Low tech floatation-2 litre

[JW-Tex]

I recently read an article on Howard Hughes Spruce Goose test flight, the plane was aparantly filled with beach balls to act as emergency floatation, the article indicated this was atypical and the norm for a sea place test was to use ping pong balls. After the test flight the beach balls were given to the spectators.

When I awoke last night to feed my five month old twin boys last night inspiration hit me. Empty two liter coke bottles for under deck floatation instead of foam. How much floatation would get from a 2 litre coke bottle? Would they fit under the deck of a 20 SeaCraft after it is raised 3 inches?

Just a strange idea...

JW