beam floatation

I have an aluminium (mast) section which is going to be chopped up for akas on my 20' cat. How can I add flotation to it? 2-part pouring foam? Same question for the hulls as well, though I might just stuff some white, large-grain cheap and superligt foam in there, don't think it will absorb any water.

 

Foam

Hello Sigurd,

Some people only put the two part foam in the ends as long as there are no holes in the mast section. The use of foam in hulls is a little frowned upon in wooden boats because of ventilation problems. I would be happier just making little bulkheads in the hulls to make watertight bulkheads. These certainly won't add much weight - do it out of 4mm ply or light foam and glass and help stiffen the hull.

cheers

Phil Thompson

 

Thanks. Not sure whether I am going to have holes in the beams yet. I guess I could patch the existing small holes with epoxy?

The tornado already has lots of woven glass bulkheads, but there are holes through them along the keel, and in the center of them (15cm dia). I could plug these but I don't want any enclosed volumes which could be filled with water if there was a leak somewhere.
But there is a hatch abaft the aft beam, in front of it, and in front of the fore beam; so I could have two waterproof bulkheads, so that all three compartments could be accessed.
I don't think there is any wood in it. There appears to be some sort of red foam in the skin, and woven glass EDIT: on both sides. The deck is thicker and I am not sure of what it is made of, but it is not wood I think. close to the beam grooves, where I have cut through, it looks like 0.5mm gelcoat, 1mm glass, 1mm carbon, 3mm yellow epoxy, 1mm glass. Not sure about the epoxy, that seems very odd - But I can't find pores or fibers in this layer. The openings are so small I can't view the whole insides; need to find a mirror. There is some "isopor" (the large-grain white stuff I was talking about) in the bilge of the bows - covered by some very thin glass layer.