Re: A Simpler Sub

[David Buchner <Buchner@wcta.net>]

>A blower won't do the job for you because the design you mention is ambient
>pressure.  At even a few feet of depth, the blower will not be able to
>overcome ambient pressure and your  "canopy" will flood.  The SportSub was
>able to use a blower because it is basically a 1 atm design with submergence
>measured in inches.

Oh. Duh. I should have realized that. I *would* have realized that, as soon
as I thought about it a bit more. Before I built it and got to "a few feet
of depth." Honest. Really.

It would just make a tube going straight to the surface, to allow the air
to excape from the cabin as it submerged and water pushed up from the
bottom.

A blower would work at the surface, though, to change the air after a dive.
As long as the buoyancy of the air in the cabin "bubble" wasn't being
relied on to keep the boat from sinking (ie, ballast tanks big enough).

By the way: The SportSub info on their web site says something about it
being necessary to lift an ambient-pressure sub out of the water at the end
of a day's use. Huh? Do they mean just so the stale, stinky air gets
replaced with totally new, preventing buildup of anything? Or are they
worried that beavers and otters might make a home of it if it's left
floating, or what?

David
buchner@wcta.net
Osage, Minnesota (that's a state in the USA)