I did not expect that. I thought it would just be hard on the surface. I have also watched a lot of vids in splining but I don't think I am at that point yet.

[wizbang 13]

We do not, and cannot, know the history of the underwater planking.This was a well built boat that had even seams 40/60 years ago.Someone screwed up along the line.
So far, You have "lol"ed what I've said, and it sounds like you are blowing off my other comments.

I did not learn this chit from watching videos or reading books.
(that said, I would not own a carvel planked vessel).

[jstafford]

Sorry if I offended you. I am trying to understand some basic width concepts. I didn't expect you to know the history of my boat/planks. I was hoping you would share with me some information that was measurable on seam widths to compare with mine.

My response on the vids was to Chris's recommendation on the Sauzedde series. They were very informational as well as others I have watched.

[cstevens]

Bruce is right that videos and books are no substitute for experience when it comes to planking seams (as with so many other things in life...) I'm suggesting them simply because I think it's the best option you have right now. I can't answer the questions about seam width, etc. That's an area where I would call in a pro if I had questions myself. But I think a couple of rules of thumb:

1. Don't do anything to widen, deepen, or damage a seam. Meaning don't use too large a caulking iron or reefing hook, don't muck up the seam edges when you caulk, etc. First do no harm is the best policy.

2. If it's not leaking then it's probably fine. If you can't caulk it without blowing through the other side then you are either caulking waaay too hard (and damaging the seam) or the seam has already been damaged and needs to be repaired. Or the hull could be splined as Bruce says, but that's a topic I have no experience in at all.

(These are also the same things that Bruce is saying here as well. And he has about a hundred years more experience than I do. I just use more words. However his brevity may not work for everyone).

[wizbang 13]

We’re cool jstafford. I sound hard, but I’m not.
b

[jstafford]

Great. So can you share with me your thoughts on seam width?

We’re cool jstafford. I sound hard, but I’m not.
b

[debenriver]

Our general process on new builds was to use oakum below the waterline and cotton above – not always, but certainly on larger yachts destined for extensive cruising.

The two most important things are that the frames are in good condition, sound and not cracked or broken; and that the plank fastenings (screws or copper nails) are in good condition, sound and tight.

If the above two conditions are met, the danger of over-caulking, in my experience, tends to be overstated. Not caulking hard and tight enough is a sure reason for failure.

And I don't totally agree that it is the caulking that stops the hull leaking: it does to the extent that it drives a wedge between the planks so they are set hard one against the other and can't "work" under stress. But the stopping is the final bit of the system that keeps the water out. If the caulking isn't good and tight, then no amount of stopping will stop the hull leaking – but conversely, you do need to keep the water away from the caulking.

I've caulked plenty of hulls where the seams are, in part, a little open on the inside; you bunch up the caulking and drive it a bit more gently until it starts to stay tight – you can see it on the inside but it mustn't hang through. If it does, then either the seam really is too wide or you have insufficiently bunched up the caulking. Where you can see the caulking inside, it's best to paint over it if it's in the lower part of the hull.

You can caulk a hull in good condition quite hard – the skill really is knowing how much caulking to gather to fill the seam correctly. In the UK caulking cotton comes in balls of yarn and you can twist several yarns together to make the cotton the right size for the seam width – a hand drill with a bent nail in the chuck was the usual means of doing this. Here in the US it seems to come like cotton wool, much like oakum does in the UK, and is harder to tease it out and get it into nice coherent strands.

I don't really think there is any rule about seam width as long as long as the planking, fastenings and frames are sound and there is some tapering of the seam, and the seam is not unduly open on the inside. You simply adjust the amount of cotton to suit the seam, so that caulked in quite hard it sits below the surface enough to stop the seams. That depth will vary too depending on plank thickness – with say, ⅝" planking you likely won't have more than ⅛" depth over the cotton. But with say, 1¼" planking you'll have considerably more. It's important to prime the seams after caulking and before stopping up.

As for stopping – traditionally red lead putty mixed with a little grease on the underwater hull and white lead putty above the waterline. Nowadays the International seems to be the best – red below the waterlines and white above. Warming the red in a bucket of hot water does help. It's nowhere near as nice to use as traditional putty, particularly the red. Wiping over the seams with a little thinner will help smooth it.

It will inevitably dry out a bit over the winter. I've found that you can mostly thin it a bit and trowel the thinned compound into the cracks in the seams; but if it's got loose you have to rake it out carefully and re-stop.

Cheers -- George

[willin woodworks]

There are too many variables at play to use seam width as an accurate barometer of why you have leaks or which seams will leak. There is no one answer or one hard and fast rule.
The advice given so far by those that know is spot on. Go slow, be careful; as someone already said "Do no harm". Resist the urge to just yank stuff out and pound new stuff in.

[wizbang 13]

At the end of post #4, You mention that,
"One spot that leaked bad the last splash I did not find any cotton when I dug out the paying. Inside the planks were still tight."
This is a bit of a telltale. An un caulked area .
Someone dropped the ball here, this person might have dropped the ball elsewhere.