Friends of mine just bought a papertiger, and its got tyre tubes inside its hull. The guy who sold it to them said it helps make it more bouyant.... to me this sounds ridiculous, if anything it would make it very slightly less bouyant because the rubber from the tubes is heavyer than the air it displaces, and then if they are pumped up more than atmodpheric press. then that weighs more too. Have I missed something, or did the last sailor of this fine craft miss the boat???

I think the idea was probably the same reason other cats have blocks of styrofoam inside. Of course the hull would be lighter without the foam, but if the hulls fill with water for any reason, the foam (or inner tubes) keep the boat from sinking to the bottom.

Damon's right

the only way for a closed in hull boat to be MORE boyant than just filled with air is if it was a vacuum.

In that case, the weight needed to reinforce the hulls from the inside would offset any gains from having litterally nothing inside the hulls would produce no net weight savings.

Thats saying, if such a technique exists, which I've never heard of.

Yes, filled with hydrogen, the elliptical hull becomes the most efficient foil with a fineness ratio that approches zero asymptotically from some other number, thereby rendering all handicap systems impotent by canceling gravity and friction but conserving mass and momentum... it's incredible, isn't it?



It's late, and my daughter's hungry again, hence the gibberish. Seriously, you're innertube is indeed jimmied-up positive flotation. Only provides buoyancy once the hull's been removed from the displacement equasion.

Just make sure it`s only air you have inside.
Many years ago a Paper-tiger owner filled his boat with those inflatable bags that came from box-wine (if you don`t know what I`m talking about, they are 5litre plastic bags with a silver foil-type outer surface & a type of tap, like a strong plastic bag mated with a beer-keg.)

A couple of weeks of standing in the sun, the leftover wine in the bags started fermenting nicely, the strong plastic bage started expanding slowly, until the owner came back to the yacht club, only to find his boat had exploded.

Cheers
Steve

Sounds like another one for:

Myth Busters!