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Hi, Hugo . . . thanks for the observations.
You bring up some good points, most of which I hope to address
here.
I
don't think that a bilge pump has enough power to pump against the head pressure
at depth, and if they do your flow capacity would be greatly
diminished.
Assuming ambient
pressure, I'm not sure what the role of head plays. A tiny bilge pump
(ideal for a VBT) moving 450 gph is recommended for discharge up to 2 metres in
height.
If your regulator fails, you will not be able to
pump water out..
I intend to avoid this particular
problem by tapping into the cockpit (i.e.: ambient
air) with a passage of some sort. Magical Child will have a bank of 5
regulators acting in unison (mainly to provide emergency air flow during an
uncontrolled descent). There will be built-in redundency with all
these regs.
In addition, because the VBT will
have a line connected to the ambient air I can use the pony
(bail-out) bottle in the cockpit to vent the VBT by depressing the exhaust
button on the reg straight into the cockpit. That'll force water out of
the VBT through the interconnecting passage.
In essence, all that will be
happening is that water or air will be allowed into the cockpit
itself, but behind a bulkhead to keep us dry.
Also most bilge pump housings are made
of plastic and the motor housings would implode and flood under ambient
pressure as you descend.
I'm hoping the Rule or Jabsco pumps
will have sufficient thickness in the motor housing wall to accomodate a
compensating line to the cockpit manifold. If not I'll have to build some
up with metal and epoxy.
the safety of the human lives in the
submersible as the primary concern.
I agree
totally. That's why I decided to build an ambient sub.
It truly is a
submersible boat and not a submarine. Avoided are all the problems
associated with pressure vessels. A strong understanding of underwater
physics and human physiology is critical to a successful
design.
During sea trials
I'll be working with backup divers in good vis, will have only myself and
one big sandbag in the passenger seat, will be testing in less than one
atmosphere of water close to shore, will be wearing my dry suit complete with
pony bottle, mask and snorkel and will be able to egress using the
hatch. In addition, Phil Nuytten offered to use his facility to "tea-bag"
her. So I'll have his somewhat expert opinion and those of his
co-conspirators. All in all not a bad scenario. I just hope they
don't kill themselves laughing.
Rick
Lucertini
Vancouver
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