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Once again I found deck rot in the deck of my 1978 424. This time its around the stanchion bases on the starboard side. Two stanchions showed crazing around the bases. I had suspected a problem there for some time. the stanchions on either side of the gate could wiggle if you pulled on them. The deck beneath seemed soft. I’ve had minor problems with deck rot in the past having repaired the area around the main-cabin companionway and around the mast hole. Here’s a link to the companionway repair.
http://www.richardcarter.net/boat/deckRot/Last weekend the stanchion repair percolated up to the top of the “fix” list. I removed both stanchions. One is accessed from the locker behind the head sink. The other is from the nav-station and in back of the hanging locker. Neither is easy to reach. The screws from one stanchion were inside the cable race. I had to cut part of the cable race off to gain access to the nuts.
I took a hole-saw and carefully cut a 1.5 inch hole in the top deck layer in the center of each stanchion footprint. The hole provided access to the deck beneath the stanchion. In both cases, the balsa deck beneath was wet. There was evidence of rot around each screw hole, but the rot didn’t extend any great distance, perhaps an inch around each screw hole. I used an allen-wrench in an electric drill to rout out the damaged core and vacuumed up the chips. I routed around the center hole and inside each fastener hole. I then taped the bottom holes and filled each with epoxy. I first inserted some fiberglass mat in the deck, not as much as I would have wished but I figured that the deck needed some kind of reinforcement where it had been soft. I injected epoxy using a West caulk tube and taped off the top holes. I used a bit of thickener when mixing the epoxy but still left it runny. The epoxy shrank while setting. I assume that it slowly filled whatever voids had been left in the deck core by my work. This required a second round of fill to compensate for shrinkage. Ideally, you’d want to inject using one hole and allow air to escape from a second hole, filling until all air is removed and epoxy squirts out the vent hole. I wasn’t able to do this because of the large access hole. In retrospect, I should have probably glued a flat wood panel of the large hole and ground it off when done. Since the entire area around the stanchion is now epoxy and not balsa, any future leak will not threaten the deck core.
A quality boat would have a solid deck around each deck fitting. While the 424 is a very nice boat, its not in the same league with a top quality boat. Luckily, this kind of repair is straight-forward. Its a bit messy but no big deal.
Its important that we keep up with deck rot. Although the core material is fairly resistant to rot, serious problems can result if a leak is allowed to persist. Water can be getting into the deck even if there is no evidence of a leak beneath. I suggest that owners inspect their stanchions for softness around each base. Wiggle each stanchion while inspecting the deck. If the base appears to move, you likely have a deck core problem.
Regards
Rich
BlackSheep #47_______________________________________________
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Hi Rich-
Good that you caught it. We have done similar repair on most of the stachions. I find that a coat hanger works well for pulling out the bad balsa core out 10-12 inches from the access hole.
Actually, the top skin is pretty thick. Except in the proximity of the stanchion base, canned insulation foam worked ok to fill the space left.
We also added bases on top of the deck made from dumpster obtained fiberglass about 1/4″ thick about twice the size of the stanchion base to spread the load. Doesn’t look all that great, but so far has kept the bunks dry.
Quent
Clairebuoyant, #132 -
Rich,
Thanks for sharing that info. I probably have similar issues around some
stanchions, but the repair hasn’t “percolated” yet.Tor
Silverheels, P-424 #17
http://www.silverheels.us
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For what it’s worth, I recall that Valiant Yachts, who built very high
quality sailboats in Texas until they went belly-up a couple of years
ago, sandwiched high density structural foam in all the deck areas
intended to handle hardware and stress. The word, “foam,” is misleading.
The material may start out as some kind of liquid foam when it’s
fabricated, but what went into the boats was pretty rigid and very hard.
Seemed like something that would last several lifetimes.Tor
Silverheels, P-424 #17
http://www.silverheels.us
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2 componant polyurethane foam is used to replace marine grade plywood on almost all boats today, especially transoms and runners. It’s a very high density, structural foam, around 30-40 lbs/ cu.ft. density. The foam in a can may fill voids but at 2lbs/cu.ft it will eventually disintegrate under load.
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I wonder if that’s the same stuff. Perhaps, though I never saw them use
the material in liquid form.Thanks,
Tor
Silverheels, P-424 #17
http://www.silverheels.us
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Quent,
I know you can buy panels of the stuff in various densities. It’s even
available in pre-cubed slabs for flexibility to fit contoured shapes. If
you need really expert advice, you could ask our local ‘glass-master
down here, Jerry at . Tell him I recommended
him. The guy really knows fiberglassing. (He’s repairing a 3′ crack in
the bottom of Silverheels’ keel. I wouldn’t trust anyone else to do it.)Tor
Silverheels, P-424 #17
http://www.silverheels.us
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You can not pour the liquid yourself. You need mixing eqiupment that is unavailable in the field. Tor is correct in recommending buying panels which you can cut to size and then glassing them. I see no point doing that on a deck..just use glass mat and resin. Some boat makers used balsa to save weight.
The balsa often got saturated from leaks…and was a cause for delamination too. I’ve seen a person drill small holes in the deck and inject resin with hardener and hope for the best in terms of getting adhesion and filling voids.________________________________
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I’ll have to say that filling the void after the fact is very difficult. It can be difficult to reliably tape-off the underside holes for a number of reasons. The holes can be obstructed by the cable race, wiring, or cloth covering and reaching the holes can be difficult. If the holes aren’t well sealed, any epoxy used to fill the holes can run out the bottom. Its best to plan on this and lay in a tarp underneath just in case. Since the deck is canted, epoxy tends to run down to the lower side of the deck. This can evacuate the uphill part of the core. Even if no epoxy runs out of the core, air trapped during the pour will find its way uphill. Plan on a second pour to refill the two uphill holes.
I added some thickener in the epoxy when mixing. You can’t add too much because you want the stuff to run into the deck void. I also inserted some cut fiberglass to add strength. I covered the top deck holes with tape after pouring. Even with this precaution some epoxy oozed out and messed the deck. I subsequently ran a belt-sander over the area to smooth out the repair and clear up any runs. Since my deck is painted with textured paint anyway this wasn’t a big deal. If you want to prevent drips from staining your deck, I advise covering the adjoining area with tape before pouring anything.
One fastener failed during removal from crevice corrosion. All were suspect and were replaced. I used fender washers under the deck. A large aluminum plate would have been preferred, but it was hard to reach the underside of the deck. I would have found installing such a plate to be difficult. The fender washers will spread the load.
Pearson originally used rubber gaskets under the stanchions during installation. I cut new gaskets using a 1/4″ hole punch for the fastener holes. I also laid in a bit of polysulfied caulk under the gasket to insure a watertight seal. The theory is that when torque the nuts, it squeezes the gasket which seals around the fastener holes. Since the fasteners are full length threaded, water would find its way down the threads unless caulk is used.
During winter layup, water will collect at the low edge of the deck and freeze. This will happen even if the boat is covered. Over a period of weeks, a thick layer of ice can accumulate around the stanchion bases. If any water leaks under the bases, it will eventually pull the stanchions out of the deck. It can also build-up around the deck drains and clog them. This can crack the deck and through-hull fittings. I keep an eye on this over the winter, occasionally laying in some rock-salt to eliminate the ice.
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Rich, you have done the best possible for a difficult job. The freeze thaw cycles makes having any leaks even more of a problem. I’ve been keeping my boat in the Caribbean all these years of ownership…my problem is UV…a different enemy than ice.
Rather than adding thickner, I adjust the hardener level to so as to maximize flow from low viscosity, but have the epoxy start to harden and therefore thicken as it raches the pour hole, thereby improving my chances of making all the air escape.
Joe,
Half Moon________________________________
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For a polyester resin using more hardner (MEKP) to get it to kick faster is ok but with epoxy changing ratios can cause all sorts of messes from never curing to brittle set. Â For faster sets with epoxy, instead use faster acting hardner.
Sent from my Android phone with a spell checker programmed to entertain you.
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Quent,
Foam in a can was designed to be used as a weather barrier, an insulation material that can seal small gaps around windows and doors, for example. It’s a closed cell urethane foam, so being closed cell it is able to float and not absorb water, unlike an open cell foam such as a sponge. So, like your flotation ring, it will do a pretty good job of not absorbing water, but under flexing, those cells can fracture and then, if under constant exposure to water, it will start to absorb. If UV light and ozone can reach it, it will also disintegrate over time. So flotation devices are always covered with a skin.
If your application is not under load/flexing, and it is well encapsulated, this product can do the job of filling a void quite well. As it expands 30:1 it’s volume, it flows into nooks that may be hard to reach otherwise..I can see some benefit in that, though if the area to be filled is quite tight, the foam may collapse from the shear, especially if air cannot escape as the foam expands and the cells are still weak. So, success is also void shape dependant.
Otherwise, use a good silicone sealant caulk.
Joe,
Half Moon________________________________
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The bases have four 1/4″ screws. When they get tightened, you don’t want them to crush the deck. I don’t think that spray foam would be a good filler in this application. You really don’t need any strength in the deck filler used to repair a rotted core. There are probably other materials that could be used to fill the deck, but I have a pair of West jugs on my bench. I see no reason to experiment with alternatives. I stuffed some fiberglass mat in there. A chunk of unreinforced epoxy is brittle and can crack if flexed. In theory, the deck wouldn’t flex but you can’t be too careful. Around the stanchions you want something that won’t shrink when compressed.
Rich
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I once saw that expanding foam used to seal a leaky hull-to-deck joint.
The owner had shot it up into the joint area from inside the boat,
somewhat hurriedly because a hurricane was approaching the area. The
foam expanded more than he expected, resulting in ugly yellowish blobs
protruding around sections of the interior, difficult or impossible to
remove to do the job right the second time. The boat was for sale. No
one was buying.Tor
Silverheels, P-424 #17
http://www.silverheels.us
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I once saw that expanding foam used to seal a leaky hull-to-deck joint.
The owner had shot it up into the joint area from inside the boat,
somewhat hurriedly because a hurricane was approaching the area. The
foam expanded more than he expected, resulting in ugly yellowish blobs
protruding around sections of the interior, difficult or impossible to
remove to do the job right the second time. The boat was for sale. No
one was buying.Tor
Silverheels, P-424 #17
http://www.silverheels.us
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Guys, the problem, in my opinion, is that water gets into the deck core around the lifeline bases then sits along the outside edge of the deck eventually degrading the balsa core. Yes, strong core replacement is necessary under the lifeline bases. I use epoxy with high density filler there. The rest of the voids need to be filled so that water cannot collect in the future. My experience with canned foam has been good. I extend the straw with copper tube to fill from the back, and with a little care, there have been no foam overruns.
The only problem I’ve found is that the cured foam, for some reason I don’t understand, fools my moisture meter into thinking the deck is wet.
Tor, sounds like the guy who you heard about could ruin a boat with any choice of material.
Silicon caulk won’t cure unless it is exposed to the air. I would be reluctant to use it inside the deck.
Many boats, Pearsons included, with balsa core decks were built with open seams in the core. Water gets in and eventually finds its way to the lowest area of the deck. Here in the north, it freezes and does damage, or finds its way into the boat.
Quent -
@quent wrote:
Anyone have experience replacing core with high density foam? I’d like to do that in the cockpit, but I’m worried about the expansion pressure distorting a large flat surface.
QuentCoosaboard is the product of choice. It comes in a variety of densities and thicknesses.
Use a Fein saw to cut along the non-skid border. Peel the top layer of glass off CAREFULLY. Dig out wet core to inner layer of glass. Cut Coosa to fill void and epoxy in place using a vacuum bag. Place the old skin back in place and bag it as well. Structural repair complete.Any areas that will have hardware installed should get an FRP plug instead of Coosa.
Common repair on the 30+ age group. $400 per square foot. Cosmetic is extra.
Chuck
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