Solid Glass Multihull

[Schmacko]

Just as an aside I decided to test the flamability of resin infused foam cored laminate :
With laminate intact....1.2mm thick 450 d/bias glass layer burnt slowly while foam core burnt and disintegrated rapidly, fumes were extremely toxic and definately unbearable.
Separate laminate....outer glass layer was flame self sustaining and fumes were barely tolerable whilst foam was self extinguishing but the fumes were intolerable.
The foam emitted more than 4 times the smoke/fumes than the outer glass layer.

Summary is if your boat is on fire get off or die as before you get near the flames you will be overcome by fumes....if you have breathing aparatus get off or die as you will not have enough time to don the equipment before being overcome by the fumes.

Before doing this experiment I would have tried to fight the fire but not now.

[Factor]

Originally Posted by neilpride

Poly is still a fine resin to make boats ,with a good barrier coat can last forever with no osmosis or delam isues, most of the production boats today still use poly for the hulls with the diference of a last good barrier coat of vinylester or epoxy for osmosis protection, but sometimes even with the vinylester blister show up, FP are a example...

As I understand it the FP issues were all Polyester boats

[cwjohm]

I tried to set my cored hull alight but the match went out when it hit the water.

[toddedger]

Boat Smith says "a J29 has a 2100 lb lead keel. NO WAY is there enough foam in the core to provide positive buoyancy."

Well, Boat Smith
the specific weight of water is 1 cu ft/62.4 lb = 0.016 cu ft will just float one pound.

2100 lb x o.o16 cu ft = 33.6 cu ft

Now picture a box of balsa core 3.36' wide x 10' long x 1 foot high. That would be 16 sheets of 3/4 balsa 10' x 3.36' wide. Lets cut that in half for one side of the boat, and divide x 3 for the rough length of the boat. That would give us 2.6 sheets or an average length of 8.95' to run from the hull center to the center of the deck. Maybe a bit high but don't forget to core the cockpit and transom.

My point is 33.6 cu ft of core buoyancy for a J-29 is not that far off. Also remember that lead keel will not weigh a full 2100 # in the water. The skins on the layup are only about 1/8 thick, and are so dry of resin that there is additional air trapped in the laminate between the core and the skin. Add in the buoyancy of the bulkheads, floor boards, cushions, empty head and water tanks, and the engine is only a one cylinder yamarhammer.

In race trim with out any extra gear but about 8 life jackets, the J-29 sank all the way down but stopped at the coach roof.

YES WAY Boat Smith, I was just as surprised as you, but it really happened.