Thank you.
Down deep...things to remember
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Ayisha
Contributor
Yes, it has been said well. It makes me re-think my (very basic) gear set-up. I have always used a 63 cf tank. That's it. I am a petite woman who somewhat struggles carrying a 63, and really struggles with an 80 cf tank. If an 80 tank is not put extremely low in my BCD straps (top strap ON the curve), it will hit my head throughout the dive and the valve will push my mask strap off. I have had huge goose eggs on the back of my head from doing a giant stride with the tank not exactly perfect (essentially not using the top strap). If it is low enough to not hit my head, my legs bang the tank (but that hurts less). :icorolley
I have none of these problems with a 63. I use very little air (people say I breathe like a bird and leaders are always surprised at how much air I have left when they check). I normally come back with 1500 psi (starting from about 2800 - 3000 psi) and at worst 1000 psi from any dive, with maximum bottom time, even for very cold (38 F) and deep (80 - 130 ft) dives. I can do two very cold deep dives on one 80 tank and still come back with 1000 psi. I don't think these figures are unusual for petite women who are properly weighted and therefore not struggling.
So, since I always come back with 1/3 to 1/2 of my air supply, is this enough? Perhaps not for my buddy's potential emergency? My LDS owner has told me in the past that I could probably use a 50 cf most of the time, but a 63 gives me contingency air. In Cozumel last year, the LDS owner also said I should just go with a 50 instead of 72 since I kept coming back with almost 2000 psi compared to some peoples 500 (with 80's), but the next dive was Punta Sur and I didn't want to chance it or have time to play with my weighting. So what do you guys think? Is it enough contingency air (even though it's not redundant) for a small person considering my horrible experiences with 80's? :scared:
I have none of these problems with a 63. I use very little air (people say I breathe like a bird and leaders are always surprised at how much air I have left when they check). I normally come back with 1500 psi (starting from about 2800 - 3000 psi) and at worst 1000 psi from any dive, with maximum bottom time, even for very cold (38 F) and deep (80 - 130 ft) dives. I can do two very cold deep dives on one 80 tank and still come back with 1000 psi. I don't think these figures are unusual for petite women who are properly weighted and therefore not struggling.
So, since I always come back with 1/3 to 1/2 of my air supply, is this enough? Perhaps not for my buddy's potential emergency? My LDS owner has told me in the past that I could probably use a 50 cf most of the time, but a 63 gives me contingency air. In Cozumel last year, the LDS owner also said I should just go with a 50 instead of 72 since I kept coming back with almost 2000 psi compared to some peoples 500 (with 80's), but the next dive was Punta Sur and I didn't want to chance it or have time to play with my weighting. So what do you guys think? Is it enough contingency air (even though it's not redundant) for a small person considering my horrible experiences with 80's? :scared:
You've asked a very good question Ayisha... and also recognized an important point... your *contingency* gas needs to take into account your buddy's consumption.
Knowing your own normal SAC and doubling it for emergencies is not unreasonable. Knowing your buddy's normal SAC and doubling that is also not unreasonable when figuring emergency gas requirements.
For your non-overhead non-deco OW recreational diving you would ideally reserve enough gas that both you and your buddy could ascend from the the deepest portion at 30fpm and make your 3 minute safety stop at 15' while using only your gas supply.
This contingency gas is often called Rock Bottom.
We have some excellent posts already on ScubaBoard on figuring SAC as well as figuring Rock Bottom reserve.
Knowing your own normal SAC and doubling it for emergencies is not unreasonable. Knowing your buddy's normal SAC and doubling that is also not unreasonable when figuring emergency gas requirements.
For your non-overhead non-deco OW recreational diving you would ideally reserve enough gas that both you and your buddy could ascend from the the deepest portion at 30fpm and make your 3 minute safety stop at 15' while using only your gas supply.
This contingency gas is often called Rock Bottom.
We have some excellent posts already on ScubaBoard on figuring SAC as well as figuring Rock Bottom reserve.
Ayisha, UP already made a good point. The tank size you currently use is probably sufficient for most OW recreational dives. But it may not be enough if either you or your buddy's reg fails at 130" (specifically your buddy's) and both of you have to get back to the surface, especially since that will probably cause at least a minimal amount of panic with increased SAC. Something like Spare air may come in handy for you. It's compact and lightweight and it provides you with a redundant source. I have never dived with one and have heard that it only gives you enough air to ascend from about 60' (average SAC) and generally don't recommend it. But it might be worth looking into for someone like you with a low SAC rate to begin with. I have read threads on this here at SB as well.
Who are you and what have you done with Uncle Pug?Uncle Pug:
LOL!! This is the Uncle Pug I met in person over a year ago.... The answer a question with a riddle to make you think guy disappeared! He answered my naive questions with answers that made sense and didn't ridicule me for my ignoranceOneBrightGator:
On the other hand - he made some pretty pointed statements to others (in my presence) about pony bottles that made me.... well.... uh... reconsider :11:
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Switching to a steel tank would probably help.
A Faber steel 80 is 6 inches shorter than an aluminum 80.
Terry
A Faber steel 80 is 6 inches shorter than an aluminum 80.
Terry
Dive-aholic:
Ayisha
Contributor
Thanks guys.
So if my buddy's a hoover, I'd better use an 80... :11ztongue I tend not to repeat THOSE kinds of buddies...
Most of my usual buddies are instructors/leaders and tend to use their huge Nitrox doubles while I use my 63. They haven't had an issue with this or they would tell me in no uncertain terms. I guess it doesn't matter to them because I'm not part of their contingency plan - they're self-reliant - and they can take care of a few other people. Some of them also use full tech gear, but not with me. When I do light penetrations with them or extra special wrecks around here, I use a Nitrox 80 (only because I rent the Nitrox tanks, and I haven't found any smaller rental Nitrox tanks. I curse under my breath, but now I realize the 80's were a good thing for overhead environments). But when I have buddies that aren't as self-reliant, I will definitely have to think about that...
Thanks for all the tips!
Webmonkey, I believe a shorter 80 steel tank would solve my problem. Thanks!
BTW, it seems that Uncle Pug can be quite a sweetie when he wants to be... :10:
So if my buddy's a hoover, I'd better use an 80... :11ztongue I tend not to repeat THOSE kinds of buddies...
Most of my usual buddies are instructors/leaders and tend to use their huge Nitrox doubles while I use my 63. They haven't had an issue with this or they would tell me in no uncertain terms. I guess it doesn't matter to them because I'm not part of their contingency plan - they're self-reliant - and they can take care of a few other people. Some of them also use full tech gear, but not with me. When I do light penetrations with them or extra special wrecks around here, I use a Nitrox 80 (only because I rent the Nitrox tanks, and I haven't found any smaller rental Nitrox tanks. I curse under my breath, but now I realize the 80's were a good thing for overhead environments). But when I have buddies that aren't as self-reliant, I will definitely have to think about that...
Thanks for all the tips!
Webmonkey, I believe a shorter 80 steel tank would solve my problem. Thanks!
BTW, it seems that Uncle Pug can be quite a sweetie when he wants to be... :10:
So, are all you anti tank-hangers ready to hang yet??
Surely you have seen the light!
Wish I could've "hung" on for your capitulation, but the Mrs. threatened to "hang" me out to dry if I didn't "hang" up on this thread!
What? You're still not hung?
Are you HUNGry for more debate!
O.K. - what if I promised you naysayers a free "T"...
How about:
* "Hang one for the team!"
* "Hang em' high or Hang em' low, when the supply is dry its where ya go!"
* "When in danger or in doubt, trip on down to the "HANGout!"
(Yawn)...time to hang em' up.
Quick quip: Why are the Brits. teeth in such sorry shape? Too many meals of "Hangers n' Mash".
Bye y'all!
D.S.D.
Surely you have seen the light!
Wish I could've "hung" on for your capitulation, but the Mrs. threatened to "hang" me out to dry if I didn't "hang" up on this thread!
What? You're still not hung?
Are you HUNGry for more debate!
O.K. - what if I promised you naysayers a free "T"...
How about:
* "Hang one for the team!"
* "Hang em' high or Hang em' low, when the supply is dry its where ya go!"
* "When in danger or in doubt, trip on down to the "HANGout!"
(Yawn)...time to hang em' up.
Quick quip: Why are the Brits. teeth in such sorry shape? Too many meals of "Hangers n' Mash".
Bye y'all!
D.S.D.
D.S.D., do you hear the lynch mob getting ready to HANG :hanged: you?
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