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How did we get from diving a single steel tanks with a wet suit to diving with 3 tanks (regardless of the mix)? If you've only got 100cf of back gas, what do you need 160cf of deco gas? Why would you be doing a dive with a single that required 2 deco gases? This I would think is a real stroke action, more so than the 80%? Why did we get off topic, just feel like saying something and beating the old dead horse? I don't dive HP 100's but I don't think they are quite 15 lbs. full. Maybe I'm wrong (and I'm sure I'll be corrected) but I see people all the time who are fit and diving dry suits with double 100's and 15 lbs. on the belt. Using this math, that's a lot of weight at the surface. Assuming the belt weight is selected to be relatively neutral and comfortable during the hang, they don't seem to sink like they have extra 30lbs on? Yes in balmy 35 degree water with Thinsulate (winter) Art. -----Original Message----- From: Kevin Connell [SMTP:kevin@nw*.co*] Sent: Friday, August 14, 1998 1:37 PM To: s_lindblom@co*.co* Cc: techdiver@aquanaut.com Subject: Re: Wetsuit+single steel tank, fresh water diving / DIR 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 = 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 = **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'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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