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Reply to: Re: Wetsuit+single steel tank, fresh water diving / =
DIR
Kevin...
One question. In the example you gave using the AL tanks, you said:
<snip>
Backplate, light -11
Double 80's, +4 empty each, -8 full for the set(nitrox)
Two 40's, 0 empty, -3 full each, -6 for two
<unsnip>
and
<snip>
it looks like you need about 28 lbs to sink your wetsuit (which is about =
what =
I need to sink my drysuit in this balmy 47F water)
<unsnip>
and
<snip>
plus, say a weightbelt of 12lbs
<unsnip>
Isn't it true then, with that config, that you would be =
(-11+8+0-12+38)=3D23 pounds positive at the end of the dive?
Isn't that a tad too positive?
Just trying to learn
Regards,
JohnnyH
Kevin Connell wrote:
>Parrots must be relatively good at math then. =
>
>Let's take a best case scenario for steel tanks, maybe hp100's, somewhere
>around neutral when empty, 15 some odd pounds of nitrox, less for mix.
>You've also got 4 lbs on your back plate and maybe 7lbs on the light.
>Thats 26lbs negative at the bottom, at the beginning of the dive, backgas
>only.
>
>Now add two steel hp80'so for tanks for deco, surely the choice of =
someone
>wearing hp's for doubles. (Not to mention one of them is filled with 80%)=
>They are about 2-4lbs neg each when empty, plus 12 lbs of strokemix full
>(for both). That's another at least 16 lbs negative at the start of a =
dive.
>
>Since you've only got 7+4+2+2 =3D 15lbs empty negative weight here, and =
it
>looks like you need about 28 lbs to sink your wetsuit (which is about =
what
>I need to sink my drysuit in this balmy 47F water), you'll need 13lbs on
>your belt.
>
>That leaves us with 26+16+13 =3D **55lbs** negative at the beginning of =
the
>dive.
>
>Can you swim that up? Maybe, not very easily, especially with the =
obvious
>choice of force fins, at this point, and given the 80's for deco, you'll
>run out of gas within about 2 minutes ;)
>
>Murder by numbers.
>
>Now, contrast that with GI's perspective (not mine..)
>
>Backplate, light -11
>Double 80's, +4 empty each, -8 full for the set(nitrox)
>Two 40's, 0 empty, -3 full each, -6 for two
>
>That's a total of -25 for the entire thing, plus, say a weightbelt of
>12lbs (guessing here, incl 8lbs positive tanks for ditching purposes),
>gives you -37 at the bottom, start of dive. That's a savings of 18lbs
>(40%) of weight.
>
>Now I may have mixed up or omitted some stuff, but the gist is steel =
tanks
>and deco bottles are too damn negative.
>
>Seems to add up to me, "Polly want a cracker?"
>
>No redundant bladder replies, please.
>
>
>At 8/13/1998 -0500, s_lindblom@co*.co* wrote:
>>>I was wondering whether a
>>>single steel tank with backplate, wing and wetsuit would be safe to =
dive in
>>>fresh water conditions.
>>
>>
>>This is the problem with the authoratarian "Since X is a much better =
diver
>>than you, you should accept the word of those who claim to be speaking =
for
>>him without question" method of achieving safety being promogulated by =
some
>>on this forum.
>>
>>When people speak of steel tanks being dangerous with wetsuits, they are
>>referring to DOUBLES of the PST 95 and 104 genre, very heavy tanks, and
>>they are right in this regard. However, there are a lot of other wet/=
steel
>>configurations out there that work just fine, and must be considered on =
a
>>case-by-case basis, Which is why it is good to be able to figure these
>>things out for yourself, as you are doing, rather than defer to some
>>improperly understood or misapplied rule.
>>
>> I dive wet fairly regularly with a single Faber 95. Even using a SS
>>backplate with some extra weight in the valley, I still need 18 lbs on =
my
>>belt, in saltwater, which I figure is enough ditchable weight for the
>>depths I dive this config (in freshwater I leave off the backplate =
weight).
>>With light doubles - 72's or 85's - I start getting into the gray area, =
so
>>I would use an alu plate, which puts another 6 lbs on my belt.
>>
>>Historically, it is funny to note how for a long time all the parrots on
>>this group were for ever so long telling anyone who would listen that =
the
>>ONLY tanks to use were LP steels. Then George casually mentioned one day
>>that he dove alu when wet. When the shock cleared, suddenly the same =
parrot
>>chorus that had been yelling that anything but LP steels were the mark =
of a
>>stroke began yelling that only strokes dove steel wet. Yet the physical
>>laws regarding bouyancy were the same before he spoke as after.
>>
>>That's the problem with an authoritarian system, where you cannot freely
>>question and dispute the authority, especially when that authority is
>>capricious. No matter how much that authority might know, if the =
authority
>>doesn't happen to mention the tidbit of info you need when you need it, =
you
>>may be out of luck.
>>
>>It's not enough to follow rules - you have to understand the logic =
behind
>>them, so you can deal with situations that the rules don't cover. That's
>>why is serves no one to stifle discussion here, and why those, like Dan,
>>who would are just plain wrong.
>>
>>
>>
>>
>>--
>>Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
>>Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
>>
>>
>--------------------------------------------------
>Kevin Connell <kevin@nw*.co*>
>
>Northwest Labor Systems
>http://www.nwls.com
>Lake Stevens, WA
>
>--------------------------------------------------
>--
>Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
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>Date: Fri, 14 Aug 1998 10:36:55 -0700
>To: s_lindblom@co*.co* (Steve Lindblom)
>From: Kevin Connell <kevin@nw*.co*>
>Subject: Re: Wetsuit+single steel tank, fresh water diving / DIR
>Cc: techdiver@aquanaut.com
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