Mast step leakage and repair questions

[BruceW]

Hi folks, new problem to work on.

Situation: I saw some dark water leak out from between my front hatch and the mast step. Ugh. So, I opened the hatch and saw the leading edge of that built up step formation had cracked gelcoat. Upon further review, the trailing edge had a spot where it was puckered out. So, I took the hatch off, and chiselled out the damaged gelcoat. I got to wood right away, in other words the wood in there was flush to the molded raised portion.  It was damp but solid. I'll post pictures from my phone, since that's easier for me; the typing is easier on my computer so I'll proceed here first.

The trailing edge was different. The chisel went right in, and I took out soft surface gelcoat/glass for about 4-5 inches, about an inch up from the flat deck. What I found  here was junk filler, very wet, and the wood was recessed about half inch.

Next step was consult some guys at the club. We/they tapped the mast step area, found it mostly solid, with void across the trailing edge, but very solid structure. Didn't find any rotted wood.

I called Keith Scott, and the summary was, well, some years had a known void issue, so check for compression front to back. I did that, and there wasn't compression, so that was a less bad sign.

Here's my plan: let it dry, haha, but only while I'm there. Then I sealed it up when I had to come home (I live 2.5 hours from the club). I have a week's worth of rain to live through, and then a week's trip to take,and so about two weeks to flesh out the drying strategy and the epoxy products, etc that I'll need.

I have looked up epoxy, and found there are some that can go in via injection to penetrate the wood: Git Rot, Smith's, etc.

I have found some expoxy from Paul Oman that purports to be better in marine environment, and I can get that, and some syringes and figure to use it.

To protect from rain and dry the boat out, though, I have my biggest dilemma. To fix in situ, I'd just need some luck with the weather. Or, I could haul boat, figure out the mast lowering for this CP 23, move mast to the side, and upend a tub over the area, and tape that down when I leave. This might work for protecting from rain, and so on. Having mast down will let me caulk the tabernacle screws. Oh, I didn't find evidence of any caulk used for the hatch cover, so I"ll drill them out, epoxy fill, and drill smaller hole into the resulting plug.

Next, what epoxy and methods should I use? The pictures to follow will show the gouges I made, the pilot holes in top, etc, for reference.

I'll say this: plan A is to fix in place, plan B is the whole hog cut this mast step off, order the replacement stuff from Gerry Hutchins, and have a PITA with fixing it from scratch.

Okay, next thing I"ll do is post the pictures.

Thanks for reading.

Bruce

[BruceW]

This is the trailing edge, which was soft and wet, but the wood was strong.

[BruceW]

The leading edge, where the wood was flush with molded mast step, and not wet. There was a gap on left side, where filler was mush I think the side is all filler front to back, for about half inch.

[BruceW]

Here you can see the top view, with the pilot holes I drilled to allow air to flow, find the soft spots (the holes on starboard side are all into mush; the holes to rear of mast step are only mush for the first ones nearest the gouged out part).

[relamb]

I think there are some posts from people having this same issue on CP16s and what was done to repair it.  Here's my two cents (having not tried this).   If I wanted a permanent repair, I think I would take a dremel tool and little cutoff wheel and go all around the outside of the raised mast step area, slicing into the vertical wall all the way around.  Then assuming the entire thing is cored with plywood, I would very carefully take a chisel, hacksaw blade, etc and split that wood to get the top molded piece off.  Now that you've opened the sandwich, carefully dig out all the wood with a chisel, router, etc. on both the removed top piece and the wood that's left in the cabin top, grind it out with the dremel or whatever.  The key is to get out all the wood, but not destroy the thin fiberglass skin.  Now take some other type of core material (or plywood again, if you dare) and epoxy,  and fill the bulk of the top skin with it making sure there are no voids.   I would let the top piece cure at this point. Tape off the deck so you don't get any excess epoxy all over, and put a layer of epoxy in there as well.  Butter up the top piece with thickened epoxy, and put the sandwich back together.  Try to get the right amount of epoxy so it squirts out the cut line where you severed the two pieces with the dremel, but you don't want it running out everywhere.
Now you have a solid mast base again, and just need to sand and clean up the vertical joint all around.  Use a little sanding drum on the dremel or a wood block and conform to the contours.   Paint if the epoxy doesn't match the color of the deck, or use tinted epoxy to fair and smooth over the joint.   My biggest concern with this whole concept is making sure you can split the plywood of the mast base, and route out all the old wood, without cracking the skin.  Depends on how thick it is.  If you crack or break it a few places, it won't be that big of a deal, epoxy it back together.  If it's really thin, this approach won't work.  You can probably tell the thickness by the holes that you drilled. 

[BruceW]

Well, I sure couldn't find any threads about this; I appreciate your comments.

Since the wood appears strong, and the tap test showed solid most everywhere, what is your reasoning for taking up the skin and basically starting over? Seems to me that injecting epoxy in there after it dries would work. Oh, yeah, after it dries; that is going to be interesting.

Bruce

[relamb]

Plywood is not the greatest coring material, because it weeps water sideways through the plies and continues to rot and delaminate.  Plywood boats covered with epoxy/fiberglas are bad news for that reason, if the encasing plastic ever gets compromised.  Newer boats use end-grain balsa, the wood is cut across the grain and water does not wick through it sideways.  or they use some other composite material, often honeycombed to save weight vs solid fiberglass.

There's nothing wrong with getting out all the soft stuff, drying it out completely, and sealing it off with epoxy.  As long as there are no cracks anywhere so that water can get in and it can happen again.  The issue gets to be drying it out, and keeping future water out.  If it's not completely totally dry, even if you encapsulate it, the moisture can expand and contract due to freezing/thawing and it can eventually make more little cracks, and then water will get in someplace else.  So the problem continues.
But this could take years, and if there's no weakness of the structural integrity yet, you don't really have to do much of anything.  Dry it out as best as possible, and you could even just seal it off with caulk.  The advantage with caulk, although it might not be pretty, is that it's flexible and if there is some flexing, or expansion/contraction from entrapped moisture, the caulk will flex vs cracking and retain it's seal.  epoxy will crack and let in more water.

I once bought a new offshore fishing boat, and the transom was made to handle several hundred horsepower outboards.  It was about 2" thick, made up of the fiberglass outside layer, at least an inch or more of marine plywood, and a 3/8" aluminum plate in there as part of the sandwich.  I trailered it back and forth between FL and the great lakes.  The expansion/contraction of that aluminum plate inside over the seasons, vs the relative stability of the fiberglass and wood, caused a split in the top of the transom, and water would just run down in there between the fiberglass and the plate.  Drying it out and filling it with epoxy did no good, because moisture had wicked so far down inside along that plate that it would crack again after a few freeze/thaw cycles.  It never really affected the structural integrity of the transom even after 12 years, but it didn't look good to me.  When I sold the boat, the buyer's marine surveyor suggested drilling some holes in the transom at the maximum intrusion point (his moisture meter showed moisture at least a foot away from the edge) during a dry low humidity period, getting a vacuum pump and sealing it all with plastic and duct tape and try to pull a vacuum so it would suck dry air in through all the cracks and eventually dry it out.  Then pour thin epoxy into the cracks and try to suck it in/through as far as possible.  He suggested holding this vacuum over a period of 2-3 weeks.  ...or taking the boat to Arizona for the winter.  Otherwise, I'd never get the moisture out.  However, my alternate theory is that it would not matter, because with that aluminum plate still buried in there, it would expand/contract and start things all over again.  My eventual solution was to just dry it as best I could, caulk the crack with flexible caulk, and leave it alone.  As far as I know the boat is now 20 years old and it's still structurally ok.  The plate and any moisture still in there expands/contracts and the caulk just allows the flexing.

[brackish]

I've done a lot of repair on rotted core material (not on my CP23) and I would strongly recommend you follow the advice relamb has given.  I don't know how many times I've been convinced that the problem was contained to a small area and then found out it was widespread.  You can chase it if you want, but it will be less work to fix it right now.  I think someone did a post on repairing one about a year or so ago.  I'll see if I can find it.

Looked, couldn't find it, however I think it was a link to a photobucket page put up by MSS which must have been taken down.

[relamb]

Here's one old post, but not the one I recall.  http://cpyoa.geekworkshosting.com/forum/index.php?topic=4012.0.  The one I recall I think the person used a router and set the bit depth to route out all of the wood, working from the top., but leaving the edges of the raised portion.  Then filled the hole with new core and resin and glassed over the top.  That would work perfectly fine, although in your case I'd route around those pad areas where ( the hatch was fastened??) and clean out under them so I would not have to re-form anything fancy.  I have to say, I'd either take the time to replace the whole thing properly (if you have the time and skills) , or just dig out what you can, seal it up with 4200 or 5200 caulk to keep it from getting worse, and worry about it some other day.  As long as there's a good solid area directly under the mast, it's a cosmetic problem for now, not a structural problem.

[BruceW]

I appreciated reading both your explanation and the other thread, Rick. Also, Brackish, I appreciate your recommendation, too. I'm getting advice from others that matches Rick's  latest one about if the wood is solid where the mast connects, then the issues are cosmetic v structural; also, I think preventing further damage goes into it.

I'll be considering what to do over the next couple of weeks, since it's rainy in NC this week, maybe forever, and I'll be on family vacation the following week. Once I get to mid-August, if August is still acting like April with the showers, I'll think of hauling out, lowering the mast, and putting an upside down tub over the whole mast step area so I can leave it untaped and get as much air flow as possible. If I get hot air, dry air, etc, I'll like to then decide on how to close it up, what to fill with.

Bruce

[skip1930]

Put a layer of 3M-5200 slow set under the tabernacle and bolt her back down.

After all that 'smag' on the step is fixed below the tabernacle.

skip.

[BruceW]

Skip,

I'll probably also do that;my first issue is the area to which the tabernacle bolts. I have some filling to do once I dry it out. I'm hoping to get down there Sunday if the weather is good, and stick around a couple of days to make some progress.