500 psi at the boat and the 130' limit.
capt.bill11
on another forum with some one about the history of those limits. And
whether or not they are arbitrary or not. And if they have any real
basis as being safer than say any other number.
So anybody care to refresh my memory on the history of those numbers?
JRE
My opinion:
500 PSI is about 350 PSI usable before breathing gets harder, depending
on the regulator in use. 350 PSI is about 12% of a tank of air in an
3000 PSI tank, a bit over 8 cubic feet for an AL80. As margins go, 8 CF
is a bit thin at 130' (let's say a bit over a minute of moderate
exercise), but it beats "nothing" by a mile and it would probably be
hard to talk recreational divers using singles into greater margins.
I'd rather be more conservative, personally, but I also carry a lot more
gas than the average recreational diver and I don't dive singles without
a 20 CF pony.
Pretty significant narcosis sets in around 140' on air or Nitrox, at
least for me on most days. At least some of the agencies that certify
for Trimix recommend an equivalent narcotic depth of 100' on deep dives.
I'd prefer to limit depth for air or Nitrox to about 150', but if the
dive is complex or long I'd want Trimix or to stay shallower.
Another way to look at this (thanks, Popeye, for your "where are the
bodies?" post a year or two ago) is to observe that those who obey these
limits don't seem to die very often. There is a pretty broad body of
experience that say these rules are "conservative enough," in other
words, in light of current training standards and diving with a buddy.
So while these margins make me nervous for the average recreational
diver who dives once or twice a year, they seem to be working reasonably
well. YMMV...
--
John Eells
Douglas W. "Popeye" Frederick
"JRE" <not...@nowhere.invalid> wrote in message
news:hkqh4k$dva$1...@news.eternal-september.org...
> capt.bill11 wrote:
>> I know it's been discussed before. But I'm getting into a discussion
>> on another forum with some one about the history of those limits. And
>> whether or not they are arbitrary or not. And if they have any real
>> basis as being safer than say any other number.
>>
>> So anybody care to refresh my memory on the history of those numbers?
IIRC, there's a gear related military history significance about the 130 ft
mark- something about older regs' breathing characteristics going to crap at
that depths, and it just became an arbitrary rule-of-thumb.
ESG will be along to explain that coherently.
> My opinion:
>
> 500 PSI is about 350 PSI usable before breathing gets harder, depending on
> the regulator in use. 350 PSI is about 12% of a tank of air in an 3000
> PSI tank, a bit over 8 cubic feet for an AL80. As margins go, 8 CF is a
> bit thin at 130' (let's say a bit over a minute of moderate exercise), but
> it beats "nothing" by a mile and it would probably be hard to talk
> recreational divers using singles into greater margins.
I think that's true.
They gotta set a limit (for me to ignore) somewhere, and 750 or a grand
would be too much.
> I'd rather be more conservative, personally, but I also carry a lot more
> gas than the average recreational diver and I don't dive singles without a
> 20 CF pony.
> Pretty significant narcosis sets in around 140' on air or Nitrox, at least
> for me on most days. At least some of the agencies that certify for
> Trimix recommend an equivalent narcotic depth of 100' on deep dives. I'd
> prefer to limit depth for air or Nitrox to about 150', but if the dive is
> complex or long I'd want Trimix or to stay shallower.
>
> Another way to look at this (thanks, Popeye, for your "where are the
> bodies?" post a year or two ago)
I've put that paradigm to many good uses. :-)
> is to observe that those who obey these limits don't seem to die very
> often. There is a pretty broad body of experience that say these rules
> are "conservative enough," in other words, in light of current training
> standards and diving with a buddy. So while these margins make me nervous
> for the average recreational diver who dives once or twice a year, they
> seem to be working reasonably well. YMMV...
>
> --
> John Eells
--
--
Popeye
"If one does as God does enough times, one
will become as God is." -Dr. Hannibal Lector.
www.finalprotectivefire.com
http://picasaweb.google.com/Popeye8762
-hh
> "JRE" <noth...@nowhere.invalid> wrote:
> > capt.bill11 wrote:
> >> I know it's been discussed before. But I'm getting into a discussion
> >> on another forum with some one about the history of those limits. And
> >> whether or not they are arbitrary or not. And if they have any real
> >> basis as being safer than say any other number.
>
> >> So anybody care to refresh my memory on the history of those numbers?
>
> IIRC, there's a gear related military history significance about the 130 ft
> mark- something about older regs' breathing characteristics going to crap at
> that depths, and it just became an arbitrary rule-of-thumb.
Agreed. In part because early regs weren't balanced.
And what's also important to note is that the mathematics by which
130fsw also works out to be 1 ATM PPO2 was revisionist bullshit that
came much much later as an attempted "justification" of the 130fsw
value by the Recreational Agencies.
> ESG will be along to explain that coherently.
With pictures with diagrams and circles and dates.
> > My opinion:
>
> > 500 PSI is about 350 PSI usable before breathing gets harder, depending on
> > the regulator in use. 350 PSI is about 12% of a tank of air in an 3000
> > PSI tank, a bit over 8 cubic feet for an AL80. As margins go, 8 CF is a
> > bit thin at 130' (let's say a bit over a minute of moderate exercise), but
> > it beats "nothing" by a mile and it would probably be hard to talk
> > recreational divers using singles into greater margins.
>
> I think that's true.
>
> They gotta set a limit (for me to ignore) somewhere, and 750 or a grand
> would be too much.
In the early days, we also didn't have 3000psi tanks - a full steel
was ~2200 (if no plus rating). As such, a 1000psi rule would have
been half the tank.
Similarly, the lack of an SPG made the J valve ... and its spring
setting .. your reserve. Given that unbalanced regulators tend to
breathe like crap below ~250psi, a setting of 500psi for the J valve
would give you a warning starting at around 750, whereupon its release
would give you "enough" time to get up from ~100fsw.
Naturally, there's also stories of divers who accidentally tripped
their J and while still deep, sucked it dry, flipped, and then got a
surprise of no reserve.
-hh
John Van Ostrand
I've had divers trained over a decade ago or longer, tell me the limit
they were taught was 150'. Did it change to 130' over time or are they
remembering wrong?
Metric divers have a PSI limit of 40bar which is closer to 580PSI.
I've been in groups where they plan around 50bar.
John Van Ostrand
I think setting more conservative limits than needed have been
important to the dive industry, divers tend to be riskier people.
We were told things as if they were hard and fast truths only to find
out that they are loosely adhered to by typical divers and dive
operations. The 500PSI and 130' limits may be there just to keep
people above 150' and from surfacing with 0psi.
The conservative limits work well. I've seen divers panic (just a
little) when they exceed the limit by 1ft. And I can tell you how many
times a new buddy has signalled end-of-dive because of low air and
surfaced with well over 500PSI, because (s)he was worried about
passing the 500PSI limit. Maybe it's a good way to teach one to
monitor those things.
Joerg Hahn
John Van Ostrand wrote:
> I've had divers trained over a decade ago or longer, tell me the limit
> they were taught was 150'. Did it change to 130' over time or are they
> remembering wrong?
Is it a limit or more like "If you pass the course you are trained to to
dives within the limits of your course"-bullshit?
Here in Germany we have declining depth recommendations from way over
50m to 40m to 30m considered "deep" within 15years. Accidents do not
correlate. But buying plastic cards has increased.
> Metric divers have a PSI limit of 40bar which is closer to 580PSI.
Where? In EU it is for what you call "recreational" 50Bar.
But you may still plan 70 or 100Bar depending on what you dive.
> I've been in groups where they plan around 50bar.
Yes.
--
Die neuen Knips-Fotos aus dem Urlaub:
http://www.notabstieg.de/maledives-4-2009/index.html
http://www.grabmalkultur.de
Joerg Hahn
John Van Ostrand wrote:
> I think setting more conservative limits than needed have been
> important to the dive industry,
Sure, to sell deep dive courses.
> divers tend to be riskier people.
Riskier than who?
> operations. The 500PSI and 130' limits may be there just to keep
> people above 150' and from surfacing with 0psi.
The 50Bar is not. It is the assumption that 50Bar may be still there to
be used in case of unexpected difficulties, may be used as bailout for
your partner... etc.
> The conservative limits work well.
I would not call 50 Bar conservative, it is the minimum.
> passing the 500PSI limit. Maybe it's a good way to teach one to
> monitor those things
No. Asskicking might be a tool to help them learn "buddy awareness" and
to register air consumption and dive their plan.
Or being/living a good standard.
joerg
-hh
>
>
> I've had divers trained over a decade ago or longer, tell me the limit
> they were taught was 150'. Did it change to 130' over time or are they
> remembering wrong?
Might be geographical. The 130fsw limit was typical to the USA,
whereas BSAC & CMAS in Europe tended to use a different number. My
recollection was that it originally was 50m (165fsw); this might have
been changed over time to 45m (~150fsw).
In the meantime, I personally recall classroom work for dive tables
that involved air profiles to 180fsw. When asked "why so deep?", the
instructor's response was that this was a typical depth on a local
dive (NJ's "Texas Tower") and if we were going to be 'regular' divers,
it was likely that we would be doing that profile within a few
years. Needless to say, this was before the days of "fly someplace
warm" resort diving became widespread popular.
-hh
Joerg Hahn
> Might be geographical. The 130fsw limit was typical to the USA,
> whereas BSAC & CMAS in Europe tended to use a different number. My
> recollection was that it originally was 50m (165fsw); this might have
> been changed over time to 45m (~150fsw).
In France they still have a limit of 65m on air by law.
Which is 200fsw?
Joerg
Alan Browne
> Similarly, the lack of an SPG made the J valve ... and its spring
> setting .. your reserve. Given that unbalanced regulators tend to
> breathe like crap below ~250psi, a setting of 500psi for the J valve
> would give you a warning starting at around 750, whereupon its release
> would give you "enough" time to get up from ~100fsw.
>
> Naturally, there's also stories of divers who accidentally tripped
> their J and while still deep, sucked it dry, flipped, and then got a
> surprise of no reserve.
It seems (to me) that it would be simple enough to add a mechanical
device to the first reg. that "pings" (plonks, thuds, whatever) when a
certain pressure is reached without otherwise being part of the airflow
control.
--
gmail originated posts are filtered due to spam.
John Hanson
<alan....@FreelunchVideotron.ca> wrote in rec.scuba:
I would think that they could invent a pressure gauge that could
fairly accurately tell you the amount of air left in your tank. One
that is submersible and could be put on a high pressure hose and
clipped off to your left side D ring.
Greg Mossman
wrote:
Nowadays, ait-integrated dive computers will beep at you when you get
below a certain set point. Unfortunately this "feature" can be hard
or impossible to turn off, making them a nuisance when I deliberately
run my tank down well below 500 psi.
Alan Browne
Almost amusing.
However, the point being the saving of human lives despite the very high
inventory of same at present, redundant safety warnings are not
contraindicated. Especially if same are simply mechanical devices that
are fail passive and do not depend on electronics or visuals.
The J system seems to have been a first attempt at such warning, though
with drawbacks. The K or DIN system could easily have such a device
added into any of the medium pressure lines without it otherwise
interfering with operation.
Alan Browne
Can't you stop it?
On one of our dives somebody's computer would beep every time he went
through the 5 m safety stop depth. But that was the depth we were at
for that reef.
With bobbing up and down at about that depth it kept going off to
everyone's distraction.
John Hanson
<alan....@FreelunchVideotron.ca> wrote in rec.scuba:
If you're too incompetent to look at your SPG or to not know what your
SAC/DCR is, you're probably going to die from something else while
diving.
>
>The J system seems to have been a first attempt at such warning, though
>with drawbacks. The K or DIN system could easily have such a device
>added into any of the medium pressure lines without it otherwise
>interfering with operation.
Why complicate things with more stuff? Or add another failure point?
MatV
wrote:
This regulator was called Scubapro MK7, in the 70ies.
Today for rec and sports diving, pressure gauges are used. There was
also something called "reserve" a mechanism which choked supply when a
certain pressure was reached, and you had to pull a SS rod to open it
agein. Like in old Volkswagen Beetles.
Matthias
Curtis
> fairly accurately tell you the amount of air left in your tank. One
> that is submersible and could be put on a high pressure hose and
> clipped off to your left side D ring.
Damn, warn a buddy next time, mess on my keyboard.
Curtis
Alan Browne
I had added that in most environments where dependence on something is
important to safety, that redundant indicators and backup alarms are
often added.
Aviation comes to mind. There are fuel guages. And there are low fuel
warnings. There are all manner of engine state gauges. And there are
over limit warnings (sometimes to several layers, eg: blinking lights
AND alarms). There are altimeters and radar altimeters. The later has
both blinking lights and alarms to warn the pilot. And so on and so forth.
I would hardly call any air transport pilot incompetent unless he proved
himself to be so.
But I had deleted that all that. So, I'm adding it again.
It's so easy when diving to be enthralled at the diving and not check
the gauge. Certainly I didn't check it much on my first few dives until
it became a habit. But habits have a habit of being broken unless of
course they're bad habits.
>>
>> The J system seems to have been a first attempt at such warning, though
>> with drawbacks. The K or DIN system could easily have such a device
>> added into any of the medium pressure lines without it otherwise
>> interfering with operation.
>
> Why complicate things with more stuff? Or add another failure point?
So what if it fails if it's passive and fails passive?
Most of the time it will not fail. And possibly save a life - or least
reduce incidences of 0 press bottles being returned to the dive center.
Certainly such is less likely to fail than the computers people use to
watch their air (and then they have the backup of the gauges - oh! a
backup! Who'd have thought! On that note, one computer equipped diver
was PO'd to note that his computer didn't register the start time of the
dive ... )
Greg Mossman
wrote:
> On 10-02-09 16:34 , Greg Mossman wrote:
>
>
>
>
>
> > On Feb 9, 1:16 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca>
> > wrote:
> >> On 10-02-09 7:53 , -hh wrote:
>
> >>> Similarly, the lack of an SPG made the J valve ... and its spring
> >>> setting .. your reserve. Given that unbalanced regulators tend to
> >>> breathe like crap below ~250psi, a setting of 500psi for the J valve
> >>> would give you a warning starting at around 750, whereupon its release
> >>> would give you "enough" time to get up from ~100fsw.
>
> >>> Naturally, there's also stories of divers who accidentally tripped
> >>> their J and while still deep, sucked it dry, flipped, and then got a
> >>> surprise of no reserve.
>
> >> It seems (to me) that it would be simple enough to add a mechanical
> >> device to the first reg. that "pings" (plonks, thuds, whatever) when a
> >> certain pressure is reached without otherwise being part of the airflow
> >> control.
>
> > Nowadays, ait-integrated dive computers will beep at you when you get
> > below a certain set point. Unfortunately this "feature" can be hard
> > or impossible to turn off, making them a nuisance when I deliberately
> > run my tank down well below 500 psi.
>
> Can't you stop it?
Not on Uwatec models, so far as I know. I think the factory can do
it, but I never bothered. Instead, I gave it to Janna, since she's
really bad about running her air too low. I figure it won't stop her
from running her air low, but at least it will annoy the heck out of
her. Suunto first gives me a few beeps when I hit 725 psi (50 bar),
then the second alarm is customizable, so I set it to the lowest
setting of 10 bar and hope I don't hear that one go off.
> On one of our dives somebody's computer would beep every time he went
> through the 5 m safety stop depth. But that was the depth we were at
> for that reef.
The only alarm I've found useful is the depth alarm for reminding me
when I'm at my MOD (maximum operating depth) for nitrox. Normally,
that's not something I would exceed, but the problem with going that
deep on air or nitrox is that you're not always thinking clearly when
you get there. It likely saved my butt one time when I was swimming
frantically after a whaleshark in limited viz water where there were
no visible physical features that could allow me to sense my depth
beyond the pressure in my ears/sinuses. The computer beeped and I
glanced over to realize I was already at 127', not to mention out of
breath and low on air from chasing the bastard. Bye-bye whaleshark,
get that breathing under control, begin slow ascent while trying to
figure out which direction I came from. Live to dive another dive.
Thank you Suunto, it saved me from the siren call of the evil
whaleshark.
Alan Browne
You're too easily amused.
Alan Browne
> get that breathing under control, begin slow ascent while trying to
> figure out which direction I came from. Live to dive another dive.
> Thank you Suunto, it saved me from the siren call of the evil
> whaleshark.
A whaleshark is definitely on my list of "want to see".
Dan Bracuk
No such thing. The more easily amused one is, the more pleasant is
their life.
John Hanson
<alan....@FreelunchVideotron.ca> wrote in rec.scuba:
Well, in diving, you don't have an engine except your own body. I
suppose you could put a heart monitor on you as well as a respiration
monitor. Perhaps they could invent an underwater GPS too just like
pilots have. You wouldn't need cave line then in an overhead
environment. Oh wait...
You'll find that the more advanced and experienced you become, the
more you'll want to keep things simple.
>
>I would hardly call any air transport pilot incompetent unless he proved
>himself to be so.
>
>But I had deleted that all that. So, I'm adding it again.
>
>It's so easy when diving to be enthralled at the diving and not check
>the gauge. Certainly I didn't check it much on my first few dives until
>it became a habit. But habits have a habit of being broken unless of
>course they're bad habits.
If you're too incompetent to look at your SPG or to not know what your
SAC/DCR is, you're probably going to die from something else while
diving.
>
>>>
>>> The J system seems to have been a first attempt at such warning, though
>>> with drawbacks. The K or DIN system could easily have such a device
>>> added into any of the medium pressure lines without it otherwise
>>> interfering with operation.
>>
>> Why complicate things with more stuff? Or add another failure point?
>
>So what if it fails if it's passive and fails passive?
How would you make a passive system that tells you that you're low on
air? Please explain.
>
>Most of the time it will not fail. And possibly save a life - or least
>reduce incidences of 0 press bottles being returned to the dive center.
I own all my own tanks. All 10 of them.
>
>Certainly such is less likely to fail than the computers people use to
>watch their air (and then they have the backup of the gauges - oh! a
>backup! Who'd have thought! On that note, one computer equipped diver
>was PO'd to note that his computer didn't register the start time of the
>dive ... )
I would never have a computer that has a pressure sensor (I don't
trust them and my current VR3 doesn't have one nor could ever see one
made that would sense all 10 different gases that it currently can run
in your profile. I use 4 different gases on my deeper dives). I did
all my tech training with a computer that was worthless for the mixes
I use (it was used as a back up for my bottom timer). I dived with my
bottom timer, tables and my SPG and that got me through Advanced
Trimix using a travel gas and two deco gases as well as my back gas.
John Hanson
capt.bill11
During the course of our discussion I asked this question in regards
as to why having to have at least 500psi at the end of a dive was so
important:
"If you are hanging at 15 feet with less than 500 psi but with plenty
of air time for a safety stop what exactly is going to go wrong?"
I got this rather interesting reply:
- OK, have you ever seen someone get bent while hanging on the safety
stop bar? Actually, it happens a lot and I've seen it happen. With
enough air the diver can descend intil the pain stops and, if
necessary, wait for more air to be brought down so a prolonged deco
stop can be executed."
I found it a tad scary that he was advocating IWR as an excepted
practice for treating a potential bends hit in a recreational diver
scenario.
By the way, any body else see or hear of "a lot" of people getting
bent on the safety hang bar?
Capt. Bill
JRE
<snip>
> I've had divers trained over a decade ago or longer, tell me the limit
> they were taught was 150'. Did it change to 130' over time or are they
> remembering wrong?
This has definitely morphed over time.
In 1972, I was taught the limit was 300' on air (PPO2 around 2.1 ATM),
something I think is completely insane to plan for today.
If I recall correctly, Hal Watts used to teach people to dive up to 240'
on air (PP02 about 1.7) until he retired (not long ago), as one of his
students was one of my instructors. As something to experience in case
one must bail out to air when deep, I can understand this, but to plan
to dive that deep on air outside a carefully controlled training
environment is something I personally would not care to do.
From an O2 toxicity standpoint, anything past 220FSW (PPO2 1.6) seems
rather risky to me. For recreational divers I think 130' is reasonable
for most given the low frequency most divers dive and for the reasons I
outlined in a prior post.
(Then, there are divers whom I wouldn't consider safe in water deeper
than their knees, but that's a different story.)
--
John Eells
JRE
<snip>
> I would think that they could invent a pressure gauge that could
> fairly accurately tell you the amount of air left in your tank. One
> that is submersible and could be put on a high pressure hose and
> clipped off to your left side D ring.
SPGs were not commonplace when I learned to dive. We used the J valve
*and gas planning* to figure out what was what. Knowing one's air
consumption (SAC) rate was not optional if you went deep. This is a
tremendously good habit for any diver that nobody will teach you today
until you get to your first tech diving class.
Dive equipment is far better now. People were amazed when I did a dive
on a single but had forgotten to rig an inflator hose on the reg I
grabbed, and went anyway. I learned to dive by mouth inflating a horse
collar. I still know how (grin).
--
John Eells
JRE
<snip>
> However, the point being the saving of human lives despite the very high
> inventory of same at present, redundant safety warnings are not
> contraindicated. Especially if same are simply mechanical devices that
> are fail passive and do not depend on electronics or visuals.
>
> The J system seems to have been a first attempt at such warning, though
> with drawbacks. The K or DIN system could easily have such a device
> added into any of the medium pressure lines without it otherwise
> interfering with operation.
>
Complexity is often the enemy. I want a bare minimum of stuff between
me and my breathing gas, and a bare minimum of ways that gas can be put
at risk. I am likely to take a dim view of anything that increases the
complexity of my life support system unless there is a clearly
demonstrable and substantial countervailing safety advantage. If I plan
my dive and dive my plan and keep an eye on my pressure gauge, such
warning devices are superfluous and only add complexity and additional
risk of failure in my view.
Also, an intermediate pressure line warning would not be effective, as
it would warn you far too late. By the time tank pressure drops to IP,
you're about to suck hard for a few breaths before there is nothing left...
--
John Eells
1hogrider
>>
>> Can't you stop it?
>
> Not on Uwatec models, so far as I know. I think the factory can do
> it, but I never bothered. Instead, I gave it to Janna, since she's
> really bad about running her air too low. I figure it won't stop her
> from running her air low, but at least it will annoy the heck out of
> her. Suunto first gives me a few beeps when I hit 725 psi (50 bar),
> then the second alarm is customizable, so I set it to the lowest
> setting of 10 bar and hope I don't hear that one go off.
On the DataTalk software, there is a setting for "Buzzer On-Off" I have
never had need to mess around with it but I would guess that would turn
the alarm off and on.
Andy
JRE
<snip>
> I had added that in most environments where dependence on something is
> important to safety, that redundant indicators and backup alarms are
> often added.
>
> Aviation comes to mind. There are fuel guages. And there are low fuel
> warnings. There are all manner of engine state gauges. And there are
> over limit warnings (sometimes to several layers, eg: blinking lights
> AND alarms). There are altimeters and radar altimeters. The later has
> both blinking lights and alarms to warn the pilot. And so on and so forth.
>
> I would hardly call any air transport pilot incompetent unless he proved
> himself to be so.
What you're describing would be more appropriate for a submarine. Think
"hang glider" or "ultralight." Most general aviation airplanes have no
double-redundant instruments except VORTAC receivers and radios. There
are instrument combinations in a standard stack that allow partial panel
flight under IFR but that's about it.
Some general aviation pilots have trouble keeping the wings level
without a functional attitude indicator under VFR with good visibility.
Most learn they can use the horizon for reference without one. Think
of diving that way. You need to find the things that let you use
appropriate visual and knowledge-based references without over-reliance
on instrumentation. Even someone without an ATP endorsement can keep
the wings level without *anything* working on the panel, guess at
airspeeds from the pitch angle, and approximate TPA well from experience.
> But I had deleted that all that. So, I'm adding it again.
>
> It's so easy when diving to be enthralled at the diving and not check
> the gauge. Certainly I didn't check it much on my first few dives until
> it became a habit. But habits have a habit of being broken unless of
> course they're bad habits.
This is an exceptionally bad habit to have as a diver, just as failure
to plan and pay attention to fuel is an exceptionally bad habit for a
pilot. Nonetheless, the top reason for general aviation accidents
remains, for lo! these many years, running out of gas while aloft. Go
figure. The gauge is your friend. Read it often, no matter what.
>>>
>>> The J system seems to have been a first attempt at such warning, though
>>> with drawbacks. The K or DIN system could easily have such a device
>>> added into any of the medium pressure lines without it otherwise
>>> interfering with operation.
>>
>> Why complicate things with more stuff? Or add another failure point?
>
> So what if it fails if it's passive and fails passive?
>
> Most of the time it will not fail. And possibly save a life - or least
> reduce incidences of 0 press bottles being returned to the dive center.
I don't know how to make any device fail passively under all
circumstances. It will require seals to be able to be manufactured and
serviced. Seals fail. Having more of them is intrinsically bad.
> Certainly such is less likely to fail than the computers people use to
> watch their air (and then they have the backup of the gauges - oh! a
> backup! Who'd have thought! On that note, one computer equipped diver
> was PO'd to note that his computer didn't register the start time of the
> dive ... )
The number of computer failures (1) and the number of regulator failures
(2, 1 catastrophic) I have seen underwater so far argues against this logic.
--
John Eells
Geoff
KISS principle applies.
I dived with a HyperAqualand on my wrist. It beeped incessantly with
rate of ascent warning if I so much as moved my hand up in the water
column. Every diver I was with could hear it. Except me. I had to
strain to hear it. Hooking it to a D-ring made it less annoying for
others but I still couldn't hear it. One extra gizmo I didn't really
need.
I wear my hoseless computer for all dives but I still carry the SPG
and hose console in my kit in case of hardware failure. Nothing would
be worse than being on a trip and having a computer or transmitter
fail. At least with an SPG I can still dive on tables.
As for your cockpit redundancy analogy, all those gauges to scan and
read and commercial pilots still are bored to death in the cockpit.
Those gauges don't mean a thing when the wings are falling off or
you've busted your elevator jack screw trying to "troubleshoot" a
problem.
The key is awareness. You don't have to stare at the console for the
whole dive, it's OK to look at the scenery but a periodic glance at
your gauges will tell you instantly how your consumption is going to
affect your dive.
Douglas W. "Popeye" Frederick
"John Hanson" <jha...@northernlinks.com> wrote in message
news:2sk3n5hlst49rnnps...@4ax.com...
That was good.
--
--
Popeye
"If one does as God does enough times, one
will become as God is." -Dr. Hannibal Lector.
www.finalprotectivefire.com
http://picasaweb.google.com/Popeye8762
Douglas W. "Popeye" Frederick
"Alan Browne" <alan....@FreelunchVideotron.ca> wrote in message
news:4a6dnfxT1a1mQuzW...@giganews.com...
Can't let the gear do the diving for you.
Besides, diving as a whole is incredibly safe.
Douglas W. "Popeye" Frederick
"capt.bill11" <capt....@verizon.net> wrote in message
news:fbcb2a31-6e07-492b...@q4g2000yqm.googlegroups.com...
He's daft.
A "lot" of people don't get bent world wide, on a yearly basis.
> Capt. Bill
Douglas W. "Popeye" Frederick
"JRE" <not...@nowhere.invalid> wrote in message
news:hkstjv$7cm$1...@news.eternal-september.org...
> John Van Ostrand wrote:
> <snip>
>> I've had divers trained over a decade ago or longer, tell me the limit
>> they were taught was 150'. Did it change to 130' over time or are they
>> remembering wrong?
> <snip>
>
> This has definitely morphed over time.
>
> In 1972, I was taught the limit was 300' on air (PPO2 around 2.1 ATM),
> something I think is completely insane to plan for today.
>
> If I recall correctly, Hal Watts used to teach people to dive up to 240'
> on air (PP02 about 1.7) until he retired (not long ago), as one of his
> students was one of my instructors. As something to experience in case
> one must bail out to air when deep, I can understand this, but to plan to
> dive that deep on air outside a carefully controlled training environment
> is something I personally would not care to do.
>
> From an O2 toxicity standpoint, anything past 220FSW (PPO2 1.6) seems
> rather risky to me. For recreational divers I think 130' is reasonable
> for most given the low frequency most divers dive and for the reasons I
> outlined in a prior post.
I dive a 1.6 at all times, as I was taught.
Oxtoxes are grossly infrequent.
> (Then, there are divers whom I wouldn't consider safe in water deeper than
> their knees, but that's a different story.)
>
> --
> John Eells
Alan Browne
Not when the stimulus is low.
Dan Bracuk
>bent on the safety hang bar?
Not me.
Alan Browne
> Alan Browne wrote:
> <snip>
>> However, the point being the saving of human lives despite the very
>> high inventory of same at present, redundant safety warnings are not
>> contraindicated. Especially if same are simply mechanical devices that
>> are fail passive and do not depend on electronics or visuals.
>>
>> The J system seems to have been a first attempt at such warning,
>> though with drawbacks. The K or DIN system could easily have such a
>> device added into any of the medium pressure lines without it
>> otherwise interfering with operation.
>>
>
> Complexity is often the enemy. I want a bare minimum of stuff between me
> and my breathing gas, and a bare minimum of ways that gas can be put at
> risk. I am likely to take a dim view of anything that increases the
> complexity of my life support system unless there is a clearly
> demonstrable and substantial countervailing safety advantage. If I plan
> my dive and dive my plan and keep an eye on my pressure gauge, such
> warning devices are superfluous and only add complexity and additional
> risk of failure in my view.
I hate to sound argumentative, but such a device could easily be passive
in operation and fail passive as well. At worst (in fail) it would not
make the noise when the set pressure occurred. Tt would just be a few
ounces more mass on the system, out of the way, behind your head.
>
> Also, an intermediate pressure line warning would not be effective, as
> it would warn you far too late. By the time tank pressure drops to IP,
> you're about to suck hard for a few breaths before there is nothing left...
If the guage works down to near 0, then a device on that same line
(between the first reg and the gauge hose for example), can certainly be
made to "pop" at, for example, 600 or 800 psi. Long before the air runs
out. And for that matter remain passive and fail passive wrt to the
whole air system. Think of a transmitter for an integrated computer.
It cannot block airflow. It can fail and still not block airflow.
Alan Browne
> On Tue, 09 Feb 2010 16:16:36 -0500, Alan Browne
> <alan....@FreelunchVideotron.ca> wrote:
>
>> On 10-02-09 7:53 , -hh wrote:
>>
>>> Similarly, the lack of an SPG made the J valve ... and its spring
>>> setting .. your reserve. Given that unbalanced regulators tend to
>>> breathe like crap below ~250psi, a setting of 500psi for the J valve
>>> would give you a warning starting at around 750, whereupon its release
>>> would give you "enough" time to get up from ~100fsw.
>>>
>>> Naturally, there's also stories of divers who accidentally tripped
>>> their J and while still deep, sucked it dry, flipped, and then got a
>>> surprise of no reserve.
>>
>> It seems (to me) that it would be simple enough to add a mechanical
>> device to the first reg. that "pings" (plonks, thuds, whatever) when a
>> certain pressure is reached without otherwise being part of the airflow
>> control.
>
> KISS principle applies.
Exactly. Which is why I proposed a device that is small, passive, out
of the way and would fail passively as well.
Would still be a reminder to anyone to check their gauge when it popped
if they were in a bad habit mode.
Certainly people are adding transmitters for their computers. That is
is definitely not "simple".
Considering gear some people bring with them that could cause
distraction, photography being an easy example, such a device seems well
warranted.
Alan Browne
> Alan Browne wrote:
> <snip>
>> I had added that in most environments where dependence on something is
>> important to safety, that redundant indicators and backup alarms are
>> often added.
>>
>> Aviation comes to mind. There are fuel guages. And there are low fuel
>> warnings. There are all manner of engine state gauges. And there are
>> over limit warnings (sometimes to several layers, eg: blinking lights
>> AND alarms). There are altimeters and radar altimeters. The later has
>> both blinking lights and alarms to warn the pilot. And so on and so
>> forth.
>>
>> I would hardly call any air transport pilot incompetent unless he
>> proved himself to be so.
>
> What you're describing would be more appropriate for a submarine. Think
> "hang glider" or "ultralight." Most general aviation airplanes have no
> double-redundant instruments except VORTAC receivers and radios. There
> are instrument combinations in a standard stack that allow partial panel
> flight under IFR but that's about it.
See below regarding partial panel on VFR aircraft.
> Some general aviation pilots have trouble keeping the wings level
> without a functional attitude indicator under VFR with good visibility.
> Most learn they can use the horizon for reference without one. Think of
That's actually the sole way VFR flying is supposed to be taught.
However in the US there is a tendency to teach reliance on the AH for
VFR flight. In part this is due to the high haze levels in some areas
(NE US, California, etc.).
> diving that way. You need to find the things that let you use
> appropriate visual and knowledge-based references without over-reliance
> on instrumentation. Even someone without an ATP endorsement can keep the
> wings level without *anything* working on the panel, guess at airspeeds
> from the pitch angle, and approximate TPA well from experience.
On partial panel.
I used to teach instrument flying. Even on the most basic C-152 or 172
(factory equipped for VFR flight and optionally IFR) there is instrument
redundancy. A failed AH can is easily replaced with attention to the
T&B + airspeed. Failed HDG? You have the mag compass + T&B. etc.
These are all operated on segregated power sources and types (vacuum,
electric and pitot/static). Similar variants are on other co. aircraft.
However, without partial panel training, it is not so easy. This is the
first part of night VFR training, by the way.
(One of the Kennedy's refers - and he probably had a perfectly
functioning set of instruments.)
(And by the way, the reason you have two VOR receivers (no TACAN
receiver in most civil aircraft) is to make it more convenient to
identify intersection crossings in IFR. IFR flight does not require 2
VOR receivers. Nice to have to be sure, esp. with a DME of course.
You can legally file for IFR with surprising little equipment, actually,
but that just increases the workload leading to fatigue, confusion and
mistakes.
>> But I had deleted that all that. So, I'm adding it again.
>>
>> It's so easy when diving to be enthralled at the diving and not check
>> the gauge. Certainly I didn't check it much on my first few dives
>> until it became a habit. But habits have a habit of being broken
>> unless of course they're bad habits.
>
> This is an exceptionally bad habit to have as a diver, just as failure
> to plan and pay attention to fuel is an exceptionally bad habit for a
> pilot. Nonetheless, the top reason for general aviation accidents
> remains, for lo! these many years, running out of gas while aloft. Go
> figure. The gauge is your friend. Read it often, no matter what.
I get it. In fact I got it. But, given the environment and that the
primary source of life is air, it seems like a small enough addition to
warrant the extra warning when air is dropping.
The sole downside I would see to it is perhaps reliance on it as a "time
to surface" bell.
>>>>
>>>> The J system seems to have been a first attempt at such warning, though
>>>> with drawbacks. The K or DIN system could easily have such a device
>>>> added into any of the medium pressure lines without it otherwise
>>>> interfering with operation.
>>>
>>> Why complicate things with more stuff? Or add another failure point?
>>
>> So what if it fails if it's passive and fails passive?
>>
>> Most of the time it will not fail. And possibly save a life - or least
>> reduce incidences of 0 press bottles being returned to the dive center.
>
> I don't know how to make any device fail passively under all
> circumstances. It will require seals to be able to be manufactured and
> serviced. Seals fail. Having more of them is intrinsically bad.
The device would be removable in the same way as a transmitter. Why a
seal there would need more than an annual replacement is beyond me.
The part I would see failing is the popper. And in failing it would not
get into the air path. That would be the design goal. (eg: the orifice
from the pressure side to the device would be tiny since there is no
flow. So no failed parts from the device would be able to get out).
>
>> Certainly such is less likely to fail than the computers people use to
>> watch their air (and then they have the backup of the gauges - oh! a
>> backup! Who'd have thought! On that note, one computer equipped diver
>> was PO'd to note that his computer didn't register the start time of
>> the dive ... )
>
> The number of computer failures (1) and the number of regulator failures
> (2, 1 catastrophic) I have seen underwater so far argues against this
> logic.
Which means little to the guy who completely forgets 'cause he's low man
on the group and doesn't realize he's sucking air while trying to do
what the others are doing. And gee he brought a camera for the first
time and is getting too involved with that... a little ping noise should
bring him back to the one true question pretty quick.
I get the feeling the resistance here is based on established convention
rather than seeing the value in this. On the other hand gadgetry like
computers (including transmitters) are accepted and needed and cause
long discussions about what they're really saying.
Talk about complexity.
Enough said,
Newbie.
Geoff
You don't dive a profile waiting for a bell to ring like you're a
three minute egg. You don't suck your air down to 500 or even 750 psi
at 100 fsw before you decide, oops, it's time to head for the surface.
You plan your dive. You dive your plan. Departure from the plan may or
may not call for an abort of an open-water dive in a tourist group
situation but a low-air situation certainly shows a lack of awareness
of a number of factors and calls for re-training if it occurs more
often than rarely.
It's perfectly OK to be aware of your air consumption at depth and to
be calm about it. Awareness of it will calm you down because you will
know that you will not miss a decision point about when to turn around
or when to start your way up to your safety stop. A sharing air
situation is an abort condition for both buddies, not a method of
continuing the dive.
MatV
> On Tue, 09 Feb 2010 17:57:05 -0500, Alan Browne
> >>>> I would think that they could invent a pressure gauge that could
> >>>> fairly accurately tell you the amount of air left in your tank. One
> >>>> that is submersible and could be put on a high pressure hose and
> >>>> clipped off to your left side D ring.
Obviously they need to invent a brain that will not forget to look at
it ;-)
Or invent scuba education that.....
> Well, in diving, you don't have an engine except your own body. I
> suppose you could put a heart monitor on you as well as a respiration
> monitor.
See! That's what I like about my Draeger Dolphin. With it's back
mounted counterlungs, I can sense them expanding and collapsing, so I
can always monitor that I am breathing.
Ain't life simple!
> If you're too incompetent to look at your SPG or to not know what your
> SAC/DCR is, you're probably going to die from something else while
> diving.
With his amount of posting, I doubt that he will stay long enough in
the water ;-)
regards,
Matthias
JRE
> On 10-02-09 19:26 , JRE wrote:
>> Alan Browne wrote:
>> <snip>
>>> However, the point being the saving of human lives despite the very
>>> high inventory of same at present, redundant safety warnings are not
>>> contraindicated. Especially if same are simply mechanical devices that
>>> are fail passive and do not depend on electronics or visuals.
>>>
>>> The J system seems to have been a first attempt at such warning,
>>> though with drawbacks. The K or DIN system could easily have such a
>>> device added into any of the medium pressure lines without it
>>> otherwise interfering with operation.
>>>
>>
>> Complexity is often the enemy. I want a bare minimum of stuff between me
>> and my breathing gas, and a bare minimum of ways that gas can be put at
>> risk. I am likely to take a dim view of anything that increases the
>> complexity of my life support system unless there is a clearly
>> demonstrable and substantial countervailing safety advantage. If I plan
>> my dive and dive my plan and keep an eye on my pressure gauge, such
>> warning devices are superfluous and only add complexity and additional
>> risk of failure in my view.
>
> I hate to sound argumentative, but such a device could easily be passive
> in operation and fail passive as well. At worst (in fail) it would not
> make the noise when the set pressure occurred. Tt would just be a few
> ounces more mass on the system, out of the way, behind your head.
Nor am I. I'm just trying to make you understand. The choices are all
yours. It's not the idea of a warning device I object to. It's the
practical application of same.
>> Also, an intermediate pressure line warning would not be effective, as
>> it would warn you far too late. By the time tank pressure drops to IP,
>> you're about to suck hard for a few breaths before there is nothing
>> left...
>
> If the guage works down to near 0, then a device on that same line
> (between the first reg and the gauge hose for example), can certainly be
> made to "pop" at, for example, 600 or 800 psi. Long before the air runs
> out. And for that matter remain passive and fail passive wrt to the
> whole air system. Think of a transmitter for an integrated computer. It
> cannot block airflow. It can fail and still not block airflow.
>
It can also fail by being broken off at the first stage, causing a
fairly significant (but not instantly catastrophic) leak. It's
surprisingly easy to bump the overhead in a wreck, or under a ledge.
That vulnerability and the additional complexity of such a system vs. a
gauge on an HP hose are the reasons I did not buy an air integrated
computer.
--
John Eells
JRE
It's not *that* hazy here in the NE where I learned to fly even during
most of the summer.
>> diving that way. You need to find the things that let you use
>> appropriate visual and knowledge-based references without over-reliance
>> on instrumentation. Even someone without an ATP endorsement can keep the
>> wings level without *anything* working on the panel, guess at airspeeds
>> from the pitch angle, and approximate TPA well from experience.
>
> On partial panel.
>
> I used to teach instrument flying. Even on the most basic C-152 or 172
> (factory equipped for VFR flight and optionally IFR) there is instrument
> redundancy. A failed AH can is easily replaced with attention to the
> T&B + airspeed. Failed HDG? You have the mag compass + T&B. etc.
> These are all operated on segregated power sources and types (vacuum,
> electric and pitot/static). Similar variants are on other co. aircraft.
I'm not a CFII, but as it happens I knew that. Diving is similar in
this regard, actually. If your SPG is stuck or your transmitter broken
you still have a watch and knowledge of your SAC rate to tell you, with
a bit of calculation, how much gas you probably have left. You'll abort
anyway, of course, but it's not as scary as wondering when the gas will
run out.
I am certainly not trying to argue with you about flying, an area in
which as a CFII you are far more qualified than I, with my mere (and
very dusty) SEL license.
> However, without partial panel training, it is not so easy. This is the
> first part of night VFR training, by the way.
>
> (One of the Kennedy's refers - and he probably had a perfectly
> functioning set of instruments.)
Yup.
> (And by the way, the reason you have two VOR receivers (no TACAN
> receiver in most civil aircraft) is to make it more convenient to
> identify intersection crossings in IFR. IFR flight does not require 2
> VOR receivers. Nice to have to be sure, esp. with a DME of course.
DMEs are indeed very nice. GPSs are nicer, though (grin).
I had a full radio stack failure on my first solo cross-country. But I
still had a sectional, a compass, eyes, and an instructor who drilled
into me that "things break." It was trivially easy to navigate without
the electronics.
> You can legally file for IFR with surprising little equipment, actually,
> but that just increases the workload leading to fatigue, confusion and
> mistakes.
>
>>> But I had deleted that all that. So, I'm adding it again.
>>>
>>> It's so easy when diving to be enthralled at the diving and not check
>>> the gauge. Certainly I didn't check it much on my first few dives
>>> until it became a habit. But habits have a habit of being broken
>>> unless of course they're bad habits.
>>
>> This is an exceptionally bad habit to have as a diver, just as failure
>> to plan and pay attention to fuel is an exceptionally bad habit for a
>> pilot. Nonetheless, the top reason for general aviation accidents
>> remains, for lo! these many years, running out of gas while aloft. Go
>> figure. The gauge is your friend. Read it often, no matter what.
>
> I get it. In fact I got it. But, given the environment and that the
> primary source of life is air, it seems like a small enough addition to
> warrant the extra warning when air is dropping.
>
> The sole downside I would see to it is perhaps reliance on it as a "time
> to surface" bell.
The other downside is that as your SAC rate decreases and you go deeper,
gas won't be the limiting factor in many of your dives. The no-deco
limit (NDL) will. Also, if you have a buddy that whose SAC rate is
greater than your own, your low-on-gas warning device will not tell him
or you about his gas status. My computers (both of them) beep when I
approach or exceed the NDL and when I exceed 130'. Most of the time I
don't hear them over normal breathing noise, but I always know within a
minute or two when my turn time is coming up and what my pressure is
within 100 PSI or so. These are part of my scan just as glances at the
altimeter and airspeed are part of a pilot's.
>>>>>
>>>>> The J system seems to have been a first attempt at such warning,
>>>>> though
>>>>> with drawbacks. The K or DIN system could easily have such a device
>>>>> added into any of the medium pressure lines without it otherwise
>>>>> interfering with operation.
>>>>
>>>> Why complicate things with more stuff? Or add another failure point?
>>>
>>> So what if it fails if it's passive and fails passive?
>>>
>>> Most of the time it will not fail. And possibly save a life - or least
>>> reduce incidences of 0 press bottles being returned to the dive center.
>>
>> I don't know how to make any device fail passively under all
>> circumstances. It will require seals to be able to be manufactured and
>> serviced. Seals fail. Having more of them is intrinsically bad.
>
> The device would be removable in the same way as a transmitter. Why a
> seal there would need more than an annual replacement is beyond me.
>
> The part I would see failing is the popper. And in failing it would not
> get into the air path. That would be the design goal. (eg: the orifice
> from the pressure side to the device would be tiny since there is no
> flow. So no failed parts from the device would be able to get out).
If it's removable, the seal between the device and the reg can fail, and
sometimes will, no matter what's inside it. The device, whatever it is,
will either be more massive than the plug it replaces, adding stress to
the seal or worse, will be in between the first stage and the existing
HP hose or transmitter, adding another seal to the system. If we want
to have this sort of device then it should be internal to the first
stage without adding any points of reg failure including external HP
seals. I would not let such an internal fail-safe device deter me from
buying a reg but I still wouldn't bolt anything extra on.
>>> Certainly such is less likely to fail than the computers people use to
>>> watch their air (and then they have the backup of the gauges - oh! a
>>> backup! Who'd have thought! On that note, one computer equipped diver
>>> was PO'd to note that his computer didn't register the start time of
>>> the dive ... )
>>
>> The number of computer failures (1) and the number of regulator failures
>> (2, 1 catastrophic) I have seen underwater so far argues against this
>> logic.
>
> Which means little to the guy who completely forgets 'cause he's low man
> on the group and doesn't realize he's sucking air while trying to do
> what the others are doing. And gee he brought a camera for the first
> time and is getting too involved with that... a little ping noise should
> bring him back to the one true question pretty quick.
If he hears it, it will perhaps make up for this aspect of his lack of
situational awareness. But like those Colgan Air pilots, if you accept
the NTSB's conclusions, perhaps that won't be enough (they pulled up
when the yoke shaker came on).
A warning device is only as good as the diver's reaction to it, and I'll
argue that not having sufficient situational awareness in the water to
develop a habitual scan that includes one's air status is inherently
dangerous in more ways than just this one. You need to be "ahead of the
dive" just as you need to be "ahead of the airplane."
> I get the feeling the resistance here is based on established convention
> rather than seeing the value in this. On the other hand gadgetry like
> computers (including transmitters) are accepted and needed and cause
> long discussions about what they're really saying.
I *do* see the value in warning devices. Honest! I also see the risks
of adding them to certain systems and of over-reliance on them. It's
the balance between them that matters. If we evaluate and balance the
risks and can show that we are statistically better off with the device
you propose then I'm all for it. Put one inside my next new reg!
But for the example you chose, not everyone accepts transmitters because
the risk/benefit equation for them does not work them in all
environments. They fail more, and in more ways (e.g., loss of
communication, leak due to damage incurred when the thing takes a solid
bump from something overhead), than a simple SPG. And many of us dive
with either a second computer or knowledge of depth and time and limits
to back up the first computer. (I know one exceptionally unlucky diver
who seems to have one computer fail a year whether he needs it to or
not. It's often the communication between his transmitter and computer
that fails.)
Having said all that, for open water diving the benefits of transmitters
(consolidated information, shorter scan, etc.) can outweigh the slight
risks. But I rarely see wreck or cave divers using one, even in open water.
> Talk about complexity.
I am not anti-complexity. As other posters to this forum do, I jump in
the water with a fairly complex system that has many more points of
failure than you have diving with a single, but which also offers
redundancy for most of them. It's unnecessary complexity in my primary
life support system I am wary of, even though I dive with at least two
of them (not counting travel and deco regs) virtually all the time.
> Enough said,
Well, maybe (grin).
> Newbie.
>
--
John Eells
Greg Mossman
> It can also fail by being broken off at the first stage, causing a
> fairly significant (but not instantly catastrophic) leak. It's
> surprisingly easy to bump the overhead in a wreck, or under a ledge.
> That vulnerability and the additional complexity of such a system vs. a
> gauge on an HP hose are the reasons I did not buy an air integrated
> computer.
But HP hoses can likewise be bumped. Even worse, they can be cut or
they can rupture. And they are an extra entanglement hazard, even
when routed and clipped off. And that gauge part is much more liable
to get damaged, even properly clipped off, then the little watch
around my wrist (unless I'm banging around in a hole trying to catch a
lobster). And that extra hose and its attached gauge aren't as
streamlined, whatever that's worth.
All of those disadvantages and failures points are the reasons I did
not buy a HP hose and gauges.
Greg Mossman
> It's perfectly OK to be aware of your air consumption at depth and to
> be calm about it. Awareness of it will calm you down because you will
> know that you will not miss a decision point about when to turn around
> or when to start your way up to your safety stop. A sharing air
> situation is an abort condition for both buddies, not a method of
> continuing the dive.
Why, necessarily? If one diver continually runs short on air and his
buddy continually returns with more air than the recommended minimum,
assuming only one size tank is available such as at the standard
resort setting, what's the harm in balancing out the air a bit if it
can prolong the dive by another few minutes?
John Van Ostrand
> Is it a limit or more like "If you pass the course you are trained to to
> dives within the limits of your course"-bullshit?
It seems normal to me that new OW divers should limit their depth to
60ft. The courses reinforce that through "rules". It also means that
divers will feel compelled to take AOW courses before going deeper. I
don't have a problem with that, other than it should be one course
with breaks to obtain dive experience.
John Van Ostrand
> John Van Ostrand wrote:
> > I think setting more conservative limits than needed have been
> > important to the dive industry,
>
> Sure, to sell deep dive courses.
No to reinforce the idea that diving is dangerous and prevent divers
for going too far. Are you suggesting that "no limits" should be
taught?
> > divers tend to be riskier people.
>
> Riskier than who?
Diving adds risk to your life, divers tend to be more risky.
> > operations. The 500PSI and 130' limits may be there just to keep
> > people above 150' and from surfacing with 0psi.
>
> The 50Bar is not. It is the assumption that 50Bar may be still there to
> be used in case of unexpected difficulties, may be used as bailout for
> your partner... etc.
We learned the "rule of thirds" to conserve enough gas for our buddy.
The 500PSI limit was taught for unforeseen contingencies, like having
to dive immediately to avoid something. I can see your point that to
rise from depth might take that much additional air to support a
panicky buddy though.
> > The conservative limits work well.
>
> I would not call 50 Bar conservative, it is the minimum.
>
> > passing the 500PSI limit. Maybe it's a good way to teach one to
> > monitor those things
>
> No. Asskicking might be a tool to help them learn "buddy awareness" and
> to register air consumption and dive their plan.
Dive planning is taught as a necessity but I rarely see it done
properly practice. At resort dives it's the briefing, on unorganized
dives it's usually over simplified.
You can rest on your opinion that "asskicking" should be all that's
needed but that won't work on everyone.
> Or being/living a good standard.
That I agree on.
John Van Ostrand
limited skill is involved?
We have it easier than the last generation of divers. We have SPGs and
computers and such. Most divers have no idea of their SAC rate, most
just follow the DM.
What's the next innovation that will remove yet another critical skill
from diving?
Geoff
Normally, not much harm, but how is that a "good" dive or good habit
to get into? Is a few more minutes of bottom time worth the safety of
two people? If you and your buddy are diving on air-integrated
computers, what does that tell your computer when you are continuing
to dive on zero air? Why are you screwing up your buddies profile? You
are trained to sign the OOA, grab his octo, signal OK, signal
agreement to ascend and begin proper, coordinated ascent. Why would
anyone encourage others to ignore basic training?
Granted, in today's resort or big-boat dive community the buddy system
is not tightly coupled but the point, I think, is safety margin. A
safe diver pays attention to their physical fitness, their air
consumption, their diving skills and their buddy. They dive their own
profile and skill level. They work on relaxing and gaining confidence
and improving their skills. This makes for better, safer, longer
dives. This trains you to improve your skills at your own rate on your
own behalf.
In a gang-dive or drift dive it's probably better to be aware of your
consumption, signal low-air and that you are beginning a slow solo
ascent and let your buddy continue the dive with the group. During my
air-sucker period that's exactly what I ended up doing. It wasn't
until I was pushing 30 or 40 dives that my bottom time significantly
improved. Yep, I surfaced exactly one time so far, with 300 PSI on my
gauge and I didn't like it either but I leaned to become a better
diver and to know my equipment and my capabilities.
Alan Browne
> Awareness. Awareness. Awareness.
>
> You don't dive a profile waiting for a bell to ring like you're a
> three minute egg.
I never said different, in fact I mentioned the scenario above as a
negative in the idea - complacent dependency.
But I stand on the notion that given how important air alone is to the
whole enterprise that a backup warning is merited for those who may from
time to time get otherwise distracted.
Curtis
>>
>> No such thing. The more easily amused one is, the more pleasant is
>> their life.
>
> Not when the stimulus is low.
Maybe tis you who is too uptight? Troll maybe?
Sit Down, Hold On, Shut UP, Listen to your Elders & Enjoy the Ride.
Curtis
Ecnerwal
Geoff <ge...@invalid.invalid> wrote:
> On Wed, 10 Feb 2010 06:56:12 -0800 (PST), Greg Mossman
> <mos...@qnet.com> wrote:
>
> >On Feb 10, 1:09�am, Geoff <ge...@invalid.invalid> wrote:
> >
> >> It's perfectly OK to be aware of your air consumption at depth and to
> >> be calm about it. Awareness of it will calm you down because you will
> >> know that you will not miss a decision point about when to turn around
> >> or when to start your way up to your safety stop. A sharing air
> >> situation is an abort condition for both buddies, not a method of
> >> continuing the dive.
> >
> >Why, necessarily? If one diver continually runs short on air and his
> >buddy continually returns with more air than the recommended minimum,
> >assuming only one size tank is available such as at the standard
> >resort setting, what's the harm in balancing out the air a bit if it
> >can prolong the dive by another few minutes?
>
> Normally, not much harm, but how is that a "good" dive or good habit
> to get into? Is a few more minutes of bottom time worth the safety of
> two people?
Consider, if you will, and granting it's rather rare the case where
airhog sucks down tank, borrows form buddy, and while borrowing from
buddy, buddy's regulator fails. Where's the backup now? That's one good
"why not?"
--
Cats, coffee, chocolate...vices to live by
JRE
Nonetheless, I have yet to see an HP hose or gauge failure that required
a dive to be aborted. HP hoses are pretty tough. My SPG's case is 2"
of solid metal about 1/2" thick with a slightly recessed glass face.
It's not in a bulky console, and it's pretty hard to hurt it badly
enough to make it leak air. Also, the moment arm on the fitting at the
end of an HP hose is a lot shorter than the one presented by a typical
transmitter, and the hose material itself softens the blow, reducing
stress on the fittings.
I have seen transmitter link failures, though I have not personally seen
one broken, or broken off. Since I have no electronic remote
connection, though, it can't fail. Since the gauge is mechanical, the
batteries cannot go dead. It just works.
I've also seen a couple of LP hose failures as well as both HP (not HP
hose or SPG) and IP O-ring failures. One of the HP O-ring failures, the
seal between the DIN fitting and the first stage, made a pretty
spectacular frothing area at least 30' across on the surface, and in the
resulting emergency one diver missed 12 minutes of deco (and was OK) and
the diver's buddy finished deco without a mask by counting the seconds
and guessing at depth changes using his hand widths on the up line.
Seeing these things has made me very wary of delicate things and
additional points of failure.
All anecdotal, I'll grant you. Anyone have a better sense of the
relative failure rates for these components? Maybe what I've seen
hasn't been typical.
Last, I'll submit that the SPG on an HP hose is no more an entanglement
hazard than an octo. In fact, since the SPG is a lot smaller than a
second stage, I'd argue it's a smaller hazard, particularly when clipped
off.
As I said before, for open water diving within recreational limits, the
operational simplicity of an air integrated computer might well outweigh
the disadvantages I perceive for their use in real or virtual overhead
environments. If you disagree, that's OK. We're each free to choose
between the alternatives.
--
John Eells
Greg Mossman
> As I said before, for open water diving within recreational limits, the
> operational simplicity of an air integrated computer might well outweigh
> the disadvantages I perceive for their use in real or virtual overhead
> environments. If you disagree, that's OK. We're each free to choose
> between the alternatives.
No, I'd tend to agree with your assessment as far as real overhead
environments go. And I wouldn't deliberately attempt a virtual
overhead, i.e. deco, without at least a backup timer/depth gauge. I
can live without the pressure gauge since I know my air consumption
intimately and still check my tank pressure rather anally, so I'd know
within a minute or two exactly how much air I had left before the
computer died. And if I were doing a deliberate deco dive, I'd have
been smart enough to plan my dive and write my planned stops on a
slate and also figure out my air consumption, just like I was taught.
And I'd probably have a buddy with me too! Backup on the depth and
time is more crucial than backup on the tank pressure for well-planned
dives.
Greg Mossman
Getting a little defensive because I'm not the only one who thinks
your attempts at humor pitiful? He's been a very good student and
like any very good student he's been asking good intelligent
questions. Thanks to him, this is the only decent dive-related thread
in a long time here. Your shit attitude will only ensure rec.scuba
sinks into a mud hole, and unlike you, not all of us prefer mud holes.
Greg Mossman
> Normally, not much harm, but how is that a "good" dive or good habit
> to get into? Is a few more minutes of bottom time worth the safety of
> two people? If you and your buddy are diving on air-integrated
> computers, what does that tell your computer when you are continuing
> to dive on zero air? Why are you screwing up your buddies profile? You
> are trained to sign the OOA, grab his octo, signal OK, signal
> agreement to ascend and begin proper, coordinated ascent. Why would
> anyone encourage others to ignore basic training?
Because basic training is, by name, basic. I do a lot of things now
that I was told not to do in basic training, such as hold my breath on
occasion when I'm taking a picture, or go deeper than 100'. I know
the risks and I have enough knowledge and experience to properly
evaluate them. I wasn't "encouraging" anyone, just questioning your
hardfast "rule".
As for the air-integrated computer, it's still tracking my depth and
time for NDL purposes. If it suddenly senses I'm really really good
on air, that's only gonna affect the "remaining air time" calculation
and only an idjit would base their dive on that number alone.
> In a gang-dive or drift dive it's probably better to be aware of your
> consumption, signal low-air and that you are beginning a slow solo
> ascent and let your buddy continue the dive with the group. During my
> air-sucker period that's exactly what I ended up doing. It wasn't
> until I was pushing 30 or 40 dives that my bottom time significantly
> improved. Yep, I surfaced exactly one time so far, with 300 PSI on my
> gauge and I didn't like it either but I leaned to become a better
> diver and to know my equipment and my capabilities.
And when you and your buddy have been pushing 300 or 400 dives
together, you get to know not only your equipment and your
capabilities well, but your buddy's too. Your air is your buddy's
air, that's a common mantra in tech diving. What's wrong with putting
that into practice?
Greg Mossman
<MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote:
> Consider, if you will, and granting it's rather rare the case where
> airhog sucks down tank, borrows form buddy, and while borrowing from
> buddy, buddy's regulator fails. Where's the backup now? That's one good
> "why not?"
Yep, and consider, if you will, and granting it's rather rare, the
case where a meteor strikes and kills all of us. What would be the
point of not sharing her air then? No backup?
-hh
> Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote:
>
> > It seems (to me) that it would be simple enough to add a mechanical
> > device to the first reg. that "pings" (plonks, thuds, whatever) when a
> > certain pressure is reached without otherwise being part of the airflow
> > control.
>
I've been reading all the responses looking for someone to have
already said this.
The Scubapro Mk7 had the nickname of the "Honker" due to this
feature.
> Today for rec and sports diving, pressure gauges are used. There was
> also something called "reserve" a mechanism which choked supply when a
> certain pressure was reached, and you had to pull a SS rod to open it
> agein. Like in old Volkswagen Beetles.
Ah, the reserve gasoline tank in the old Beetles. I recall that Dad's
'63 bug had one, but I never knew too much about it. Wasn't this
designed like a "pocket" higher up in the tank that wouldn't get
refilled unless you got a full tank of gas?
-hh
Joerg Hahn
Douglas W. "Popeye" Frederick wrote:
> I dive a 1.6 at all times, as I was taught.
>
> Oxtoxes are grossly infrequent.
I don`t understand this. Do You mean
a) within 1.6, Oxtox(Paul Bert)effects are grossly infrequent,
but you had?
b) within 1.6, Oxtox(Paul Bert)effects are grossly infrequent,
and you never had?
I would be interested in finding any source of oxtox within 1.6.
Even considering 1.6 to 2.0 range with an resonable short 5 to 10
minutes exposure I doubt finding one.
lg
Joerg
--
Die neuen Knips-Fotos aus dem Urlaub:
http://www.notabstieg.de/maledives-4-2009/index.html
http://www.grabmalkultur.de
Joerg Hahn
Greg Mossman wrote:
>> Can't you stop it?
>
> Not on Uwatec models, so far as I know.
It depends on model.
1. you can set end of dive pressure which is used for calculating RBT
2. You can set "gain" for breathing alarm
3. You can switch off beeps for alarms
but you cannot switch off beeps for emergency like fast ascend and
ceilings.
Also, diving several EANs, you cannot stop beeping for gas switching.
I think the factory can do
> it, but I never bothered.
Datatalk is the software for older Uwatecs.
> Instead, I gave it to Janna, since she's
So at least, she got a good computer ;-)
What Model is it?
Joerg Hahn
Greg Mossman wrote:
> Your air is your buddy's
> air, that's a common mantra in tech diving. What's wrong with putting
> that into practice?
You, always benefitting. Your SAC sucks, Hanna`s doesn`t ;-)
Joerg Hahn
John Van Ostrand wrote:
> On Feb 9, 2:31 pm, Joerg Hahn <d...@notabstieg.de> wrote:
>> John Van Ostrand wrote:
>>> I think setting more conservative limits than needed have been
>>> important to the dive industry,
>> Sure, to sell deep dive courses.
>
> No to reinforce the idea that diving is dangerous and prevent divers
> for going too far. Are you suggesting that "no limits" should be
That is not what I said.
In ancient times the diving course was sufficent to let educated divers
dive within a much deeper ranger.
To reach more people, education was simplified, the course much easier
to pass. The educated diver could not reach eq 65m anymore.
Therefore the agencies had to sell more advanced courses with same
knowledge, which was included in the former, older courses.
All I am suggesting is that divers should be trained for being
autonomous, adult, responsible. Limits then are Kindergarten.
Rest is self regulating Darwin. And would be still less dangerous than
driving.
>> Riskier than who?
>
> Diving adds risk to your life, divers tend to be more risky.
huuh? Getting out of bed adds risk to your life.
Diving is way less risky compared to skiing, driving (not to mention
motorbiking) and even skateboarding. All this are accepted sports or tasks.
> We learned the "rule of thirds" to conserve enough gas for our buddy.
In my case, that is the mentioned 70bars. Given usually 200bars full
tank. 50bar is 1 fourth of 200. Used for plain, warm dives.
> The 500PSI limit was taught for unforeseen contingencies, like having
> to dive immediately to avoid something.
Is that about 1 fourth or 1 third of full tank?
> I can see your point that to
> rise from depth might take that much additional air to support a
> panicky buddy though.
First, exactly _this_ was not my point. The 50bar-1/4 is rest, buffer,
reserve. It is not used. Only for unforseen purpose/emergency/not
whalesharks.
Second, "rise from depth" is way before reaching 50Bar. Depending on
dive I plan and dive to be free of deko and in sight of ladder of boat
at 50bar. On deeper dives due to safety/redundancy considerations this
marker is set more to 70bar reserve.
I do not dive with panicking divers. If I dive with people who might
have a slight chance to panic, I do not do any deep/blue. I do not do
any tasks. I do have air for both of us and make shure that the diver is
not panicking at all, period.
> Dive planning is taught as a necessity but I rarely see it done
> properly practice. At resort dives it's the briefing, on unorganized
> dives it's usually over simplified.
I do not do "resort dives". It is more like "if we reach location, let
my buddy and me go first and do not wait for us for supper".
> You can rest on your opinion that "asskicking" should be all that's
> needed but that won't work on everyone.
If they want to dive with me, I prefer asskicking. Otherwise they do not
dive with me. I am setting the minimum standard. What others do, is not
of my interest. They don`t have to care about me. I am fine, as long as
they do not imply any rules of theirs on me.
joerg
Greg Mossman
> Hi Greg,
>
> Greg Mossman wrote:
> >> Can't you stop it?
>
> > Not on Uwatec models, so far as I know.
>
> It depends on model.
> 1. you can set end of dive pressure which is used for calculating RBT
> 2. You can set "gain" for breathing alarm
> 3. You can switch off beeps for alarms
> but you cannot switch off beeps for emergency like fast ascend and
> ceilings.
>
> Also, diving several EANs, you cannot stop beeping for gas switching.
>
> I think the factory can do
>
> > it, but I never bothered.
>
> Datatalk is the software for older Uwatecs.
>
> > Instead, I gave it to Janna, since she's
>
> So at least, she got a good computer ;-)
> What Model is it?
Aladin Air Z O2, originally purchased to go with the Draeger that's
sitting in my garage. It's a nice computer, but basic. No
temperature. No time of day. And I'm not too keen on the wrist band.
Joerg Hahn
> Aladin Air Z O2, originally purchased to go with the Draeger that's
> sitting in my garage. It's a nice computer, but basic. No
> temperature. No time of day. And I'm not too keen on the wrist band.
Yeah, kinda old. No compare to D9.
Same old days, where Suunto had its "companion".
Joerg Hahn
Greg Mossman wrote:
> Aladin Air Z O2, originally purchased to go with the Draeger that's
> sitting in my garage. It's a nice computer, but basic. No
> temperature. No time of day. And I'm not too keen on the wrist band.
oh, it has temperatur and time and date. But it does not display it.
Only visible thru readout via PC.
MatV
wrote:
In the nineties, a German company devellopped an autopilot device
replacing your BCD`s inflator assembly providing automatic presettable
depth and bouancy control, as well an ntegrated decompression
including ascent feature following Buelmann's model.
Matthias
Greg Mossman
> Greg Mossman wrote:
> > Aladin Air Z O2, originally purchased to go with the Draeger that's
> > sitting in my garage. It's a nice computer, but basic. No
> > temperature. No time of day. And I'm not too keen on the wrist band.
>
> oh, it has temperatur and time and date. But it does not display it.
> Only visible thru readout via PC.
It kind of sucks that you have to bring a waterproof PC down with you
just to know what time it is. When I do my solo afternoon dive in
Bonaire, for instance, it's absolutely imperative I don't lose track
of time or I might miss happy hour.
Water temp is good to know too. When we dove Cannibal Rock for the
first time, I was all ready for the often chilly water in my 5mm FJ
suit - they said it often gets into the mid-60s. Naturally I screamed
like a girlie when I jumped into that frigid water, but then I looked
at my trusty Suunto which said it was a relatively toasty 79 degrees.
That fact established, I was very warm for the rest of the dive. Had
I been diving my Uwatec, I would have been cold and miserable.
MatV
wrote:
> On 10-02-10 4:09 , Geoff wrote:
>
> > Awareness. Awareness. Awareness.
>
> > You don't dive a profile waiting for a bell to ring like you're a
> > three minute egg.
>
> I never said different, in fact I mentioned the scenario above as a
> negative in the idea - complacent dependency.
>
> But I stand on the notion that given how important air alone is to the
> whole enterprise that a backup warning is merited for those who may from
> time to time get otherwise distracted.
>
In commercial scuba appliances a double independant pressure control
is obligatory. One is to function in no vis environments.
Matthias
MatV
> Hi Douglas,
>
> Douglas W. "Popeye" Frederick wrote:
>
> > I dive a 1.6 at all times, as I was taught.
> >
> > Oxtoxes are grossly infrequent.
>
> I don`t understand this. Do You mean
>
> a) within 1.6, Oxtox(Paul Bert)effects are grossly infrequent,
> but you had?
>
> b) within 1.6, Oxtox(Paul Bert)effects are grossly infrequent,
> and you never had?
>
> I would be interested in finding any source of oxtox within 1.6.
> Even considering 1.6 to 2.0 range with an resonable short 5 to 10
> minutes exposure I doubt finding one.
Hi Joerg,
Ingo F. of the Lusitania team had an oxtox on 1,6. FFM saved him.
Otherwise, people who suffered an oxtox are now grossly infrequent,
that's right.
LG,
Matthias
Greg Mossman
wrote:
Self-clearing masks would be cool, for those divers who still haven't
mastered the purge valve. And why can't they make boat ladders like
escalators, so you just have to step on and let the ladder bring you
up?
Alan Browne
> And when you and your buddy have been pushing 300 or 400 dives
> together, you get to know not only your equipment and your
> capabilities well, but your buddy's too. Your air is your buddy's
> air, that's a common mantra in tech diving. What's wrong with putting
> that into practice?
In that case my buddy will always be my SO! When I'm at 600 she's at
1400. A friend indeed! If I ever manage to tame my air consumption, we
should be able to add a good 10 minutes to dives to 60 or so feet.
Alan Browne
I'm talking about a passive warning device, not a control.
Alan Browne
> On Feb 10, 8:08 am, John Van Ostrand<john.van.ostr...@gmail.com>
> wrote:
>> Does anyone foresee dive technology getting to a point where much more
>> limited skill is involved?
>>
>> We have it easier than the last generation of divers. We have SPGs and
>> computers and such. Most divers have no idea of their SAC rate, most
>> just follow the DM.
>>
>> What's the next innovation that will remove yet another critical skill
>> from diving?
Skill sets evolve according to technology, esp. technologies that
improve safety and/or reduce workload. (Having said that I haven't used
a computer for diving yet - and for the diving I do the tables seem more
than adequate).
When I did my first pre-PADI dive in 2003 I was surprised that everyone
has two regulators on their systems making the old buddy breathe
essentially redundant (we still trained for the buddy breathe).
In fact, I remember reading about the "first" dive computer a couple
decades or so ago. A black box with a hole in it and a light or two
(what I seem to remember). Now computers seem near ubiquitous.
Technologies don't replace technique when they show up, but when that
technology proves to be reliable, useful, workload decreasing and esp.
safety enhancing.
It is thus in everything. Many people can't drive manual shift cars (at
least in N. America). Not that it's hard to learn.
Many people can't perform a high performance stop in their cars, most
especially in a turn. (Now just max out the brakes and wait while
comfortably steering). Some can't get off a slippery patch on the ice
without spinning: now, anti slip manages the torque. (there are even
cars that parallel park for you...)
Such lists may be endless.
John Van Ostrand
> In ancient times the diving course was sufficent to let educated divers
> dive within a much deeper ranger.
> To reach more people, education was simplified, the course much easier
> to pass. The educated diver could not reach eq 65m anymore.
> Therefore the agencies had to sell more advanced courses with same
> knowledge, which was included in the former, older courses.
I can see the business sense that this makes. More divers=more
income.
I'm told that BSAC, for example, include OW, AOW and rescue in the
basic training. Were the skill requirements for original courses that
deep?
> All I am suggesting is that divers should be trained for being
> autonomous, adult, responsible. Limits then are Kindergarten.
> Rest is self regulating Darwin. And would be still less dangerous than
> driving.
Relying on natural selection would result in government regulation of
the industry. Higher fatalities would make diving appear more risky so
fewer divers would dive. Fewer divers means fewer dive operations,
shops, manufacturers resulting in fewer and more expensive options.
It's not that economy is the goal, but, regardless of how or why
people dive safely the more that dive the more choices divers have.
> huuh? Getting out of bed adds risk to your life.
> Diving is way less risky compared to skiing, driving (not to mention
> motorbiking) and even skateboarding. All this are accepted sports or tasks.
The perceived risk of getting out of bed just isn't there for most
people. The others that you mention are more likely to injure than
kill. Diving is a larger perceived risk for most people. Of the divers
that I know many drive motorcycles and fly air planes, more than in
other groups that I know.
> In my case, that is the mentioned 70bars. Given usually 200bars full
> tank. 50bar is 1 fourth of 200. Used for plain, warm dives.
In our case that's 1000PSI (1/3 tank) remaining. The plan is generally
to make it back to the mooring block, or close to shore on a shore
dive at 1000PSI. If there is something worth seeing we doddle around
until 800PSI (1/4 tank) or so before ascending. We then usually end up
at 700PSi at the surface. With most of my buddies that puts me at
1000PSI to 1100PSI at the surface.
When I have a buddy that's better on air. I plan to hit the surface at
500psi, but often get conservative on unfamiliar dives (or get bored
on familiar ones) and end up at 700PSI.
> Is that about 1 fourth or 1 third of full tank?
500PSI is 1/6th of a tank, even less for my 3200PSI tank.
> First, exactly _this_ was not my point. The 50bar-1/4 is rest, buffer,
> reserve. It is not used. Only for unforseen purpose/emergency/not
> whalesharks.
So even if you have an emergency at the bottom and end of a dive with
both divers sharing your tank, you've planned to surface with at least
1/4 tank?
> Second, "rise from depth" is way before reaching 50Bar. Depending on
> dive I plan and dive to be free of deko and in sight of ladder of boat
> at 50bar. On deeper dives due to safety/redundancy considerations this
> marker is set more to 70bar reserve.
There's one difference. The training I've had does not involve deco
diving. Safety stops only.
> I do not dive with panicking divers. If I dive with people who might
> have a slight chance to panic, I do not do any deep/blue. I do not do
> any tasks. I do have air for both of us and make shure that the diver is
> not panicking at all, period.
Replacing panicking with breathing hard, that's closer to what I
meant. It would take a heavy breathing diver and me on the same 1/6th
tank at 60ish feet to even come close to draining it. And that's
including a safety stop. Now 130+ foot dives are different, but then I
would be more conservative.
> I do not do "resort dives". It is more like "if we reach location, let
> my buddy and me go first and do not wait for us for supper".
Is this a terminology problem? I've been on dive boats run out of
resorts and operations that are standalone. They are quite similar in
their disregard for huge parts of the dive "standards" I was taught,
each in their own way.
> If they want to dive with me, I prefer asskicking. Otherwise they do not
> dive with me. I am setting the minimum standard. What others do, is not
> of my interest. They don`t have to care about me. I am fine, as long as
> they do not imply any rules of theirs on me.
I've heard a lot of divers say they are really tough on bad divers
similar to your "asskicking". I have yet to see that happen in the
wild. Perhaps in your case we simply don't cross paths, but I suspect
many might be exaggerating.
Should we be firm irm on other divers? Sure, I think bad divers need
to know when they've made a mistake, but not to the point of becoming
an "asskicking" jerk about it, I haven't seen a disgression worth that
yet.. So do you mean "asskicking" as really blowing up at the buddy or
just being firm?
John Van Ostrand
> In the nineties, a German company devellopped an autopilot device
> replacing your BCD`s inflator assembly providing automatic presettable
> depth and bouancy control, as well an ntegrated decompression
> including ascent feature following Buelmann's model.
I've often though that would be the "killer technology" (literally and
figuratively), but I didn't know it had been created. What killed it?
Lack of sales or lawsuits?
Greg Mossman
wrote:
> Should we be firm irm on other divers? Sure, I think bad divers need
> to know when they've made a mistake, but not to the point of becoming
> an "asskicking" jerk about it, I haven't seen a disgression worth that
> yet.. So do you mean "asskicking" as really blowing up at the buddy or
> just being firm?
I yell at Janna when I feel her buddy skills were lacking. (For
instance, when I've surfaced for whatever reason and she doesn't
follow for another half-hour.) I think it helps, but it probably just
wants to make her stab me sometime. That's why I don't let her dive
with a knife!
JRE
<snip>
> I'm told that BSAC, for example, include OW, AOW and rescue in the
> basic training. Were the skill requirements for original courses that
> deep?
Judge for yourself.
I was taught to do repetitive deco dives from US Navy tables in 1972.
It took Deco Procedures to catch me up to my "original" level of
training, excepting only accelerated deco using Nitrox, which did not
exist (perhaps outside commercial diving) at the time. Though I have
yet to take the class, much of the material in Rescue Diver was also
part of the basic course then.
Buddy breathing (no longer part of OW or AOW), doff and don (ditto), and
fitness tests all factored into the course. We were made to demonstrate
all skills (including doff, surface, dive, and don) in 20-25' (6-8m) of
water on our certification dives, which were shore dives in the Atlantic
with surf entry and exit. We had to know our SAC rates and be able to
put together a gas plan--without SPGs, which were rate. We had to
demonstrate buoyancy control with mouth-inflated horse collars.
If I recall correctly, the course ran about three months twice a week
with time split between classroom and pool, followed by two open water
certification dives.
Having said that, the equipment, training, and techniques for diving are
*vastly* superior today, and the level of training we got back then for
an OW cert (there was no other kind) was far beyond what is necessary
for safe recreational diving within the NDL in my opinion. Back then,
you were either a diver, or not a diver. Lots of people died learning
how to extend the sport into places like wrecks, caves, and depths much
beyond 250' with some degree of safety. I don't want to go back.
Though I have an opinion about the level of training given for
"advanced" OW it seems clear that the incremental approach works as well
or better for most people, and I suspect many would be deterred by the
Navy-style training regimen from the early 70's. Much more training is
available now, it's just in smaller bites. On the balance, I think
that's better, though I would plump for more skills I consider basic to
be included much earlier in training--in particular, gas planning.
--
John Eells
Dan Bracuk
<john.van...@gmail.com> wrote:
>I've often though that would be the "killer technology" (literally and
>figuratively), but I didn't know it had been created. What killed it?
>Lack of sales or lawsuits?
Probably lack of sales due to general uselessness.
Dan Bracuk
wrote:
>You, always benefitting. Your SAC sucks, Hanna`s doesn`t ;-)
Doesn't seem too wrong to me.
Dan Bracuk
<alan....@FreelunchVideotron.ca> wrote:
>In that case my buddy will always be my SO! When I'm at 600 she's at
>1400. A friend indeed! If I ever manage to tame my air consumption,
you'll change your opinion about computers.
Dan Bracuk
wrote:
>You plan your dive. You dive your plan.
You might, I don't.
I jump in and react to what's there. I look at my watch, spg, and
computer for useful information that helps me decide how long to stay
down. Sometimes I simply follow the group.
Dan Bracuk
>Why, necessarily? If one diver continually runs short on air and his
>buddy continually returns with more air than the recommended minimum,
>assuming only one size tank is available such as at the standard
>resort setting, what's the harm in balancing out the air a bit if it
>can prolong the dive by another few minutes?
Absolutely nothing.
Dan Bracuk
Which shows how unnecessary that knowlege is.
Curtis
>> Most divers have no idea of their SAC rate,
> Which shows how unnecessary that knowlege is.
Beg to differ.
Although the specific numbers may not be important, knowing how long a
tank will last is.
Curtis
Curtis
"Dan Bracuk" wrote
>>Why, necessarily? If one diver continually runs short on air and his
>>buddy continually returns with more air than the recommended minimum,
>>assuming only one size tank is available such as at the standard
>>resort setting, what's the harm in balancing out the air a bit if it
>>can prolong the dive by another few minutes?
> Absolutely nothing.
If the sharing is done early, before reserves are hit, gotta agree,
although I'd not advise a newbie to do it.
(Opinion limited to recreational OW diving.)
Curtis
Curtis
I won't.
Unnecisary evil, undesireable luxury, waste of dive funds.
Curtis
Joerg Hahn
> I jump in and react to what's there. I look at my watch, spg, and
> computer for useful information that helps me decide how long to stay
> down. Sometimes I simply follow the group.
Sounds like a plan to me ;-)
Scott
news:4b74e500$0$4943$9a6e...@unlimited.newshosting.com...
>> you'll change your opinion about computers.
> I won't.
> Unnecisary evil, undesireable luxury, waste of dive funds.
Insurance company lawyer driven algorithm.
MatV
wrote:
> On 10-02-11 13:16 , MatV wrote:
>
>
>
> > On Feb 10, 10:44 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca>
> > wrote:
> >> On 10-02-10 4:09 , Geoff wrote:
>
> >>> Awareness. Awareness. Awareness.
>
> >>> You don't dive a profile waiting for a bell to ring like you're a
> >>> three minute egg.
>
> >> I never said different, in fact I mentioned the scenario above as a
> >> negative in the idea - complacent dependency.
>
> >> But I stand on the notion that given how important air alone is to the
> >> whole enterprise that a backup warning is merited for those who may from
> >> time to time get otherwise distracted.
>
> > In commercial scuba appliances a double independant pressure control
> > is obligatory. One is to function in no vis environments.
>
> I'm talking about a passive warning device, not a control.
I don't want to dive into kybernetics, but I am speaking of passive
and active devices. The pointer of a gauge is controlled by the
pressure. Same is the shutting action of a mechanical reserve valve,
or a beep at the dive computer. For no viz dives, Draeger FFMs have
the "pecker", something which vibrates againts your cheek.
Matthias
MatV
wrote:
Well I don't know exactly if it is still in production. Methinks the
company had seen severe economic difficulties. This was long ago, I
believe in the early Nineties. It was before the arrival of the Uwatec
Nitrox range of computers.
In a medical meeting 3 years ago, a paraplegic was speaking about how
he is using this device, and some incredible fins mounted at the lower
arm, while still allowing full hand motion range if needed.
I'll try my best to remember the name of the device. The creator last
name was Tolksdorf, I believe, but probably not the same one as the
guy from Tecme.
Matthias
Joerg Hahn
John Van Ostrand wrote:
> It's not that economy is the goal, but, regardless of how or why
> people dive safely the more that dive the more choices divers have.
I`m getting your point. Here in my homeland they close freshwater lakes
because of too much divers. So the divers acumulate at the remaining
lakes and the overcrowding still gets worse.
> people. The others that you mention are more likely to injure than
> kill. Diving is a larger perceived risk for most people.
In my homeland, you have way more killed bikers and the social
healthcare has vastly higher costs by killed and injured skateboarders.
>> In my case, that is the mentioned 70bars. Given usually 200bars full
>> tank. 50bar is 1 fourth of 200. Used for plain, warm dives.
>
> In our case that's 1000PSI (1/3 tank) remaining. The plan is generally
> to make it back to the mooring block, or close to shore on a shore
> dive at 1000PSI. If there is something worth seeing we doddle around
> until 800PSI (1/4 tank) or so before ascending. We then usually end up
> at 700PSi at the surface. With most of my buddies that puts me at
> 1000PSI to 1100PSI at the surface.
If you do ndl dives in warm water 1/3 tank reserve is _very_
conservative. 1/4 at mooring is ok.
>> First, exactly _this_ was not my point. The 50bar-1/4 is rest, buffer,
>> reserve. It is not used. Only for unforseen purpose/emergency/not
>> whalesharks.
>
> So even if you have an emergency at the bottom and end of a dive with
> both divers sharing your tank, you've planned to surface with at least
> 1/4 tank?
That is not what I said.
Emergency is end of dive, is ascend, is get out the water.
The outcome of an emergency situation is not planable.
What you can plan is: figure out what might happen, increase your
chances by more air/reserve, more skills, more equipment, different
equipm., better equipm, more briefing....
> There's one difference. The training I've had does not involve deco
> diving. Safety stops only.
And at dives with safety stops you don`t have decompression?
The truth may hit you hard, even recreational diving and so called NDL
dives do have dekompression in ascend. And the gas needs to go
somewhere. Whether you call it safety stop or deko stop.
Same thing happening there.
> Replacing panicking with breathing hard, that's closer to what I
> meant. It would take a heavy breathing diver and me on the same 1/6th
> tank at 60ish feet to even come close to draining it.
I would consider to do those dives without a tank.
You don`t need a safety stop then either. ;-)
> Now 130+ foot dives are different, but then I
> would be more conservative.
I daubt, you do a decent NDL safety stop dive on 130+ft.
But right, 180 to 240ft on air is different.
>> I do not do "resort dives". It is more like "if we reach location, let
>> my buddy and me go first and do not wait for us for supper".
>
> Is this a terminology problem?
Probably.
> I've heard a lot of divers say they are really tough on bad divers
No, I am not. I am not there.
> Should we be firm irm on other divers?
I don`t care. Those are not diving with me.
> just being firm?
When they dive with me, they want to learn. Then I am firm.
Or they dive with me on an equal basis. Then they don`t fool around and
I regard them as friends. And I don`t dive with spousses.
Greg Mossman
No, not something newbies should be advised to do. It requires enough
trial and error experience to know how far you can safely "cheat".
Also something that is done later than earlier in the dive, when we
both have a better sense of how close we our to our "reserves" and
when we're likely to be shallower and therefore closer to the surface
and unlimited air just in case we cut it too close.
In Bonaire, for instance, it's allowed us to make it back from the
second reef to the first without having to make a lengthy surface
swim. Plenty of reserve left in my tank if we needed to make an
emergency ascent from 70-80 feet, even including safety stop (700 psi
is plenty for that), so why not suck her 1,200 psi down a bit while
making the swim at depth, thus allowing both of us to ascend up the
gentle slope of the first reef from 60' with about 700 psi left
apiece, 500 left at the 25' crest of the reef, and 350 when we finally
end up in waist-deep water and come up for good. Now that's a dive
plan!
Alan Browne
> John Van Ostrand wrote:
> <snip>
>> I'm told that BSAC, for example, include OW, AOW and rescue in the
>> basic training. Were the skill requirements for original courses that
>> deep?
>
> Judge for yourself.
>
> I was taught to do repetitive deco dives from US Navy tables in 1972. It
> took Deco Procedures to catch me up to my "original" level of training,
> excepting only accelerated deco using Nitrox, which did not exist
> (perhaps outside commercial diving) at the time. Though I have yet to
> take the class, much of the material in Rescue Diver was also part of
> the basic course then.
>
> Buddy breathing (no longer part of OW or AOW),
We did buddy breathing in the pool for the PADI OW. In fact we did this
on a 'tourist' dive in Cancun in 2003 as well.
> doff and don (ditto), and
If you mean the mask, of course we did that in the pool and in the OW
dives. Our instructor also had a fetish for putting on equipment in the
water.
> fitness tests all factored into the course. We were made to demonstrate
> all skills (including doff, surface, dive, and don) in 20-25' (6-8m) of
> water on our certification dives, which were shore dives in the Atlantic
> with surf entry and exit. We had to know our SAC rates and be able to
> put together a gas plan--without SPGs, which were rate. We had to
> demonstrate buoyancy control with mouth-inflated horse collars.
We didn't do buoyancy control with our BCD mouth valve (though I can't
see that as hard, just cumbersome), we did runaway BCD hose
disconnection while holding the BCD purge valve open.
> If I recall correctly, the course ran about three months twice a week
> with time split between classroom and pool, followed by two open water
> certification dives.
>
> Having said that, the equipment, training, and techniques for diving are
> *vastly* superior today, and the level of training we got back then for
> an OW cert (there was no other kind) was far beyond what is necessary
> for safe recreational diving within the NDL in my opinion. Back then,
> you were either a diver, or not a diver. Lots of people died learning
> how to extend the sport into places like wrecks, caves, and depths much
> beyond 250' with some degree of safety. I don't want to go back.
>
> Though I have an opinion about the level of training given for
> "advanced" OW it seems clear that the incremental approach works as well
> or better for most people, and I suspect many would be deterred by the
> Navy-style training regimen from the early 70's. Much more training is
> available now, it's just in smaller bites. On the balance, I think
> that's better, though I would plump for more skills I consider basic to
> be included much earlier in training--in particular, gas planning.
The PADI OW cert thence to other grades seems really adapted to the
tourism cycle. You can do the OW in a 1 week trip south and even add
another boy scout badge while there. On other trips you can add a
couple more boyscout badges each time.
What I found bizarre was the insistence that we watch the PADI videos
which were thin gruel compared to the manual. As my SO and I each read
the manual (250 p) cover to cover, we each scored 100% on both written
tests to the surprise of the instructor. I guess a lot of people write
the exam based on the videos alone. Scary. (The videos don't go into
the tables at all, you have to learn that from the table manual).
Gas planning for the lowest levels seems to be "so, how long do you
think a tank will last at 60'"?
Answer: "if my SO is with me, it'll last 10 minutes longer."
Alan Browne
All I mean by passive is something that requires no active component, no
power (other than the air pressure in hoses) is not in the way of air
flow to the diver or the gauge and if it fails, it fails in a way that
will not affect the gauge nor of course the air flow to the diver.
Dan Bracuk
wrote:
> If the sharing is done early, before reserves are hit, gotta agree,
>although I'd not advise a newbie to do it.
>
> (Opinion limited to recreational OW diving.)
In real life, you won't know that the sharing requirement is there
until it comes up, which is later on in the dive.
Since the option is limited to recreational OW diving only, the
concept of reserves basically means, "can we make it to the surface?".
Dan Bracuk
wrote:
> Beg to differ.
>
> Although the specific numbers may not be important, knowing how long a
>tank will last is.
Begging is so unbecoming. I choose to differ.
It's possible to know long a tank will last without knowing your SAC.
Curtis
"Dan Bracuk" wrote
>> Beg to differ.
>>
>> Although the specific numbers may not be important, knowing how long a
>>tank will last is.
> Begging is so unbecoming. I choose to differ.
Aye, literally meant it is, but recognizing your experience is my
choice.
> It's possible to know long a tank will last without knowing your SAC.
Quite true, and actually the important concept.
Curtis
Curtis
"Dan Bracuk" wrote
> In real life, you won't know that the sharing requirement is there
> until it comes up, which is later on in the dive.
>
> Since the option is limited to recreational OW diving only, the
> concept of reserves basically means, "can we make it to the surface?".
"Can WE make it _safely_ to the surface at any time sharing either one
gas supply?"
Curtis