Last fall, I noticed some dry rot around the carriage bolts that fasten the bronze winch pad to the cockpit coaming on Shaula (hull 59, 1981). The honduras mahogany coamings had been epoxied sealed, primed and painted for about 15 yrs ago. I had never pulled these bolts, so their bedding was done by SLM in 1981.
Removing the bolts wasn?t easy because the nuts were corroded on, and of course the square subhead of the bolts wouldn?t grip the rotten wood. I decided to use an extractor (easy-out) to hold the head while I used a socket wrench on the nut. A big crescent wrench worked better than vise-grips to keep the square end of the extractor from turning. Once the carriage bolts were removed, the hex head bolts holding the winch pad to the deck were easily removed.
Although urethane or polysulfide bedding compound had been used to seal the pad to the deck, Dolphinite was used to bed the pad to the coaming. It had obviously dried up over the decades and allowed water access to the wood.
The rest of the job was more straight-forward. I filled the bolt holes with epoxy filler, redrilled the holes, reinstalled the pad using Boatlife bedding compound, and filled the small holes in the bolt heads with epoxy filler. Finally I used epoxy sealer and primer on the wood coaming where needed, sanded it all, and put on the enamel finish coats. Seattle?s October weather has frequent days of rain, so keeping the wood dry during the job was a challenge.
I suspect this problem is fairly common in older BCC?s. I wonder how others have solved this problem? A friend suggested hack sawing a slot in the bolt head, but I thought that would probably gouge up the surrounding wood.
Dan Shaula
Ahoy Dan , I have always found it difficult to sand the coaming at the juncture of the wood to the deck gel-coat, especially behind the bronze winch mount .
The wood, is often black in color at that joint.
So , what would be a good solution , to add in a reserve of neglect to our varnishing of the cockpit coamings ?
My first choice would be to unscrew the coaming from the cabin sides and below deck , cut 1/4" off that wood joint area, and replace that with a bronze or copper 1/4" thick strip and bed that under the coaming .
This would allow a "sand - down - to - area " , and thus raise the Mahog off the gelcoat . A heap more easy to mask-tape to, without the varnish creaping under the tape , because of the non-skid gelcoat pattern, on deck .
Of course I am in process of going All Teak Topside wood , but this coaming modification, is a bit far down the project list .
More at the top of the list is to replace the propane Mahog deck boxes with Teak wood boxes .
Does anyone else have suggestions ?
Hi Doug,
As you can see from the pics, I have gone the non-varnish route. However, I still have to do some coaming sanding, although not nearly as often or as extensive. The green 3M masking tape I used next to the wood did a very good job of stopping creep. It’s expensive, but worth it as it’s MUCH stronger tape, with a stronger adhesive than the standard blue 3M variety. I try not to stretch the tape as I’m putting it down on non-skid, and use shorter pieces if there’s a curve involved. I press it down very firmly so it’s stuck to all the ups and downs of the non-skid pattern. Sandpaper doesn’t chew up the green tape as much either.
I didn’t have a problem with epoxy sealer (very thin) running under the tape, although I did try to keep the tape wiped off with a bit of paper towel and the sealer kicked off fairly quickly. I used West epoxy for the original sealing 15 or so yrs ago. The solvents in epoxy especially, but also in paint and varnish do seem to dissolve the tape adhesive, especially with the blue tape. I used a sharp knife, run along the wood to tape edge, before pulling the tape off.
I’m amazed at how dinged up the cockpit coamings get in a few years–it’s a mystery! Have you sealed your mahogany with an epoxy sealer? I guess the black wood you get at the bottom means that water is getting under the varnish at the bottom of the wood, doesn’t it? Our varnished port coaming had about 3 inches of black after sailing back to Seattle from Hawaii in 1985. There was no drain in the middle of the coaming, and after being close hauled on starboard tack in the trades for a week or so, there was black below that 3 inch waterline! I mentioned the problem to Sam and I think a scupper in the middle (in addition to the one at the forward end) became standard. Oh yeah, I just remembered, the varnished port bulwarks were very black also! Ugly!
I’ve used the (relatively) non-toxic type paint stripper on paint and varnish with good results. It’s slow, but doesn’t seem to effect the epoxy underlayer, unlike the fast acting stuff.
Dan Shaula (hull 59, 1981)
Hi Dan , Those are v good tips , thanks for sharing them .
I have had other wood degradation issues with the use of silicon bronze fasteners in mahog .
Not only like the problems you had with those cariage bolts in the cockpit coamings , but also in the mahog wood deck boxes.
The screws that fasten the piano hinge and that overcenter clamp down latch , have turned the mohog wood soft and allows the fasteners to be withdrawn by finger pulling pressure them straight out, ouch !
I would guess that I could use “Star Board” under layment to bed the mahog wood on, instead of copper or bronze, or even a built up dam of cabosil and epoxy, would work better than 5200 or Dolfinite .
