SparticleBrane
Contributor
I've never had a boat crew check my SPG...howarde:
What pressure to end a dive? A debate!
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I never have either. But some say they will...SparticleBrane:
Most of the charters I dive on stay out of my business, my dive planning and my gas planning and that's the way it should be. I was on a boat once where the DM anounced in a big loud voice that anyone who surfaced with less than 500 psi remaining wouldn't be allowed to dive again.
I understand that they are trying to force divers who don't know anything about planning gas to have some reserve (though 500 psi may not be enough). The problem with this is that my reserve isn't to make the DM happy. It's to USE in the case someone has a problem. If I use my reserve to bail someone out of an equipment failure, then that gas was used correctly for the purpose it was intended. I hate to say it but if the bum wouldn't let me dive again because I saved someones bacon, I would have to mutiny and make him walk the plank. Or...maybe I should keep my reserve for makiong the DM happy and I get to dive again by refusing to give gas to someone who needs it. Let the sucker drown...I aint gettin in trouble!
You don't need the gas on the boat. You need gas to get to the boat.
I understand that they are trying to force divers who don't know anything about planning gas to have some reserve (though 500 psi may not be enough). The problem with this is that my reserve isn't to make the DM happy. It's to USE in the case someone has a problem. If I use my reserve to bail someone out of an equipment failure, then that gas was used correctly for the purpose it was intended. I hate to say it but if the bum wouldn't let me dive again because I saved someones bacon, I would have to mutiny and make him walk the plank. Or...maybe I should keep my reserve for makiong the DM happy and I get to dive again by refusing to give gas to someone who needs it. Let the sucker drown...I aint gettin in trouble!
You don't need the gas on the boat. You need gas to get to the boat.
Diver Dennis
Contributor
I see DMs checking gauges all the time under water in some places I dive, which are resort situations where they get a lot of 5 to 10 dive a year clients.
MikeFerrara:Most of the charters I dive on stay out of my business, my dive planning and my gas planning and that's the way it should be. I was on a boat once where the DM anounced in a big loud voice that anyone who surfaced with less than 500 psi remaining wouldn't be allowed to dive again.
I understand that they are trying to force divers who don't know anything about planning gas to have some reserve (though 500 psi may not be enough). The problem with this is that my reserve isn't to make the DM happy. It's to USE in the case someone has a problem. If I use my reserve to bail someone out of an equipment failure, then that gas was used correctly for the purpose it was intended. I hate to say it but if the bum wouldn't let me dive again because I saved someones bacon, I would have to mutiny and make him walk the plank. Or...maybe I should keep my reserve for makiong the DM happy and I get to dive again by refusing to give gas to someone who needs it. Let the sucker drown...I aint gettin in trouble!
You don't need the gas on the boat. You need gas to get to the boat.
Exactly (I've heard DM's announce it as well - although they've never bothered me) --- I think they say that for the benefit of newer divers (or like dennis is referring to, the "average vacation diver") who need to be reminded about safety issues for the safety of the continued existence of the dive charter.
Diver Dennis
Contributor
I agree Mike and howarde.
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Nothing occurs in a vacuum. The old J-valves held back a 300 psi reserve, thus when SPGs came out that number was carried forward. When the Steel 72 was replaced with an aluminum 72 (and the pressure raised to 3000 psi) then the reserve pressure was raised (both operationally and with new springs for J-valves) to 500 PSI. So the numbers came from somewhere (even if the operators today don't have a clue where). To my way of thinking getting back on the boat with 500 PSI may be foolish, it maybe far better to burn that down to 200 psi at 15 feet under the boat, that's "in case" gas ... which is good to have, "in case." Rock Bottom (as the DIRs call Bingo Air, a term that's been used in the science community since before the first time the DIRs wore diapers) is a much more detailed approach to gas planning that IMHO should be taught in every entry level course.
howarde:
Right on the money...A good DM won't bench a diver because they came up with less than 500 psi. If the diver can be identified as a newbie or a 5-10 dives per year diver, a good DM should offer a some insight on how to maximize bottome time and still come up with 500psi. If they're a veteran diver and/or I'm reasonably confident of their abilities, I don't worry about it too much.
Oriskany Divemaster:
A good DM will explain to the new diver how to determin what an adequate reserve is for the planned dive. A reserve of 500 psi might be enough for some dives but not for anything that's very much of a dive. When they start throwing around arbitrary numbers they just let everyone know that they don't know what they're talking about. Charters that employ DMs who don't know what they're talking about should be avoided.
MikeFerrara:
I couldn't agree with you more. So many times large cattle boats have such diverse divers aboard at any given time, the experienced suffer because of the DM's need to reach the new divers.
But getting the new guys back on the boat with 500psi is a good place to start. If a diver says, "I'm going to be diving X profile which will put me back at the surface with 350psi," I'd reply with, "Have a great dive." By that one statement, he's telling me he's done his planning. But I have the luxury of diving from a small, fast boat and we can be a little more flexible when it comes to profiles.
Also, on a lot of boats, the 500psi limit is the captain's call, and the DMs are just the messengers.
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