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This is my first time on techdiver. I work in Manchester University in
England. I have had about 240 aqualung dives and a few oxygen rebreather
dives, and 2 dives with the old heavy hardhat kit. I am a computer programmer
and users' query answerer, and I am in charge of a room with 16 public use
PC's and a graphplotter and 2 Epson printers in. At the end of April 1994 I
had 18 aqualung dives in 6 days in the Red Sea from a liveaboard ship sailing
from Hurghada to Sharm el Sheikh (Egypt). Sharm el Sheikh is a fair-sized and
growing resort town with many scuba diving centres and its own airport.
I apologize if any of these points hereinunder have been thoroughly argued
and discussed before.
(0) About how many people are subscribed to techdiver?
(1) How do I unsubscribe temporarily from techdiver, if I am going away for
a few days and I don't want my email mailbox to get overfilled?
(2) `aquaCorps' periodical often uses the abbreviation 'C2' or `C squared'
for `closed circuit'. How usual is this abbreviation elsewhere?
P.S. I take it that `E = m c squared' = "<E>fficiency/<E>conomy comes
from
a <m>ixture <c>losed <c>ircuit set, in these modern days." or the
like. :-)
(3) Plans to build dive computers (`bendmeters') into c2 scuba. I disagree
with this, but the computer should be easily detachable, as it may happen
that:-
(a) The same set is used by different divers, whether a long-duration set is
used for two or more shorter dives rather than for one long dive, or whether
the set is refilled and reused and each diver does not necessarily get the
same set out of several similar sets for his next dive.
(b) The same diver uses different sets (of same or different types) for
successive dives, e.g. a mixture c2 set for a deep dive, then switch to an
oxygen c2 set to decompress on because someone else needs the mixture c2 set
for deep diving; or a mixture c2 set dive, then an aqualung (= open-circuit
scuba) dive, then a dive with a short-duration light oxygen c2 because he
needs to get into small places or be light and agile or have to keep climbing
out of the water in diving gear.
In both of these cases he needs to keep his dive computer with him through
the changes of scuba. The dive computer should be able to be connected to the
scuba's oxygen proportion sensor etc. In that case, dive computer makers and
c2 scuba makers should standardize computer-to-scuba oxygen sensor connections
to let any make of c2 scuba be used with any make of dive computer. If the
dive computer is used loose (as with an aqualung), it would assume `ordinary
air' unless told otherwise by setting its `which gas used?' setting by its
ordinary controls.
(c) And (since divers are often warned about flying after diving) add the
case of a diver flying back from a diving expedition with his dive computer
built into his c2 in the unpressurized hold and him in the semi-pressurized
cabin. Again after the flight his c2's dive computer would tell untruth,
unless he can detach it and take it in the cabin with him.
(4) A minor email technicality that I am all too aware of after experience
of a language email group. PC characters whose code numbers are over 127, if
sent by email, are often transmitted by emailers (at least in or to or from
countries like England whose natural language does not use accents or umlauts)
as modulo 128 (i.e. divide by 128 and take the remainder, by losing the 128's
bit). Thus the a-umlaut letter in the name `Drager' is PC code 132, and is
often transmitted by emailers as code 4 = control-D, with unpredictable
effects on computer printers etc when matter containing it is printed etc.
And, even without email, some printers etc ignore the 128's bit and treat
a-umlaut as control-D anyway. I know all too well by experience that computer
software and hardware often react badly to unexpected control characters met
in input!
This may affect diving matters if this name occurs in a text mode dive log
downloaded from a dive computer to a PC and later emailed or printed out or
whatever. This particular case would be avoided by spelling the name as
`Draeger' with separate `a' and `e'.
The same goes for any other PC character from code 128 onwards, which
programmers may use for graphical effect or in a language that uses accented
or umlauted letters in matter to be downloaded from a dive computer.
Also, the characters [\]^_ {`}~ often display as accented letters on PC's
etc set up as for use in Scandinavian countries.
(5) With apologies if this has already been discussed, but how near is
anyone to a drug which will block the nervous/etc mechanism that causes oxygen
poisoning (convulsions etc) at depth?
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