RE: [PSUBS-MAILIST] riding the bubble

["Brian Cox" <ojaivalleybeefarm@dslextreme.com>]

Sean,
        Ya , I've thought about doing that.  It would be a lot of extra work
and expense.  My main drawback in having air in those pockets is that in
shallow depths the expansion of the bubbles would speed up my accent if I
had injected additional air at depth.  If I expell all the air from that
chamber on my initial decent then the only thing I have to worry about would
be the loss of buoyancy as I decend from the shrinking bubbles.  This would
be most pronounced in the first 60 ft .  I will have hard ballast to
compesate for neutral buoyancy.  As I accend from depth I guess I would need
to play with the hard ballast air.

Brian


-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]On Behalf Of Sean T.
Stevenson
Sent: Saturday, February 14, 2009 7:51 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] riding the bubble


As an alternative to putting holes in the webs, you could use some sort
of filler (syntactic foam?) to create a rounded or otherwise sculpted
upper surface which would not serve as an air trap.

-Sean


Brian Cox wrote:
>    In my incredibly large ballast / support structure,  the inside is made
> up of ribs which are a part of the ferro-cement form and which give the
> thing more over-all strenght.  I've been fretting about this aspect of the
> internal shape of this area because at the top the ribs are a place where
> pockets of air can't freely slide out to where the vent valves will be (
> I'll have a vent on each side) .  So to eleviate this problem I was going
to
> put small 1" holes at the top of each rib ( you can see the plugs at the
top
> of the ribs in the photo).  But now, in lew of the dissusion on the bubble
> riding factor, I'm thinking that that may not be nessesary.  For one thing
I
> don't like the idea of a hole right there because it will weaken the rib
at
> that point, though I think there is enough steel to handle a hole at that
> point.
>
>
> http://www.frappr.com/?a=viewphoto&id=759383&pid=10308219
>
>
> Brian
>




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