A new cockpit sole in plywood and epoxy

27 Apr

My last really major fiberglass job is repairing the gaping hole in the cockpit sole:

The sad remains of a once majestically overbuilt cockpit sole

I decided this could be a sort of test-case for the near-magical properties of epoxy. I was really blown away when doing my deck core repair by how easily thickened epoxy can be used to craft a solid surface and I wanted to see how far I could take this.

I started this repair with a few support stringers made from eighty cents’ worth of oak from the recycled lumber store. I cut holes so that the ends of the stringers rested on the cockpit locker bulkheads and then glued them to the bottom of the cockpit sole with plenty of thickened epoxy.

Dry-fitting the stringers

I used a nice thick epoxy fillet
The view from inside the cockpit locker

I then cut a piece of 1/2″ ply to fill the hole, with a little room at the edges for epoxy. FYI ‘I’m leaving room for epoxy’ is a great excuse when your cuts are a tad off! I painted this plywood with plenty of neat epoxy.

With the plywood dry fit I cleaned out as much rotten core as I could and gave everything a light sand.

Unfortunately access underneath the repair involves climbing over the engine in the one spot where my head fits and lying on the side of the engine pan with 6″ of headroom. And that’s before you get to the water tank! Here’s what it looks like from underneath:

That’s about 6″ clearance between the engine and the bottom of the cockpit…

It would be impossible to do any real glasswork up there without cutting holes in the cockpit locker bulkheads but I wanted at least a little glass underneath to contain the epoxy and give a little extra protection from moisture. My solution was to cut pieces of fiberglass cloth to fit around the stringers and down the sides of the bulkheads. I glued them to the bottom of the new plywood sole taking care to wet out only enough fabric to stick them in place. The idea was that this would save me having to work with loose bits of cloth in that tiny space.

Only the clear bits have been wet out, the rest of the glass is still dry

Time to put everything together. While this little bit of glasswork set I cleaned everything with acetone and wet out the area with neat epoxy resin. Next I mixed numerous small batches of slow-hardening resin thickened with a relatively heavy adhesive filler (West System 406) and gooped this all over the place -onto the tops of the stringers, squished into the gap around the hole where about 1/2″ of rotten wood core was removed, and piled on as filler in a couple areas where there was little of the original structure left:

There was little left of the core in this area so I filled the voids with thickened epoxy.

Next up was installing the floor itself. I took my piece of ply and wet out the rest of the glued on fabric. I tried to fold it into itself so that it would all end up down the sides of the stringers. This only sort of worked but after dropping the plywood into place I was able to lift the edges and push the glass down.

Time for the plunge. Equipped with respirator and shower cap I dragged myself over the engine and slapped the wet out fiberglass into place around the stringers and along the edges of the old hole.

The view from underneath

Fortunately my bit of prep work made this go surprisingly quickly and smoothly. A final squeeze about twenty minutes later when everything was good and sticky allowed me to clean up the bits that had fallen down, giving an acceptable finish for the bowels of the boat:

Before calling it a day I ground a light bevel into the edges of the repair to prep for a top layer of glass.

The new sole. Feels rock solid already.

So far we’re at about 10 hours of work, if that. I was very surprised how easy it was to complete this repair with just a few ounces of epoxy and a bit of wood. All that’s left is some fairing and glass on top and then a final cosmetic fairing for the whole area. Between the stringers and the epoxy this new sole should have no problems standing up to the rigors of use just as long as water doesn’t find its way into the ply. Hopefully my generous coats of epoxy and bottom layer of glass will keep things nice and dry for a long time to come.

Oh, and here are a couple links on cockpit sole repair, if you’re facing the problem:

 Dealing with a soggy cockpit sole -Makes a very good point that you really don’t want to be doing this stuff upside down if there is any way to avpoid it! Trust us, it’s terrible.

http://www.raggedsails.com/boatprojects/repairing-soggy-cockpit-sole/Repairing the soggy cockpit sole -A very thorough and neat job, but it looks quite expensive! I was lucky enough to be dealing with a smaller area and no hardware.

This article was syndicated from Safe At Harbour But Meant For The Sea: DIY Sailing with Paul Calder


  1. Whitney Roberts

    Thanks Paul,
    I bought a 1972 Cape Cod Catboat with a spongy cockpit sole. On my back and underneath I cut out the bottom of the sandwich and the deteriorating foam. Based on your experience I will cut out the sole, install stringers and build it back up. It’s too small a space to continue from the under side. Thanks for the clear description of your process.

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