[Default] Thus spake Greg Mossman <mossman@qnet.com>:

<snip>

"Aren't you afraid of the sharks?" "Oh hell yeah, we keep as far away
as possible" (while looking at the shots I have of a bull, althoug at
a respectful distance)

DM at Scuba Club was the same way with us the first day, then just
said "find me when you done, right?"  And got pissed when he ran out
of air before I did.

On Jan 28, 3:36 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:

But that's my excuse, not yours yet.  I'm perfectly comfortable in the
water and have excellent breathing and finning technique after 600+
dives, but occasionally need to shut little people down because they
think they're so "good" on air.  You, however, still have to get over
the hump.  Somewhere around 25-50 dives or more, but in almost all
cases less than 100, divers "learn" to breathe properly underwater.
Your air consumption will drop dramatically no matter your size, and
you can start to use breathing "tricks" when appropriate, such as
using your inhalation/exhalation to change your depth, or holding your
breath (gasp, no!) at appropriate times in order to maintain exact
depth (necessary for taking better photos).

Make sure you keep that to yourself, telling everyone else how scary
it is.  We don't want it getting too crowded underwater :)

Uh, neither.  Better to hold position (swim against, if not too strong
and most surge-induced such oscillation currents rarely are), then fin
lightly when it's in your favor (unless you need the exercise and want
to go REAL fast, but then you miss a lot of stuff).  That's from the
aspect of a slow-going diver who needs time to search for critters and
take their pictures.  Obviously if you're a Navy Seal intent on
placing some explosives according to a narrow time frame, then swim
your a.s off no matter what, but they probably cover that in training.

There is nothing more frustrating to me underwater than some dive op
where the DM/guide motions me to "hurry up".  When that happens in a
place like Cozumel with its strong currents and drift diving, I simply
slow down until the DM disppears from sight, then enjoy the rest of
the dive at my pace.  Us big guys have the advantage over little
Cozumelian DM's - simply increase resistance by putting maximum
surface area against the current, i.e. stand up straight.  Ducking
behind coral bommies to escape the current helps with the especially
pernicious DMs.  (Actually, camera failure underwater is even more
frustrating; better to have a working camera underwater following a
fast DM, then to be carrying a worthless piece of hardware at your own
pace.)

It makes sense to me.

I can't say I'm at all athletic nor optimally fit (and I am carrying a
few more pounds than I like), though I've been a swimmer all my life.
Scuba's a recent thing and I hope to dive many times.  It's a very
serene and beautiful thing.

Question: when swimming against an oscillating current (reef with
surges), is it better to let the current push you back and then swim
strongly when it ebbs, or better to hold position (swim against) and
then let it carry you w/o effort on the ebb?

On Jan 28, 2:24 pm, Ecnerwal
<MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote:

"At rest, we breathe approximately 15 times per minute, with a volume
of around 0.5 litres (producing a ‘minute ventilation’ of 7.5 litres
per minute [15 x 0.5]). The volume of each breath (tidal volume)
depends on body size and metabolic rate (bigger people have larger
lungs and take larger breaths, they also require more energy and
oxygen to support their metabolism).

"During heavy exercise, breathing frequency rises to around 40 to 50
breaths per minute. In ‘the man in the street’, tidal volume rises to
around 3 to 4 litres (minute ventilation = 120 to 160 litres per
minute), but in Olympic class male endurance athletes, tidal volume
can be over 5 litres, resulting in minute ventilations of 250 to 300
litres per minute."

http://ironman.com/training/sponsors/the-first-of-a-series-of-articles-from-powe
rbreathe-focuses-on-breathing-issues-in-swimming-cycling

So, being larger does make one "suck up" more air.  Surprisingly,
those with better fitness levels will have a higher tidal volume and
therefore "suck up" more air when exercising (i.e. kicking against
current) than unfit persons.  Therefore, the highly fit large person
will, on average, suck down a tank much faster than a little couch
potato.  (Or at least that's what I always tell the little couch
potatoes when they brag about having so much air left after a dive
when I've run my gauge near empty.)

I don't do doubles, but few who do seem to mix and match. A pony bottle
(30-40 cubic foot bottle carried auxiliary) is more easily switched out,
but still has most of the extra cost (2 complete regulators).

Doubles and the associated hardware are a lot of money which you could
better spend on going places and diving more. If you are going to buy
tanks you can buy single tanks with larger capacity (100 or 120 cubic
feet instead of the 77 in a typical "80"), but the main thing you need
is more time underwater, perhaps more thermal insulation - a thicker
and/or better fitting suit, perhaps a hood. Being cold burns air. So
does fiddling with a leaky mask.

Being large does not inherently make you suck a lot of air. Being
inefficient does, but efficiency and actual calm takes time. You can get
all bound up in a cycle of trying to be calm (as a deliberate, thunk
act) and not be calm at all because of it. More time diving is the cure.

If you are still burning air like mad at 100 dives, then you might be at
a reasonable point to consider tech hardware (which doubles are) as a
solution. Twelve is a bit early to jump on that, IMHO.

I just got my PADI OW, and added a night, wreck and deep (110') dives,
and others for a total of 12 dives.  (San Andres, Columbia).

My key issue is that I'm 6'2" and broad/deep chested and go through air
like crazy even when I do my level best to be slow and calm.  For my
deep dive, the instructor dragged down an extra bottle/regulator set.
When I got to 600 psi, I took and carried the extra under one arm for
the rest of the dive... not how I'd like to operate in the future.
(Even on a shallower off the rocks dive, I ended up going to my SO (who
is thin) and using her air for nearly 10 minutes before going to the
surface on my own air - 200 psi left - She had 1300 left even with me
stealing her air).  On another dive, there I was at 20 ft with 0 air
left, I could suck in a few last breaths as I slowly made my way up.

Now starting to look at buying gear (all I have are fins, mask and
snorkel, though my 30 year old mask needs replacing, leaks too much
water during dives).

I've found a BCD that takes one or two tanks, so I assume their are
regulars with a cross manifold? (whatever it's called).  Can this be
'mix and match'?  eg: dive with 1 or 2 bottles as needed?