Small area of rotted core

[helios]

Hi All...

I have a 1977 Scampi MK IV I bought last September. Last week, I discovered that the core around the baby stay tang (just aft of the forward hatch) is all rotted. I dug it out with a coat hanger and the resulting void is several inches in all directions. It seems that the water may have run forward (so slightly down hill) to the hatch, then spread along the edge of the hatch side to side and taken a bit more core with it.

I would like to avoid cutting the top deck off, because I know I'll never match the color or non-skid pattern. Underneath, there is a fiberglass rib molded in which the baby stay tang mounts to. The rot is right above this.

I realize at some point I probably need to cut the deck open to see how far the damage goes and replace the core, but I really just want to get this boat into the water. Is there something I could do to fix it without having to open it, or at least support the deck until the fall?

US Composits makes a two part foam, and it comes in different densities. They have an 8 pound density that they say cures about as hard as a soft wood. Its closed cell foam. I was thinking maybe I could mix up a batch and pout it in. They tell me it will adhere to the fiberglass inside. The hard part is that it expands to 8 times its size and, after you mix the two, you need to vigorously stir it for 25 seconds then you only have 20 seconds left to pour it. They told me it is about the consistency of pancake batter before it starts to cure.

I called Dow about their "Great Stuff" spray foam, but they tell me it needs humidity to cure and then only cures to a 2 pound density, so I doubt that will do the job.

Others have suggested I use liquid epoxy, but that is very thin and who knows where it will run once it is poured in there.

The last idea is to widen the 2 inch by 1/2 inch opening to maybe 3 in by 1 in, then get some core material, cut it into blocks, wet with epoxy and slide them in. But I know that will leave voids.

I would appreciate suggestions.

Thanks!

Jim

[Hirilondë]

I would not pour anything into the void. Without knowing the extent of the rot/damage, and the fact that it is still wet in there, I can see no good coming of this. If it seems that the fiberglass rib and the tang are still structurally sound, and the deck is not overly squishy you might just rebed the tang cover plate, or add one, and wait till next year. It is hard to give this advice as I can't see your boat very well from my house, but waiting may not cause the end of the boat.

When it comes to doing the project properly you will have to weigh the deck matching challenges against the rebuilding the rib and working upside down challenges against each other. But only tearing out something will expose what you need to for a proper evaluation and repair.

[Oscar]

But only tearing out something will expose what you need to for a proper evaluation and repair.

And more often than not it's more than you thought it was.....soooo, plan a period of 3x what you think it will take, and take the boat out of service, as in at the END of the season. In between do as suggested, goop it closed and go sailing.

In the meantime see if you can find someone with a GOOD moisture meter, or buy one yourself and do a little measuring around.....you never know, you may get lucky, find that it is extremely localized and do as you originally suggested.

[Ric in Richmond]

What is under the deck? Maybe you could access it that way!

Probably visible and in the middle of the v berth though I will bet!!

I did the bottom side of a deck in a small spot (about 4x 10) that was not in a visible location. Basically a recore from underneath.

[Jason K]

A recore from underneath adds to the difficulty of the job by an order of magnitude, but it is doable.

It's hard to give you meaningful advice without being more familiar with the installation and the true extent of the rotten core. However, if it's truly only a couple inches, you can mix up a thick mixture of epoxy thickened with colloidal silica (aka cabosil) and fill the void.

I will say, though, that a small area of core damage, or "a little soft spot," is often indicative of more extensive rot than most people expect to find. The right answer is to advise you to excavate core until you find solid, dry core and then rebuild the damaged deck from either the top or the bottom.

[helios]

Thanks everyone, the existence of more rot is exactly my concern. I also realize that if I start this job now I can probably kiss the season good by. I can seal up around the tang, but my concern is that I can press on the top of the hollow deck and deflect it. I'm hoping to get some racing in, and during a race people are jumping all over the place. If someone steps on the weak spot is the top layer going to crack and break?

I did order a moisture meter and hopefully I'll have it soon.

Is there a way to strengthen it temporarily until mid October? I really want to get into the water. In the fall I'll have plenty of time to deal with it.

[helios]

What is under the deck? Maybe you could access it that way!

Probably visible and in the middle of the v berth though I will bet!!

I did the bottom side of a deck in a small spot (about 4x 10) that was not in a visible location. Basically a recore from underneath.

Both sides of the rib are accessible. I could cut a section from each side. The rib is right where the V Birth begins, so I would have 6 inches forward of the rib and 6 inches aft. It's all accessible, just - as others have said - upside down :(

[Hirilondë]

I can seal up around the tang, but my concern is that I can press on the top of the hollow deck and deflect it.

If you can deflect your deck that easily I doubt the wet/rotted core area is just a couple square inches.

I'm hoping to get some racing in, and during a race people are jumping all over the place. If someone steps on the weak spot is the top layer going to crack and break?

I don't know that anyone could answer that, even if they visited your boat. It should certainly be a concern though.

Is there a way to strengthen it temporarily until mid October? I really want to get into the water. In the fall I'll have plenty of time to deal with it.

It would look tacky, but you could cover over the soft area with plywood to reinforce the soft spot temporarily.

[helios]

I went down to the boat today and kept in mind what you all have written and also what I have read elsewhere, and did some checking. First, I have to press fairly hard to get the top deck panel to deflect any more than a tinge. I got brave and stood on it, first lightly and then put all my weight on it. I didn't jump but it felt okay.

Inside, there seem to be three layers. There is the top deck, the bottom and there seems to be a thin layer of wood inside on the bottom. I had noticed that elsewhere when drilling a hole. is there any reason there would be a thin layer of wood below the core material? I also think the deck may be cored with plywood, so maybe its the bottom ply? In that case i don't know why it didn't rot with the rest.

The distance between the layers is under half an inch. Is it normal for a deck to be that thin?

I may put some plywood over the tang just in case, or at least something else thin and hard that does not look quite so bad. Just in case. But I am going to let this issue wait for the fall to be resolved properly, unless I discover a reason its going to be realyl bad for the boat or unsafe. I can seal it up for the season.

Thanks everyone!

[kendall]

Been a response or two of the "wait till you haul it" type. So I'd like to ask, is there a break point where a soft spot on deck moves from the to-do list, to the better get it done now list? Extending that, is there a location dependant break?

Ken.

[Oscar]

is there a break point where a soft spot on deck moves from the to-do list, to the better get it done now list

Yes. An increased probability of structural failure is a safety issue. When I discovered extensive areas of delamination in the hulls of my ama's I had no choice but to get out the power tools as I was afraid that they would come apart.

The above situation sounds like it's not going to get much worse in the next few months, especially if a little goop can prevent further water intrusion, and that there is no imminent danger of things falling apart, short of a 300 pound foredeck person doing the humpty dump right there.....

So, it sounds like it's reasonably prudent to "defer" this item (as we say in airplane speak) until the next scheduled maintenance event and thus not ruin the sailing season.

[bcooke]

is there a break point where a soft spot on deck moves from the to-do list, to the better get it done now list?

When you stroll up to the foredeck and find yourself in the V-berth.

The only way to really know how strong a laminate is, is to take it to its breaking point. So the real question is... "Do you feel lucky?"

[bcooke]

Seriously though, a wet core doesn't really mean imminent failure. The core can continue to function for years even if it is wet. Its going to be a lot more susceptible to the freeze/thaw cycle and eventually it IS going to debond with the skins but that may or may not happen for quite some time.

A cheaper and more visual tool than a moisture meter is a drill- say 1/2 inch. Simply make some test holes into the top skin and look. Afterwards, its an easy thing to fill the little hole with thickened epoxy and you are not going to compromise the long term life of the deck.