Bedding Compound

[Romeguy1]

Hi All,

Due to rot and a failed original canvas cabin roof, I am replacing the plywood sides of my cabin (they're off the boat and in the shop to be replicated).

Where the cabin sides meet the steel deck there was a quarter-round that was removed, which seemed to be bedded in something. No idea what it was, it has been there since 1947.

I've been reading the various posts about bedding compound, and most seem to be in the context of boat bottoms, or for hardware that would need to be removed every so often.

What would you guys recommend that I use when I re-install the quarter-rounds? The vertical surface goes against the wood, with the horizontal surface going against primed steel. Everything will be painted when I'm done, and -knock on wood- will never have to come out again. :D Thanks! ~Jim~

[willmarsh3]

Hi Jim, welcome to the Wooden Boat Forum.

I would consider painting the steel with several coats of high build epoxy and then laying down a bead of 5200. Then set the quarter round in that. You certainly don't want to leave a gap between the top of the quarter round and the side of the cabin.
What is the quarter round made of?

The Metal Boat Society www.metalboatsociety.org might have good suggestions.

Some background: I've got a similar situation - a steel boat with a wooden cabin. The deck is steel. There is a steel flange that rises about 2". The plywood cabin sides are bedded with 5200 and screwed into the steel flange with machine screws. Then a layer of fiberglass and epoxy was applied.
In my case there used to be a wooden deck covering made of 3/8 doug fir plywood with teak strips glued down. This extended under the cabin side to the flange.
Much of this deck covering was getting rotted so I removed it and cleaned up the steel. At this point the resulting gap remains.
http://www.willmarsh3.net/pt/wec_3752.jpg

My main question is what to fill the gap with to make it look nice. I'm thinking of some synthetic material that doesn't soak up water or expand much. Or I might coat some wood with epoxy before putting it in the gap.

[Romeguy1]

Hi Will, thanks for the warm welcome! And thanks for posting a pic of your project. I will do the same when I get to work tomorrow. I don't have photo-editor at home and the pics are too big to post.

But to the task at hand- I would do what you suggest if only I knew what 5200 was or where I could get some. I really am quite a novice at this.

The 1/4 rounds are wood, but I'm not sure of the type. My guess would be hardwood of some kind but I couldn't swear to it. Amazingly they came off in one piece so I'm hoping to reuse them.

~Jim~

[Wooden Boat Fittings]

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Welcome to the Forum.

Judging from the answers to my questions on this other current thread (http://www.woodenboat.com/forum/showthread.php?p=2257890#post2257890), I think I'd be using polysulphide too -- Sikaflex in my case. (I'm not clear whether 5200 is the same stuff.) But there are different grades, and you'd need to be clear to the vendor that you're looking for a bedding compound, not an adhesive.

Mike

[RFNK]

I think I'd be using polysulphide too -- Sikaflex in my case.


Mike's probably right but I do worry about Sikaflex too. I'm currently removing the deck of a boat that has teak decking caulked with Sikaflex (teak decking over glass and a ply deck). All along the teak strips, the Sikaflex has pulled away from the timber, allowing moisture penetration. The last boat I restored had the same arrangement with exactly the same problem. I understand there's a primer that should be used in combination with Sikaflex that's supposed to prevent this but I don't know how effective it really is after a few years. Do you know Mike? Rick

[Bob Cleek]

Sigh... okay, I'll bother... just this one more time.

Don't use 5200 to bed trim... not ever, never, nada! Same for Sikaflex. There ARE certain applications for these products. Few ever encounter one. The last thing you want ever do is use a very aggressive and tenacious adhesive on a part of your boat that you, or her next owner if you sell her relatively soon, is going to have to remove. I guaran-damn-tee you, had her prior owner used 5200, or any of the polysulfide adhesives to bed that trim, you'd never have gotten it off in one piece. You'd still be chipping and grinding and cutting with heat guns and hot knives and cussing the guy out every minute of the job.

What you've got there is TRIM... Trim don't prevent leaks. It just looks nice over whatever is there that is really preventing the leaks... or not preventing the leaks. While well bedded trim may certainly provide a "belt" to go with the "suspenders" of a proper caulking or sealing job, it won't be the trim that carries the day for long.

Here's what you do. First, now that the trim is off, make sure the seam isn't leaking. Clean out the old bedding compound and ascertain what it is that is keeping the seam sealed. It will probably have a metal lip that your cabin sets on top of, particularly if your deck is steel. That isn't going to leak unless a weld is rusted through, which is, children, a story for another time. You aren't going to be worrying about water getting under the lip, really. If you've got a wooden deck over the steel, that may be a concern, but most such decks have the wood laid in adhesive. (Arguably, one possible rational application for 5200.) Assuming you don't run into rot and rust holes, mask either side of the seam with tape, leaving about a quarter inch exposed.

NOW, you actually have an opportunity to properly use one of the polysulfide adhesives! VERY CAREFULLY run a SMALL bead of 5200, Sikaflex or whatever, down that open space between the tape. Be very careful because it WILL get all over EVERYTHING if you are not. Take a putty knife and strike off the raised bead, pushing the goop into the seam and spreading it on either side of the seam, but NO MORE THAN FLUSH TO THE TOP OF THE MASKING TAPE... in other words, FLAT. Let it cure and remove the tape.

NOW you can bed your wood trim. Seal the surfaces that will be covered by the trim. Some use CPES, some use shellac, others varnish or paint if the area is painted. It is important to seal the faying (touching) surfaces... the BACK of the trim where it lays on the wood and the area covered by the trim. Use Dolphinite or an equivalent traditional oil based bedding compound, liberally applied, and fasten the trim. Scrape off the excess bedding compound (while it is still gooey) with a putty knive. You can put what you pick up with the putty knife back into the can, if you want, so long as it isn't full of sawdust and crap. You'll use it again soon enough. Do a final clean up with paper towels or rags wetted with paint thinner, and you're good to go.

Someday, you WILL have a leak somewhere under that trim, and when you do, you will have to remove the trim and do this over again. When that happens, you'll thank me. LOL

[Wooden Boat Fittings]

Sigh... okay, I'll bother... just this one more time.

To be honest, Bob, although your ideas are often very good, next time I don't think I'd really mind if you didn't bother. I dislike being talked down to the way you're rather prone to do. You're not the only one who does it, and almost invariably I get the same reaction. Sharing information is good. Being didactic about it isn't.

Rick, I think there is a primer but I'm afraid I don't know the details. (I only ever used Sikaflex once, and that was about ten years ago, sans primer.) It sounds like Bob's suggestion might be a deliberate attempt to emulate your situation, although I confess I might not have followed him properly. If so, this is just the reverse of what you want, and the primer might be the right solution.

From comments on the "other thread" referred to in my last post, it sounds as though it's not a good idea to use Dolphinite/Dolfinite any more, as the formulation seems to have been changed (which was why I suggested using a polysulphide instead.)

Clearly expert advice is needed, and just as clearly it seems one would need to go to the manufacturer for it.

Mike

[RFNK]

Mike
Actually, I agree with Bob. I'd never use Sikaflex to `glue' timber and I wouldn't use it for caulking decking either (actually, I don't think I'd ever really do the `teak decking' thing at all)! I use it under metal fittings etc. and i think Bob's suggestion of letting it cure first is a really good suggestion. But, I was wondering if the really bad decking caulking job that Sikaflex seems to become after a few years is a basic fault with the product for this application or simply that whoever did it in the past didn't use the primer.

By the way, I think Bob's been responding to queries on this forum for a very long time so maybe it's understandable that he seems a bit impatient or tired when he responds to some queries that have come up over and over. I don't actually think he means to talk down to anyone - I think really we're all fortunate that people with his background remain prepared to respond to the same old questions. Rick

[Wooden Boat Fittings]

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As to your decking question Rick, I've admitted to not being an expert and hence I'm not prepared to offer advice. The only time I ever used Sikaflex (which is the only polysulphide I'm aware of, and I don't now remember what grade it was) was under a pair of deck winches.

Also, I don't necessarily disagree with you about the content of Bob's information. I just don't like the Oh-for-goodness-sake-here-we-go-again method of delivery he uses quite often. Sure Bob's been around a long time. Sure he's probably offered the same advice more than once. But so have I and so have many others, and generally if we've had enough of it we just stop and let someone else take it up instead. I don't see any need for drama about it, and and I know for a fact that the method of delivery can put some people off the information being delivered, even if it's intrinsically good. (And I'm happy to acknowledge that Bob's is, more often than not -- although we've agreed to disagree a couple of times.)

Going back to Jim's original question, it seems to me that what he needs for his situation is a waterproof caulking that's going to stick well to both the steel and timber surfaces. To that extent I think a polysulphide would work okay. If it does I see no reason why, as long as the quad's exterior surface is maintained properly, it would ever need to be replaced. Bob's method, if it's applicable, may be a better one. But if Dolphinite is going to perish and let water in behind the quad, then eventually the quad will have to be replaced. How long that process would take, and whether Jim's prepared to take the risk, I don't know.

This is a quite-typical case where all any of us can do is offer information and advice (preferably from first-hand experience,) and leave the responsibility for the decision to the one asking the question.

Mike

[Bob Cleek]

Let's not make it about Bob. I agree, sometimes I rub people the wrong way, but, hell, if you don't rub people the wrong way sometimes, what good are you to anybody?

What's happened here, over time, is that this forum has become a "go to " place for folks trying to learn about caring for their wooden boats. The same questions come up time and again. The "old fahrts" who have encountered those problems and solved them, often at the cost of their own mistakes (why do you think I rant about 5200? I've been through a few tubes myself!) get burned out on answering the same questions and just don't bother. Then, others, often others with scant experience (present company not included) chime in with misinformation which only gets perpetuated and the new guys learn bad habits and make costly mistakes all over again.

Reasonable minds may differ on many techniques. Boatbuilding is an exercise in making compromises. Still, there are some things that are just plain wrong, like using 5200 as a bedding compound for wood trim. One particularly erroneous concept that just won't seem to die in here is that you can stop a boat from leaking by smearing one or another polysulfide goop on it. Maybe that's because the manufacturers of bathtub sealants call it "caulk," I don't know. One thing's for sure, 3M sells a hundred times more 5200 than there is any good use for.

Sorry to have made anybody feel bad. Maybe it's the way I see the internet. I don't relate to people in these forums so much as I do to the ideas and information that's posted. Just because I find advice wrongheaded doesn't mean I thing the person posting it isn't a fine fellow.

[pcford]

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The only time I ever used Sikaflex (which is the only polysulphide I'm aware of, and I don't now remember what grade it was) was under a pair of deck winches.



Sikaflex is polyurethane, not polysuphide.

[pcford]

Still, there are some things that are just plain wrong, like using 5200 as a bedding compound for wood trim. One particularly erroneous concept that just won't seem to die in here is that you can stop a boat from leaking by smearing one or another polysulfide goop on it.

5200 is polyurethane.

Let's clear this up....

polyurethane:
Sikaflex and its variants
5200 and its variants

Use for stuff you never ever want to take apart. Generally not an appropriate bedding. Never an appropriate seam compound. (Ok, I used it once in an unusual situation.)

polysulphide:
3M 100
Boat Life
Detco 2 part

Polysuphides can be used as seam compounds. Boat Life is pretty much trash. 3M 100 is better. Detco is preferred as a seam compound.

[outofthenorm]

Don Casey has a pretty good summary here: Sealants and Adhesives (http://www.boatus.com/boattech/casey/35.htm)

To put this slap-dab in terms of the question: Use Polysulfides as bedding, not Polyurethanes. Read the labels 'cuz the kid in the boat store probably won't know the difference.

- Norm

[pcford]

Don Casey has a pretty good summary here: Sealants and Adhesives (http://www.boatus.com/boattech/casey/35.htm)

To put this slap-dab in terms of the question: Use Polysulfides as bedding, not Polyurethanes. Read the labels 'cuz the kid in the boat store probably won't know the difference.

- Norm

Good summary...it's aimed at plastic boats so there is not much mention of polysulphide's use as a seam compound.

[willmarsh3]

The 5200 I was referring to is the well known 3M 5200 which is very tenacious stuff.

The reason I suggested it was to act as a water proof cushion between the wood and steel. When I ripped up the teak I noticed where beads of 5200 were used the steel was not rusted. Where they were not placed, the steel had started to pit and rust. The steel had been prepared and painted with epoxy when the boat was built.

As a refinement to the proposed fix technique I might (as Bob Cleek suggested) consider putting down masking tape and the spreading a thin layer of 5200 on the footprint of the quarter round. Then let it cure. Then use a bedding compound suitable for the wood with the idea that you will remove it in the future. Bob is right - it would be extremely difficult to remove the quarter round if it was directly glued down with 5200.

As for posting bad information - My posts are based on first hand experiences and the little bit of knowledge I have. To keep it short, sometimes I put forward an idea that some else then says is wrong or they tell me what is wrong with it. I welcome this input as long as it is civil and respectful as it expands my knowledge. Someday it may help me to avoid a serious mistake. Its not my intent to create confusion.

[floatingkiwi]

Let's not make it about Bob. I agree, sometimes I rub people the wrong way, but, hell, if you don't rub people the wrong way sometimes, what good are you to anybody?

What's happened here, over time, is that this forum has become a "go to " place for folks trying to learn about caring for their wooden boats. The same questions come up time and again. The "old fahrts" who have encountered those problems and solved them, often at the cost of their own mistakes (why do you think I rant about 5200? I've been through a few tubes myself!) get burned out on answering the same questions and just don't bother. Then, others, often others with scant experience (present company not included) chime in with misinformation which only gets perpetuated and the new guys learn bad habits and make costly mistakes all over again.

Reasonable minds may differ on many techniques. Boatbuilding is an exercise in making compromises. Still, there are some things that are just plain wrong, like using 5200 as a bedding compound for wood trim. One particularly erroneous concept that just won't seem to die in here is that you can stop a boat from leaking by smearing one or another polysulfide goop on it. Maybe that's because the manufacturers of bathtub sealants call it "caulk," I don't know. One thing's for sure, 3M sells a hundred times more 5200 than there is any good use for.

Sorry to have made anybody feel bad. Maybe it's the way I see the internet. I don't relate to people in these forums so much as I do to the ideas and information that's posted. Just because I find advice wrongheaded doesn't mean I thing the person posting it isn't a fine fellow.

Why are you apologizing? I don't think it is necessary for you to apologize. If someone has a problem with you or something you have said, then it is exactly that. Their problem not yours. Especially when they are singling out your name and pointing the bone.I don't see you doin' that . Merely expressing your own personal drudge with a particular topic. You are entitled to do that and although it may sound tedious, out comes the worthy info. That is admirable, I think.
Say, although it wouldn't be as enjoyable to get questions answered in such a way, why don't you have a link or two to direct people to information they seek, without having to write it all out again? Kinda like Thorne does with his expanation of how to post pics on the forum.
Don't ask me how I know this.

[Bob Cleek]

Thanks, Pat, for the sound information on "polys." I can never remember which is "sulphide" and which is "urethane" without looking it up and I was just too lazy to do so when I posted. You're absolutely right.

My beef with all the "polys" is their common "more is better" misuse to plug leaks, which in many instances seems encouraged by the manufacturers. I see a lot of barrels made here in the Wine Country and the coopers don't slather them with epoxy or pump the seams full of goop, yet they don't leak a drop. It's a good wood-to-wood fit that keeps those barrels tight when they swell up, and nothing else. Wooden boats are exactly the same. True, age and abuse can undo good construction, but where that occurs, a little hardening up on the cotton, or even a reef and replacing cotton, and a proper seam compound, will solve the problem for another fifty years or more. I've chased more leaks with a "caulking" gun and a tube of goo than I'd like to remember or admit, and I've never caught one for long that way yet. I've learned from my mistakes that doing it right the first time is the quickest, easiest, and longest lasting fix.

Thanks for the support, Kiwi! I agree, but I'll take the time to smooth ruffled feathers, if possible. I realize that, having just turned 60, the older you get, the lower one's tolerance for BS gets. You start to realize you just don't have the time to suffer fools gracefully, I guess! LOL

[Songololo]

In this part of the world, the Sika range of products seems to be generally available...

The Sikaflex, I'll include SikaLastomer in with this group as well, come in a range of 'flavours'. The Sikaflex products are PU based, the SikaLastomer is Butyl based.

The range is marketed as suitable for use as sealants, adhesives, bedding or seam compounds (290 DC).

Data sheets for these products can be found here (http://www.sika.co.nz/nz_ind_prodsel_alphalist_page). A more complete list (although only in German, Italian or French) can be found here (http://www.sika.ch/ind-produkte-suche-sikaflex-pdb).

I have so far only ever used SikaLastomer 710, this for bedding fittings to spars. It seems to remain soft and tacky ... even after a year. When the tube eventually runs out, I'll probably try either 221 or 291.

[Wooden Boat Fittings]

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Thanks for clarifying the issue between polysulphides, polyurethanes, etc, chaps. As I said, it's not an area where I have any expertise. (For instance, 5200 is something I've heard of by name but never even seen, let alone used.)

Bob, I apologise if I ruffled your feathers a bit. Yours was probably a good response -- it was just that the prelude rubbed me up the wrong way. Usually (not always) we do indeed agree about boaty things. And other things as well --

...hell, if you don't rub people the wrong way sometimes, what good are you to anybody?

The Kiwi's taken exception to more than one of my comments in the past, so between us I guess you and I are both good to someone for something....

And -- I realize that, having just turned 60, the older you get, the lower one's tolerance for BS gets.

That agrees absolutely with my experience. But I'm four years up on you and maybe my tolerance level is even a bit lower accordingly. :)

Kiwi, if I understand you correctly, you're saying that Thorne has a guide for newbies on how to post pictures. There was a time when I used to answer that perennial question regularly, till eventually my tolerance threshold was met and I stopped. Norm M. then stepped in and took it over (very well) for quite a while. Then someone else had a go (Pat Cox? Can't remember.) Now apparently Thorne's doing it. (Good for him.) This is an excellent example of exactly what I was talking about in the ninth post.

Mike

[David McCollum]

I found a good use for 3M 5200. A chrome strip fell off of my car bumper. I glued it back on with 5200, and it has stuck very well for 2 or 3 years now. One of its strong points is the ability to stick to nonporous surfaces. Epoxies do that also, but they are not as flexible. I have never used it on my boat, and cannot think of any reason to.

[willmarsh3]

As a bit of trivia the bed logs on the centerboard trunk of the Shellback dinghy are set in 5200 according to the plans.

As for answering the same question over and over there are indeed stock answers on the forum like Thorne's how to post pictures. But they only go so far. I think we all appreciate the efforts of those who like Norm M, Bob, and Pat Cox and many others toil in this effort especially if they provide instruction in the finer points of boat repair methods.

Jim, getting back to your question, the Metal Boat Society has a forum, if you aren't familiar with yet, is a really good resource for metal boats. www.metalboatsociety.org. I'm pretty sure there's information there about how best to bed things in steel. Also Brent Swain has a book on the subject.