Foam Removal and Floor Re-build
Posted: Tue Jun 09, 2009 2:01 pm
Ever wondered what was under the floor in that triangular space under the front storage area(anchor locker) ?
This is on a 30' Sea Villa, so I'm not sure how similar the larger boats are, but I suspect they must be close.
On my boat there was an old unused oil tank for a diesel heater that I removed and got to thinking about the condition of the floor,etc.
This was a plywood floor, notched to fit between the ribs. Under this was dense yellow foam, probably Urethane. Over time Urethane can absorb water, even though it's 'closed cell'. (Ask someone with an old Boston Whaler). Mine was about 25 percent saturated (and heavy), as it turned out.
I broke out the foam, down to the hull. The foam is fairly tough, but separated from the hull itself quite easily. This was probably installed by the factory, as I found three loose pieces of scrap aluminum embedded in the foam.
The black that is visible in the photos is from the old oil tank seepage that also permeated the foam in places, mixing with water and making a tarry mess in spots.
The newly exposed hull looked fine under the foam, except for a couple of small areas where there was white pasty looking goop that revealed shiny aluminum when scraped away. Luckily this was very localised and I'll repair this with epoxy.
I was debating whether to leave this area empty, after cleaning, epoxy repairs, and final epoxy coating, but decided that would mean having to install a bilge pump to drain off the inevitable rain,etc leakage. The factory drilled small holes with tubes, just at the level of the old floor, that drained off water (well, most of it) into the main bilge.
Some of this water will have been from condensation dripping from under the alloy deck. Tight fitting foam will help this in future.
I decided to re-foam this space with 'pour in place' foam, trimmed level and then sealed with epoxy, and then glassed over with fiberglass cloth (Biax or similar) with epoxy, to create a new floor. If this goes up the side of the hull a couple of inches, it should be pretty watertight. Eventually I would like to spray foam between all the ribs and beams under the deck, but that's another time. I still might glass a hole in the floor at the back and put in a small bilge pump. This could actually exit up to one of the troughs around the access hatch, which have their own drain holes out the side of the hull.
Jay
This is on a 30' Sea Villa, so I'm not sure how similar the larger boats are, but I suspect they must be close.
On my boat there was an old unused oil tank for a diesel heater that I removed and got to thinking about the condition of the floor,etc.
This was a plywood floor, notched to fit between the ribs. Under this was dense yellow foam, probably Urethane. Over time Urethane can absorb water, even though it's 'closed cell'. (Ask someone with an old Boston Whaler). Mine was about 25 percent saturated (and heavy), as it turned out.
I broke out the foam, down to the hull. The foam is fairly tough, but separated from the hull itself quite easily. This was probably installed by the factory, as I found three loose pieces of scrap aluminum embedded in the foam.
The black that is visible in the photos is from the old oil tank seepage that also permeated the foam in places, mixing with water and making a tarry mess in spots.
The newly exposed hull looked fine under the foam, except for a couple of small areas where there was white pasty looking goop that revealed shiny aluminum when scraped away. Luckily this was very localised and I'll repair this with epoxy.
I was debating whether to leave this area empty, after cleaning, epoxy repairs, and final epoxy coating, but decided that would mean having to install a bilge pump to drain off the inevitable rain,etc leakage. The factory drilled small holes with tubes, just at the level of the old floor, that drained off water (well, most of it) into the main bilge.
Some of this water will have been from condensation dripping from under the alloy deck. Tight fitting foam will help this in future.
I decided to re-foam this space with 'pour in place' foam, trimmed level and then sealed with epoxy, and then glassed over with fiberglass cloth (Biax or similar) with epoxy, to create a new floor. If this goes up the side of the hull a couple of inches, it should be pretty watertight. Eventually I would like to spray foam between all the ribs and beams under the deck, but that's another time. I still might glass a hole in the floor at the back and put in a small bilge pump. This could actually exit up to one of the troughs around the access hatch, which have their own drain holes out the side of the hull.
- Foam removal from between beams.
- Loose scrap embedded in foam.
- Corrosion in hull. This is under the area in the top photo that still has the foam in place,
just below the wrecking bar.
Jay
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