Greg, Thanks for that info. Now that is useful. Alludes to a
remark Phil made on effects of narc in getting out of a sub which is good for
blow and go but not much good for 2 or 3 people subs. Does the navy have
a rate of filling to accommodate this? That rate of pressurization would
mean at least 3 minutes. Is there a paper on the effects of cold on
narcosis. What is the effect likely to be? While we can pontificate
on these aspects I don’t think we should dwell on them too long and
concentrate more on release of entanglement items as Vance has pointed
out. As a flying instructor once told me in answer to my question of what
should you do if you get into this situation--- He replied “A good
pilot avoids getting into those situations” Regarding
a wet suit in the event of ------ Is a full 3mm going to be better than a
top half 7mm . Space is a premium. Chs, Hugh From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Greg
Cottrell Maximum recommended safe descent rate for scuba varies depending on
the certifying agency but fall between 70 and 80 fpm. Faster than that
aggravates nitrogen narcosis. It can also cause joint pain and HPNS. Another danger escaping from a sub could be shivering
uncontrollably in cold water. It happened to me once when I was diving with the
FD and it’s something that doesn’t seem dangerous but is when you
literally lose all muscle control. A thick wet suit top would probably be a
good take along item in cold water. Greg
Cottrell Project
Manager http://www.precisionplastics.com P please consider the
environment before printing this email From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Jon Wallace
Hi
all, I've
put some facts & figures together re flooding a K250 at 200 ft. Firstly,
sorry I move between metric & imperial. I was brought up on imperial
then N.Z. moved to metric. The metric system is great for these soughts
of calculations. The
first assumption is that the hull & hatch area displaces 1,100 liters. The
hatch 100 liters & the hull 1000 liters. The
flow figures through a 2" pipe come from table 2 on this link. It was the
best I could find. These
figures are approximations as the flow rate changes all the time. Also I'm not taking
into account how many or how fat the occupants are. To
fill to half way with the 2" valve at 100 psi the water will be coming in
at 384 gallons per minute. It
will fill the 550 liters (132 gallons) in about 20 seconds. The air in the hull
will be compressed to
half its size & will be an equivalent pressure (14.7 psi) as at 33 ft. To
fill the hull from 1/2 to 2/3 the flow pressure will be between 85
psi & 70 psi. About 340 gpm. The
volume to be filled is 183 liters ( 48 gallons ).This will take 8 &1/2
seconds. In terms of internal pressure
you have just gone from 14.7 to 29.2 psi wich is the same as diving from 33 ft
to 66 ft in 8&1/2
seconds. To
fill the hull to 3/4 the pressure will be from 70 to 55 psi about 300 gpm. The
volume to be filled is 92 liters ( 24 gallons ). This will take about 5
seconds. Again this is equivalent
to going down another 33 ft. to 99 ft. Am
being kicked off the computer for the night so will leave it there. But
that is flooding so fast, I'd want to have my hand on the valve as at that rate
you'd blow your
ear drums for sure. It's best to equalize your ears before they start feeling
pain & in this instance
you can't reverse the pressure like while diving, by ascending. These
figures are open for correction. Regards
Alan
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