Probable sole replacement?

[marcusg]

My DS1 clone (Sailstar Explorer 17') has a cockpit sole that's been looking worse and worse ever year. This year I'm not even sure I'll make it through without one of the soft spots giving way.

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I keep her on a lift at our club, and have been sort of mystified as to why the floor seems to be erupting. As in pics, the paint (and maybe even glass?) basically rips open in cracks, I assume from moisture escaping the bilge. The entire cabin sole looks like this mind you, not just a few spots. I've tried leaving the bilge drain open and closed, and I think it's worse with it closed, but I haven't been able to stop the degradation. In general my boat also feels heavier too; I'm guessing most of the sole's marine plywood is saturated, and perhaps part of the delaminated parts of the bilge.

I've scoped/peeked in the square access port (pic) and it also looks like some of my stringers are basically non-existent, save for portions of the fiberglass that encased them, which are still partially standing.

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I'd hoped to limp by for years with not having to do much but repaint the floor, but it seems the plywood core is likely too rotted and exposed to moisture for that plan to work. I saw online that sometimes people just cut out the top layers of wood and glass from the sole, and then lay down new wood on the bottom glass and re-glass the top, but I'm not sure if that would just replicate the same problem. I think it's unlikely that I have great coverage from glass underneath the wood sole core, and that moisture would keep infiltrating and rotting the wood.

My options that I can think of (all include finishing out this season of sailing before working on it, likely next spring, or maybe over winter if I can secure a heated space:)

-Do an exploratory cut out of portions of the sole (of core and top glass layers) and see how much underneath glass is remaining. Pretend the stringer problem doesn't exist. If there's enough glass on the bottom, patch what glass gaps I see and throw in marine ply on top and glass it all on top.

-If I do the above and there's not enough glass to just patch, I'm not even sure what I'd do. Would I laminate the plywood itself and then stitch the pieces together with thickened epoxy? And then glass the top?

-If I get really ambitious and want to tear out the complete floor to get to the stringers, I don't really know where to start. Are those made out of laminated together, bent, marine plywood? I've done a lot of fiberglass repair work but the actual skeleton of the boat is a mysterious to me.

-The lazy approach would be to just let the boat dry out this winter in the wisconsin cold, and then come spring rough up the floor and just glass the crap out of it, relying on the glass to mask any rot problems underneath. Not sure if this is smart or even possible.

Let me know what you think. Thanks.

[marcusg]

Oh and by the way, I did test for leaks from the centerboard bolt and found nothing when I filled the bilge. Nor did the drain plug leak. Someone somewhere mentioned water can just make its way into the bilge through the floor or condensation?

[marcusg]

Can I just sand/pry up the old glass/paint down to plywood, sand, and put down matt and resin and call it good? Seems some places are saying if I use chopped strand mat then it should be plenty strong, despite the compromised wood? I've also read that it might be cheaper to do so with polyester resin, due to cost. I don't really have any experience besides System 3's silvertip epoxy resin, so I wonder what other considerations there are with poly resin. And how many layes of matt...I really have no idea how much resin it would take to wet out the entire sole with thick CSM. 5 gallons?

[GreenLake]

There's a lot here. I've seen it, but I'll need to digest this a bit before making a reply.

[marcusg]

Sounds good, thanks for thinking about it Greenlake

[GreenLake]

I've been a bit busier than expected, and have not even had a chance to look into the forum for a few days. Some of that had to do with an extended DaySail with planned night time return. It was fun, but as it had to happen mid week, it was a challenge.

A couple of thoughts on your post(s), if you haven't already simply done it your way.

First, epoxy is better in two ways: it has better moisture sealing than polyester, but I'm not sure whether vinylester would reduce that gap somewhat. The other is that it is a better glue. Which matters a bit when you make repairs where you can't laminate on top of not-fully cured laminate (which is what gives you the even better chemical bond).

In your case, you are familiar with epoxy, that Silvertip stuff is great and if you are getting good results with it, don't change horses in mid stream.

Your repair will start with removing the damage. That will clarify the picture. Will you be able to lift soggy plywood off some lower layer of glass? If yes, then you are eligible for that repair technique you mentioned.

Any wood that you would place, you would coat on all 6 sides (!) with SilverTip. That way, no water can get in, even if the glass on the bottom isn't perfect. If the bottom glass is in really poor shape, but still presents a reasonably flat surface, you could put one layer of new glass over it, before placing your wood. The purpose for that layer is to add strength, so you'd want cloth, not mat.

(When working with epoxy, you'll want to make sure any mat is rated for epoxy, it will say on the package).

Mat would be used as filler, if the surface is too rough. You could use a layer of that and then a layer of cloth and then place your coated wood on it.

When the wood is in place again, you can then add a layer or two of glass cloth (after making sure any seams around wood pieces are filled with thickened epoxy so your glass has a nice flat surface.

With respect to stringers, the question is can they be extricated from the top? The usual way to build them was to take something like the floor (before it was put into the boat) and to glue some wood on the underslde and then glass over it in an inverted U shape. That U shape may not even be strong enough to be structural.

Cutting a small cross section might help you understand what you are dealing with. Keep it small enough so you can plug it if you choose the repair from the top method.

Here's an alternate idea. Work the way the yard must have done it. They must have molded a floor, then placed it into the hull. You might be able to do the same, but may have to divide things into sections. Assume that we can divide each side into a front/middle/aft section. That makes 6 pieces.

You would use a cutting disk or oscillating saw to saw out a hole a bit larger than your first section, say forward left. Then you make sure that around the edges there's some support. Maybe you can leave the last inch or two of the original floor and bevel it into a consistent shape, replacing any wood there by epoxy with wadded mat.

On your workbench, you build a replacement section for that bit of floor, working upside down, starting with the top glass, then the wood, then the bottom glass, then adding stringers (don't fill them with wood, use builders foam and just make sure the glass cover is strong enough that the foam is mainly a spacer that defines a hollow tube. Some people use paper towel roll cardboard cores cut in half. (No need to add something that could get waterlogged).

When it's cured, you beve the edges so they fit on the bevels in the boat. Having made a good cardboard template should help. Then you lift it into the boat, and glue it in place.

You do the same for the aft (!) section and then do the middle section last. The idea is that you bevel the front and aft section, so they provide support when you drop in the middle section. You can even cut the stringers at an angle to help them interlock a bit. (You can also leave a bit of a finger hole, so you can insert a bit of wetted out glass into a hollow stringer and help tie them together, I think it's overkill, but I wanted to show you that it is possible. You would need to later plug the finger hole -- by cutting the edge into a bevel and repairing it as you would any hole in a piece of laminate. Just make sure that any surfaces of the wood you cut or sand into get re-sealed with epoxy).

I think with either of these method you'll prevent a recurrence of the problem and the floor will be better than new. Just be judicious in how much glass you add. You can check your cross section to see what they did. It may not have been cloth but mat, which isn't very strong. So you might be able to build stronger with a similar amount of material.

To your minimal plans. If you find you cannot lift the wood, then the question is, is it weak/rotting? If so, adding a layer will do nothing. If it is wet, and the moisture came from below, then adding a layer on the top will not help, as nothing sticks to wet wood (for long). Even if you uncover it and let it dry, once it gets wet, it will find a way not even to bond with epoxy any longer.

As for the amount of material you will need, the glass you can estimate by the number of layers and the surface area. Your project is perhaps big enough to really benefit from a test. Why don't you make a 1'x1' section of floor with the upside down method and a bit of hollow/foam filled stringer. You can see how many layers you need to duplicate the existing (or a bit more where that looked insufficient). And you can take a careful note of how much resin you used.

If you can add to the existing bottom, then you'll save some glass and resin, but will have a tougher time fixing the stringers. (You can't cut a channel into the bottom to get the stringers out, because then you've compromised whatever little strength is left in the bottom. At best you could make a series of holes).

OK, thanks for your patience but now you have some suggestions. Start by exploring what is there (excavating a strip 2-3" wide about a 9" long that goes across a stringer) and by experimenting with layup a test section on your work bench. Don't forget to use some plastic sheeting so you don't glue to your bench!

Good luck.

[marcusg]

Thanks as always for the in-depth mentoring Greenlake. Hope your Daysail was fun if learninful.

I'll have to tear into my boat once I get some more good sailing in. Our club (on a pool off the Mississippi) flooded until mid-July this year, so our sailing year was already abbreviated as it was (although I got in 3x before flood and once after so far.)

So it sounds like the lazy approach of just throw f/g and epoxy over questionable plywood is out. Ah well. I'm really curious how much epoxy it'll take to do multiple passes over such a huge area. Dunno if I can stick with silvertip even as convenient as it is ($$$).

Thanks again.
-Marcus

[GreenLake]

The "Sailing Uma" YouTube channel did a bit of a test comparing Epoxy to Vinylester (not plain polyester) and concluded that the differences are slight in the way they plan to use them. The latter is definitely cheaper - but it is a whole different material that you would need to learn. Nothing is worse than doing a big job after having switched methods or materials and then see it fail.

Their boat has 4 times the surface area and 8 times the volume of yours (just based on being twice as long). Actually, it's more than twice as tall, so what is a huge cost factor for them would be much less for you.

I personally would stick to processes and materials I know and have used successfully, simply because a small savings pales compared to having to redo it if something goes wrong.

Epoxy cures more slowly and may give you better working time. It also cures on air, so you don't need to add a layer of peel-ply - all factors that negate, or reduce, the raw price differential. I also like that it doesn't stink up the place.

A thought: you might do some exploration now, cutting out a slice in a place that's out of the way and that you can quickly cover with a temporary patch. That way, it's not either / or with sailing vs repair, but you can work on preparing the latter.