The
Brits used buoyant thermal suits and you will need some controlled buoyancy to
get up to the surface during an emergency ascent. Being slightly
negative and with lots of drag added from clothing it will probably be
impossible to get to the surface without added buoyancy?.you are going nowhere
(and sometimes even sinking) without buoyancy. You want to make this as
simple as you can. You are going to find trying to deal with a plastic
bag impossible in the most stressful emergency situation you will ever deal
with. You want to get to the surface as fast as you can?submariners
practicing escapes shoot out of the water up to their knees. You will
flare your body out on the ascent by outstretching your arms and bending your
head back, this opens your airway and allows you to
HO-HO-HO.
Keep
the solution simple using as little equipment possible otherwise you are task
overloaded and will screw up. You are correct in noting that if you feel
the pressure in your lungs, it is probably too late. You will have a
pneumothorax which can lead to an embolism.
Respectfully,
Jay
From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Alan
James
Sent: Tuesday, August 04, 2009 9:23 PM
To:
personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] escape
from sub
Thanks for the
comments guys,
No Frank, I don't
buy the stuff in cartons. ( Note that the email was addressed to the psub
wine-os)
At 300ft an
average full lung volume of 6 liters will expand to 60 liters by the time you
hit the surface but only to 8.5
at the 200ft mark
& then by another 6.5 liters to the 100ft mark. Maybe if you ho-ho-hoed
too much in the first 200ft
you could run
yourself low on air. If you were concerned about this & held back you risk
an embolism, they say that
when you can feel
your lungs expanding too much its too late.
If you had a
small air supply to rely on as back up it may encourage more exhailing &
make the trip safer.
With regard to
floatation; Most people are pretty well neutrally bouyant, some are negative.
If you were comming up
from 300ft totally
frozen & without bouyancy or fins wouldn't it require the same effort as
to swim horizontally underwater
for that distance
fully clothed? Did the "Brits" mentioned have floatation? If 3 liters was an
overkill & took you up too fast,
maybe 1 liter would
have some benefit. With a plasticbag & the valve open you could always
squeeze air out or let it go.
It wouldn't be any
more complex than operating a BCD.
When you hit the
surface you'd have floatation. Nice if you came up successfully from 300ft
& there was no boat about
Am a scuba diver of
20+ years but have never done an emergency accent from any great depth so I'm
only hypothesising.
Thanks Dean thats
encouraging will have a go.