Not until May.  Mid May.  Over three more months to go.

this discussion and ptII  has been very enlightening - nice discussion
and points.

Now shut down the thread and lets get back to guns, politics, and global
warming!@

Just kidding - Greg when do you leave on your next trip?  I'm going to
Vegas and betting on a volcano eruption or an asteroid strike.  Do you
have any preferences?

Have a good trip!

On Jan 29, 7:52 pm, Ecnerwal
<MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote:

But exhaled air is 78% nitrogen versus the 79% in inhaled air.  With
every breath of recycled air from a snorkel's dead space, you're
actually reducing the percentage of nitrogen inhaled versus inhaling
fresh air.

Duh.

I find it amusing that you accept this as fact, but agree with Greg that
it's "ludicrous"  that there is an effect, small but non-zero, of
rebreathing more of the excess nitrogen which is coming out with the
exhaled CO2 that you are breathing back in. It's exactly the same thing
- a snorkel adds dead space to your airway, increasing the amount of
whatever your breathe out that you breathe right back in - so if you are
offgassing nitrogen, you are breathing in a snorkels-worth of what you
breathed out every time, meaning that what you breathe in is richer in
nitrogen and carbon dioxide than it would be if you did not have a
snorkel in your mouth. That does make offgassing less effective than
unrestricted breathing. It raises the partial pressure of nitrogen in
your lungs.

If you think there is no effect, try adding a 10 foot extension to a
snorkel (stay on dry land) and breathe through it until you pass out.
You'll be passing out from lack of oxygen, but it illustrates the effect
of the tube - the effect of a shorter tube is less, but it's not
nothing. All I said was that it is not quite as effective to snorkel at
the surface as to breathe freely at the surface - not "OMG you can't
possibly do that!" I do it myself sometimes, when the site permits.

Did you not do an ESA from 15 feet on your instruction dives? I missed
doing it on my lake dives due to some confusion about which instructor
was taking which student and I had to do it on my first ocean dive
after a rather long kelp crawl from the boat with the instructor. My
course was combined NAUI/PADI. Fifteen feet only gives you a taste of
what it would be like from 30 or 60 but it's enough to make sure you
understand the principles. We were also taught to keep the regulator
in your mouth just in case you couldn't resist the desire to inhale or
in an actual OOA situation there might be enough left on the way up to
cover the ascent.

This is a bad idea. As a newb I tended to delay putting the regulator
in my mouth to the very last minute too. This can only make you suck
more air on the dive and I have demonstrated it to myself several
times. I pretend the snorkel isn't there. On the surface, swimming out
to a descent line, OK, the snorkel is in. But in that case it's a good
idea to stop at the line and take the snorkel out and rest and recheck
with your buddy. Then put the regulator in your mouth and begin your
descent together. With a snorkel you are getting just a little bit
more CO2 from the spent air in the tube vs. without and this tends to
increase your respiration rate, it's a reflex you have very little
control of. You are also increasing your overall anxiety about the
dive by initially worrying about your air consumption even before the
dive begins and adding to the busy-ness at the surface playing with
regulators and snorkels and which one is appropriate. Sucking water
through a tube because you played games with the descent and then
suppressing coughs while you swap to the regulator is just silly. You
also want to make sure your regulator is in your mouth and properly
seated and breathing correctly before you are suddenly at 3 feet with
no air in your lungs and a tangled rig.

The goal is to be prepared, calm and ready to begin your descent
BEFORE you begin your descent.

Diving is in stages, preparation, donning, entry, descent, trim, swim,
ascent, safety stop, surface, exit. Each has things you need to be
concerned about and focused on in addition to your situational
awareness on your pressure, depth and your buddy. Focus on each stage
and you will be calmer and more competent.

The Zen of diving is confidence in your training and your skills and
to not fight the element you are in but to ride it like the fishes.
When you are calm and not fighting current and not needlessly pushing
your own weight of water your air consumption will decrease
dramatically. I went from 40 minutes of air on a 30 foot dive to 70
minutes according to the computer once I finally became comfortable
and experienced. A one hour+ dive to 35 feet in warm water kissing sea
cucumbers was nothing. Proper trim and buoyancy control help
immensely. Others have commented about how wasteful mask clearing and
equipment problems can be. This goes to preparation. As a snorkeler I
tended to fight the water more, as a scuba diver I have learned to be
'one' with the water. It has given me a deep appreciation of the
beauty and skill of real free divers who can free dive for minutes at
a time.

As a confidence builder with an experienced buddy, preferably a decent
instructor, a 30 foot exercise would be a good idea for a first dive
of the day. Be aware that the reason they do it from 15 feet is to
minimize the risk to you and your instructor because it's essentially
a bounce dive and the ascent is more rapid than recommended.

I have experienced cheap stuff, Apollo Prestige fins, Force fins, and
Apollo Bio fins, I like the Bio fins best. The Prestige fins wobbled
and yawed more and generally worked my ankles more, leading to a
tendency to cramp. Force fins felt lighter but I couldn't get the hang
of them and they seriously sucked on the surface or walking to the
boat gate. The Bio fins seem more stable and I cramp less, I can also
kick slower than my buddy for the same swim speed. I bought the
Prestiges as a beginner, inherited the Force fins, bought the Bios.

Very true.

Well, for a newsgroup there is surprising consensus ;-) on the above
points, so it's sticking...

Not sure where it's so clear.  A lot of people dive in the Gaspe, which
is definitely saltwater, clear and cold.  Though not as cold as les
Escoumins (2'C) which is definitely dry suit country.  You might get
away with a thick wetsuit at Gaspe.  I think.

I will definitely look to dive here to increase my experience.  My SO is
less willing.  I (chubby) did not need a wet suit at Cancun or San
Andres, but she needed one badly (thin).  (After a 15 minute pool
exercise she was shivering w/o a WS).  There are a few dive shops along
my usual routes and when I have time I'll drop in to ask about organized
outings.

I'm looking to buy some used gear as well.  I'd rather learn about what
I like or not from used gear before committing to new.  Feedback from
others helps too - esp. if I can find some divers about my size.

Like I said - well aware and deliberate on my swim back to the boat on a
shallow climb.  That particular dive was to 70 ft.  The instructor did
not practice safety stops except on deep dives (100'+). I know that is
against all prudence, but that's the way they seem to do things there.
The sole time we did a 3 minute stop was on the dive to 110'.

I have no problem with the physics and needing continuous exhalation.
It's "doing it" that intrigues me I suppose.

I visualize my lungs as quite fragile throughout the dive - so that's a
good reminder to exhale all of the time.  Though going over coral/plants
when skimming the bottom I would tend to hang on to the air for a few
seconds until momentum would keep me going up.

No doubt.  But I'm fairly clear on the need to exhale.  (OTOH I'm also
the guy who starts the dive bleeding the BCD while confidently breathing
from my snorkel - at least until I choke on water going down.  So a
clear head and intention is needed.  Visualization.  etc.).

As I said, I intend (too strong a word, perhaps) to do the first one
from 30' and then work my way down on later dives.  It could be that I
do it once and for all at 30' and I'll be content with that.  Sounds
more and more like a plan, actually.

Excellent advice.  While I'm a proficient photographer who usually works
fully manual, I suspect that for diving I'll be as automatic as possible
in the camera.  And I have no stunning ambitions for that photography
(initially) - I'll probably get a P&S with a pressure enclosure.  I know
that's not particularly "photo worthy" but at least for close ups the
colours render well with the flash.  Shots of other people look pretty
lame (like the ones I posted... not my camera).

I'd be more likely to exhale and then pull in a quarter/half breath.
Kinda like shooting.  IAC, photography is not the highest item on the
list by far.  I'm a slow, deliberate, tripod kind of photographer, so
I'd need a different plan under water.

I could probably generate better test data for a pair of strap on
bricks.  That's a cynical remark regarding manufacturer influenced test
data.

People (not targeting you) tend to have a lot of ownership loyalty and
hence after plunking down cash on something, they defend it to
absurdity.  (This applies to cameras, cars, cheese and very soon to your
nearest iPad owner).

Most magazines have turned into gear promos.  And again, I'm not talking
about diving alone.

Are there specifically good scuba gear review websites?

For example, for photography, dpreview.com is spec. exhaustive and does
pretty good testing.  They have their biases, of course, but you sure
learn a lot more about manufacturers offerings than you ever could
perusing magazines or co. literature.

Just a few more comments - what the heck, it's actual scuba, which seems
to have gone missing from rec.scuba since the last time I was reading
it, mostly.

As others have mentioned, and as the instruction material should have
(but they like to dumb it down more and more) snorkeling is not a great
practice for surface intervals. Snorkeling by which you actually mean
free diving is a very bad idea - even surface snorkeling is not quite as
effective at degassing as being on the surface breathing - the length of
the tube makes respiration somewhat inefficient. Also, it does not help
thermal management - even warm water is cold, barring a thermal spring
(and what a sucky dive that was - amusing, but sucky)

Do larger people use slightly more air - yes. Is that your primary air
consumption problem at 12 dives - almost certainly not. The difference
between large and small folk at the same level of experience is much
less than the difference between experienced and inexperienced folk. Was
diving at the beginning of the month, there was a guy on the boat of
similar size and age, shallow water (25-30 feet) 1 hour limit requested
by boat. He seemed to be in pretty good order, but was coming up with
250-300 lbs several minutes before my wife and I were getting out after
the hour with 750-1500 lbs. Coincidentally, those were dives 11 & 12 for
him. He'll get better, and so will you.

Back when there was more discussion of scuba here, there was someone
from your (very) general vicinity with a tagline about the St. Lawrence
being comparatively warm, clear freshwater diving. Certainly people from
this general area do drive 4-5 hours to go diving up there. While you
might be that far yourself, depending which part of Quebec you are from,
it's a good place to go get more time underwater without as much
"opportunity cost" as tropical locations, or the cold murk of lake
thermoclines and the north atlantic. No coral, but there are wrecks and
some wildlife. Probably wait for summer...

If you and your spouse both like to dive, a liveaboard dive boat is a
great way to get a lot of diving in when you do go to a tropical
destination. 5 dives a day is very nice.

If you were aware of your pressure and ran out of air at 20 feet, you
were failing to act appropriately on your awareness. You get away with
that behavior until you don't, and then you get shipped home in a bag.
There certainly wasn't any 3 minute safety stop at 15 feet...

If you ascend from 60 feet, you will have plenty of (too much actually)
air in your lungs, even if you just exhaled - remember that the air in
your lungs will expand as you go up - just keep blowing bubbles. Our sub
guys train for it in a 100 foot deep tank, if I recall correctly. Some
TV show about the training showed their "don't hold your breath, stupid"
training tool - a nearly empty sealed plastic bag released at the bottom
of the tank, which burst somewhere around 20 feet.

You will have to get over a desire to breathe in, however. Some of the
more technical organizations apparently train for using the BC as a
crude rebreather in that instance, but if you are going that route,
you'll want to be sure you disinfect the inside of the BC - our
instructor commented that you could get some great lung infections from
that practice.

Actually practicing free ascents is a considerable DCS risk - limited if
you just go down to 60 feet and immediately ascend - also limited if you
opt to stop at 15 feet rather than take your practice all the way to the
surface.

You might want to leave the camera to your air-sipping wife - even with
100+ camera dives, merely taking the thing causes a noticeable increase
in air consumption for whichever one of us is using it. We've arrived a
policy of just not taking the camera on the first dive of a trip - it's
more task loading when it's not a good idea, since it's usually months
between trips and the first dive is always a bit of a shakedown and
refreshing habits/skills.

While someone else commented that they "*GASP* even hold their breath"
or words to that effect for camera positioning, I will stop breathing,
but not hold my breath - there is a difference, and the difference is
that holding your breath involves stopping up your airway, and not
breathing does not. As such, not breathing does not involve any risk of
lung overpressure injury.

There are better fins than the old things you have, but what fins are
better can be a bit of a religious issue, and probably also depends upon
intended use to an extent. I like the Apollo bio-fins (with the slit),
and they seem to have some decent actual test data supporting better
efficiency.

If you read magazines, Dive Training is the one we've kept up the
subscription to, though you have to ignore the gear press releases,
since they are press releases, not reviews. 11 years ago Rodale's Scuba
Diving had the only actual gear reviews that would EVER say anything
negative about anyone's gear, or do any actual testing, but the rest of
the magazine was crap - once we got our gear bought we dumped the
subscription. No idea what it's like now, or if it's even still in
business.

In 1996 when I was certified, PADI, NAUI and DAN all advised against
snorkeling after or between dives. I don't think that has changed.

The physics makes it NOT a zero sum. While you are not absorbing new
nitrogen on your snorkel dives, you still have more nitrogen in your
tissues than you should have for normal surface pressure. Diving to 20
feet with a nitrogen load from a scuba dive and then a rapid ascent
can get you bent.

You are also not off-gassing as rapidly as the tables are designed or
your computer calculates so your SIT is not what you think it is and
your computer is lying to you on your next dive and not in a good way.
Your nitrogen load is not what the clock time is telling you and you
have no way to calculate what it really is. Granted, the tables and
computers are "conservative" but do you really want to bet your life
or nervous system on the margins?

Unless you have a bottle of water on your snorkel you are also not
re-hydrating during your SIT and dehydration has a strong influence on
your blood chemistry and your off-gassing rate.

Take the swim, stay on the surface, get back in the boat and take your
hydration. Pee on the ascent and avoid the extra swim altogether.

oh.  I would have though it's zero sum since I'm taking "surface air"
with me, not 'pressed.

Now that you bring up my other bad habit...

That I can manage, but I may have PO'd buddies as I signal end-of-dive
earlier than they're ready.

Certainly - not all on the same day, or even consecutive days, either!

On Jan 28, 5:11 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:

Hey, it's Colombia :)  Third-world dive practices often vary from the
first-world agency dictates.  The thirder the world, the scarier the
dive op.

It's also not as safe, now that you're a diver.  Don't forget that
right after the dive, you still have plenty of residual nitrogen left
inside your tissues, just (presumably) not enough to cause any
decompression sickness at a normal rate of offgassing.  However,
repetitive free dives post-scuba have been shown to shake up the
normal offgassing process enough to cause problems.  If you want to
snorkel after a dive, stay on the surface.

No, well-maintained equipment will rarely fail and when/if it does,
most regulators will fail "open", i.e. they'll free-flow instead of
cutting off the air supply.  Free-flows are messy and noisy, but they
won't keep you from breathing normally long enough to maintain a slow
ascent back to the surface when you abort your dive.  However, there
are some regs, a few Poseidons that I can think of and probably some
others, that will fail "closed" and make you wish you stayed within
arm's length of your buddy like they told you in class.

What's statistically more likely, at least according to the
statistics, is inadvertently running out of air.  That's plain
stupidity, since everyone has a gauge (or should be smart enough to
abort when the gauge fails), so those victims don't garner much
sympathy.

Not that I haven't done a few gaugeless dives out of what I considered
"necessity" (i.e., I needed to dive!), but only after assuring myself
that the tank was full, knowing my air consumption intimately,
sticking relatively close to a buddy, and staying shallower than 30'.
Don't try this at home :)

Just keep exhaling as you go, keep the ascent slow, and make sure you
try it at the beginning of a dive day, before you've accumulated too
much nitrogen and a too-rapid ascent becomes a real issue.

You're right of course.  I did mention this to them and said sorry in
the same breath.  They didn't seem too upset.  They didn't "flag" the
bottle either - which makes one wonder.

Excellent point.  That side (west) of the island had very little boat
traffic (east side is very heavy).  But you're right, it would be good
to avoid boats, esp. as I surfaced a good way away from the dive boat.

I'm quite happy to snorkel (been doing that for a long time) when on the
surface.  Actually, the boat captain didn't like me much as after I got
all my gear in the boat, I'd often dive right back in for a snorkel (and
piss call) waiting for the others to arrive.  He liked to have all his
ducks sitting on the bench.  Snorkeling to 20 feet isn't as easy as it
was 20 years ago though...

Opportunity knocked.  It's not that I'm Mr. Ice, but as I was trying to
find the primary at some point I saw the yellow spare down on the clip.
 At some point I said "screw it!" and took that.

I get that.  (On one submersion I was breathing from my snorkel when I
bled the BCD.  That was really rude).  But does equipment "do that"?
eg: just fail in one go?  Are there stats?

On some dive in the future, under well considered conditions, I'd like
to try a one breath assent from 30, then 45 then 60 feet.  There are
more interesting things to do, of course, but that's one for the "try
it" jar.

On Jan 28, 3:30 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:

We're not worried about you, we're worried about the equipment.  When
you eliminate the positive pressure, i.e. no more air, then you allow
backflow of sea water into the regulator's first and second stages and
potentially into the tank itself.  That really pisses off dive ops if
you're using their rental gear.

What doesn't kill you makes you stronger.  Some people swear by the
need to maintain some air at the surface, because they don't like
ocean swells.  But if you're comfortable and don't need to breathe
through a regulator at the surface, you still need to consider the
immediate need to re-descend, especially in areas with boat traffic.
If you surface and a boat is motoring down on you at high speed, your
immediate instinct will be to let the air back out of your BC and
descend quickly.  You'll really be appreciating even a drop of air
left in your tank at that point.

More advanced classes, and certainly tech classes, will actually train
you like that.  It's good that you "trained" yourself, since safety
conscious certification agencies don't like to let the instructors
actually hide stuff from you during open-water training nowadays.

If you're a free diver that can easily hold his/her breath for 5
minutes?  Of course not.  For the rest of us, you'll be fighting an
instinct to breathe, but you'll still have plenty of oxygen.  It's all
in your head.  That said, there's no guarantee that you'll have that
"one breath of air" left.  If your air source conks out right after
exhalation, you're screwed!

I was fully aware of my air state as I had the pressure guage in front
of my face during the climb-swim to the boat.  No panic, worry or
anticipation over it and when it ran out it was no surprise at all.

That's why I was at 20 feet and climbing.  I just leisurely swam
straight up, slower than my bubbles, turning to look for surface
obstacles.  At the surface there was some pressure left for the BCD and
I added to that through the low pressure tube.  The net consequence of
all that was I had to swim a hundred meters to the boat on the surface
and I learned more about what to expect when pressure is low.  I'd
prefer not to do this "regularly" of course, but this was "school" time
in any case.

On one of the instruction dives where I had to recover a lost 2nd stage,
I actually couldn't find it (30 ft).  After trying all the techniques
(rolling all the way right, using my left hand to tilt/lift the tank,
finding the first stage and trying to trace the 2nd ... and failing
(Lord knows why)) finally, without panic I took backup regulator and
used it.  Immediately after that failed attempt, I did it again with no
problem.  Not really sure at all why I couldn't do it the first time.
The instructor said later he was more impressed by that slow process and
then finally resorting to the backup than if I'd actually done it right
in the first place.

This raises a question, though.  Is it feasible to go from 60 feet to
the surface on one breath of air?  That is to say, while continuously
exhaling, slowly, rise right to the surface over a period of one minute?
 Would one feel that they were "out of oxygen?"

(For the sake of this question, let's assume that the dive was no deeper
than 60 feet).

He was very aware of my high rate of consumption and gave me the check
air signal quite a lot until he was satisfied I knew my state (eg: he'd
ask and I'd have a ready reply as I'd recently checked).

To be sure, I've become quite sensitive to status.

I was doing that from about the 4th dive as I realized what an air pig I
am.  Most of the bottles were right at 3k on each dive bud discovered a
couple times they were at 2800 and switched to 3k bottles.

Thx,
Alan

Forgot to address this point in my first reply - you, only you, and
nobody but you are responsible for checking your air before and during
the dive, and making sure that you (and your buddy) come up in time to
have air left. Being out of air at 20 feet doesn't "just happen" (and
where was your buddy, with her octopus and lower air consumption rate?)

If your instructor failed to make you a self-reliant, self-aware diver,
your instructor did you wrong, but since you are certified, it's now
your problem to make yourself self-responsible and self-aware, since
that is what certification is supposed to indicate. This is a common
failing of some (not all) resort-area tropical dive "instructors."

In the minor fiddles department, when you and your buddy board a dive
boat, while you are checking that all of your tanks for the trip have
air and setting up your gear before you leave the dock, note the
pressure in them all, and put the higher-pressure ones on your side of
the area (there's nearly always a little variation in the fills.)

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?