What adhesive for this?

[ILikeRust]

I just read this thread over at SailNet and I'm hoping Maine Sail will chime in with some words of wisdom here...

So as I previously reported, I have completely torn out the sole and what passed as floor timbers from the cabin in my 1968 Pearson Wanderer.

So what I'm now left with is the bare inside of the fiberglass hull - shown here for your viewing pleasure:



My plan is to make new floor timbers - which will be much, much better than the factory ones that were in there - they were slapped in pretty haphazardly and not fitted at all to the curve of the hull. I plan on using douglas fir two-by stock and fit them carefully to match the curves and contours of the hull, and then glue them in place. I'll paint the whole bilge and the floor timbers with Bilgekote. Then I'll lay down a new sole on those - pretty much just like installing joists in a house and then laying a floor across the joists.

So the question is what to use to adhere the doug fir floor timbers to the fiberglass hull.

My initial idea was thickened West epoxy. Then it occurred to me that there are all kinds of adhesives out there that will hold these things in place just fine and would be much simpler and easier to use than mixing up 2-part epoxy, adding thickener and getting things in place before it cures. Seems to me there should be a single-part adhesive I can apply with a caulking gun that will get the job done just fine and be much easier to work with.

There's not going to be a whole lot of strain on the glue joint - there won't be any force acting to try to pull the floor timbers vertically up off the hull. Maybe a little bit of flexing or side-to-side movement, to the extent the hull flexes going over waves. But not much, really. And they should for the most part be pretty dry - the only water that might get down there will be from the occasional spill or splash from the sink, through the companionway or a dropped drink - or cabin leaks. So the adhesive doesn't have to be something that works below the water line, although waterproofness would be good.

But I've read so many admonitions against using 3M 4200 or 5200. So what else would fit the bill?

Thanks.

[Paulus]

I just completed the task of re-caulking the teak decking on Guillemot - using two part BoatLife Life Caulk (type P), finishing up with a tube of one part BoatLife Life Caulk to build up some of the corners and around the mizzen mast step.

I was impressed with the ease of handling, filling capability and stickyness of the black goop. Now that I am familiar with it's properties, I will not hesitate to use it to fill, hold and glue stuff where black and/or neatness isn't all that much of an issue.

From the manufacturer:

Long lasting, permanently flexible polysulfide sealant. Sand, paint & use above or below waterline. 1-3 day tack-free. Excellent resistance to teak oils, gasoline & diesel fuel. Bonds to fiberglass, wood, metal, glass & itself. Cures to firm, flexible rubber seal with excellent waterproofing & adhesion qualities. Apply to damp surfaces or underwater for emergency repairs.

I believe it might just do well for what you describe.

[Maine Sail]

Personally I would glass them in like any stringer with either epoxy, polyester or vinylester. Coat the limber holes so they don't absorb bilge water and you should be good to go. I'm sure Tim would have the best advice when it comes to glass work..

[ILikeRust]

Personally I would glass them in ...

Can I ask why? Rather than just use an adhesive? Pros/cons, etc? Thanks.

[mitiempo]

The floor timbers should become one with the hull. They add stiffness needed in way of the ballast. I would use thickened epoxy, fillets on each side and maybe glass taped over that. You should have plenty of working time if you are prepared. I would use slow hardener as it gives you more time. Mix the epoxy, wet the bottom of each timber and put it aside. Thicken the epoxy, I would use colloidal silica. You want a smooth peanut butter consistency, just thick enough that it will not run but not dry. Use a putty knife to put it on the timber making sure it is covered more than enough to fill the gaps if any. You want some to squeeze out. Put on the hull in the proper location and press it down firmly. Take a piece of plastic with a round end and smooth the excess into a nice fillet. If there is not enough epoxy add some. Let it set and coat with unthickened epoxy. As noted above epoxy the limber holes as well.

[Hirilondë]

But I've read so many admonitions against using 3M 4200 or 5200. So what else would fit the bill?

And some of them were from me. But usually we were discussing bedding situations, and most things bedded will need removal. And the removal will damage the surface bedded to. Personally I think you have found one of the few applications for 4200 or 5200. Here you are looking for an adhesive. And some day when it is time to remove and replace your sole timbers they can be cut out and the remaining wood stub chiseled from the hull. Chiseling a piece of hardware off the deck doesn't work very well.

I think your assessment of the loads on the timbers is accurate. The most significant forces are to push them down which needs little adhesion to resist the slipping. But you are going to put a lot of work on top of these timbers, so some security is called for. I would think 4200 would be plenty strong.

[ILikeRust]

The floor timbers should become one with the hull. They add stiffness needed in way of the ballast.

OK - far be it from me to disagree with you when it comes to anything remotely related to fixing or maintaining boats - I will more than readily admit I'm way down at the far left end of the learning curve. But in this case, I think maybe what's needed is more of the facts of the situation.

What I tore out - the original, factory installed sole and "floor timbers" - if they can be called that - did not meet your criteria at all. Which makes me wonder whether the new ones need to. Which is why I was wondering whether I truly needed to glass them in versus just gluing them down.

So if you'll bear with me -

The sole was a sheet of 3/4" marine plywood, with a continuous fiberglass/resin tab running around the permiter where it met the hull. I didn't get the impression that that tab did an awful lot in the way of making the sole "one" with the hull. It seemed to me it mostly was to hold the floor down and prevent any water that might enter the cabin from getting into the edges of the plywood. I suppose it might also have been meant to try to stiffen the hull a little bit, but how much stiffening or structural strength would that piece of plywood add, when we're talking about a 1-1/2" thick, 5-6 ton, cored fiberglass hull. The plywood met the hull at a pretty acute angle, too.

The floor timbers, such as they were, were not attached to the hull at all; nor were they even scribed or profiled to match the curves of the hull. They were hunks of oak - which looked like scraps, in fact, of varying dimensions. The ends of the oak timbers had been cut at an acute angle where they came up against the curve of the bilge. But they rested on the hull only at the very tips, or in one or two small places. They basically were big, fat shims, to hold the plywood sole at the right height and approximately level and even. I have to admit I was a bit surprised and dismayed at how it really did look like kind of a quick hack job, rather than a carefully fitted, workmanlike job. In some cases, the oak timbers didn't even go all the way across - just a hunk here and a hunk there.

What it looks like they did was simply lay those hunks of oak across the hull to make an approximately level surface, then laid down the plywood across the oak timbers, and glued and screwed the plywood to the timbers. They laid the plywood in a resin bed around the edges and then glassed all the way around the edge. There was no fastening of any kind between the oak floor timbers and the hull - the timbers were attached only to the plywood sole above them, and not attached to the hull in any way. So when I used my reciprocating saw to cut out the plywood in sections, I could just lift it out a section of sole with the oak timbers hanging off the bottom of it. The only thing holding that whole sole in place was the glass/resin lip.

So now I'm thinking of doing something completely different. From how it was constructed, I got the impression that the floor was not a structural element, at least insofar as providing additional rigidity or torsional stiffness to the hull. It seemed to me to basically be laid down in the cabin and then glued around the edges to keep it there and keep water from penetrating the plywood edges - but I don't know how much that would make it contribute to the structural strength of the boat as a whole.

So if that's right, I'm thinking I can glue down new floor timbers and then attach longitudinal boards to those timbers using screws, to make a floor. Instead of the perimeter fiberglass tab holding down a plywood sole, the glued timbers will hold everything down, because the sole will be screwed to those timbers.

Does this make sense?

Should I do this with the boat in the water instead of on the hard, assuming the hull might flex a bit?

I appreciate all the help and thoughts on this - I'm making this up as I go and learning a hell of a lot along the way, so I'm always glad to benefit from the knowledge and experience of others.

Thanks!

[mitiempo]

I would not duplicate the original sloppy job but improve on it. I have yet to see a well made boat that didn't have either plywood "bulkheads" to sole level, fiberglass beams, or wood beams as you are planning to install. This goes for both internal and external ballasted boats. Maybe not every foot but every 24". Look at Tim's site. Even if the beams are not continuous with the hull he glasses them in solidly. 4200 or 5200 allows a fair amount of flex. A boat needs stiffening and even if not original you can improve on this easily.

Is your hull cored? If so it wouldn't be cored a foot o\r so either side of center in any case.

[ILikeRust]

Yeah, my intent was to do the job better than the original, in any case.

OK, looks like I will be going back to my original plan A and epoxying the floor timbers down to the hull, with some nice big fillets. First thing is I have to do is actually make the damn things!

So much to do, so little time.

Yes, I believe the hull is cored with balsa.

Thanks!

[mitiempo]

The reason I asked is that I don't believe Pearson cored hulls in that era. Decks always but not the hulls. The Pearson 30 that succeeded the Wanderer in 1971 wasn't cored.

[Maine Sail]

The reason I would glass them is to prevent moisture ingress to the wood and the eventual rot. Bilges tend to rot wood, and make it soft & punky. I replaced two backing blocks this week just ten years old and made with "marine" plywood. They were rotted, soft and punky in just ten years. As a kid I helped replace plenty of ribs in my grandfathers wood boat too, most often in the bilge area...

If you don't want to glass over them a more rot resistant wood might be a better choice.

[ILikeRust]

The reason I asked is that I don't believe Pearson cored hulls in that era. Decks always but not the hulls. The Pearson 30 that succeeded the Wanderer in 1971 wasn't cored.

Hmm... mebbe not, then. I should have taken a closer look when I pulled out the two through-hulls about a month ago. I guess the complete answer is "I'm not sure".

[ILikeRust]

The reason I would glass them is to prevent moisture ingress to the wood and the eventual rot.

Roger that.

The good thing is that where these floor timbers will be is not really so much "bilge" as it is just dead space under the sole. I mean, yeah, I guess you'd call it bilge, but it's always bone dry. The oak things that were in there were bare wood and perfectly fine - and I believe they were factory original, so 42 years old.

The real "bilge" is farther aft, under the engine. And even that rarely has more than a cup or so of water in it. It's a pretty tight hull. That water comes mostly from cabin leaks (yet another project for me).

So okey dokey, I've gone full circle back to plan A, which was to epoxy the new timbers in, and now with the added step of glass them down to the hull and glassing over them.

I thank everyone for the input and advice - as usual, this place is great and gets me the info I'm looking for. I figure any day you don't learn something is the day it's time to take your dirt nap.