Split from A&I Yukon thread: Gas Rules in OW Solo Dives

[Thalassamania]

... The size of tank isn't relevant here; when you hit your low gas mark, you end the dive. On an AL80 at 100' that should be about 1000psi, although 500 would be enough to do your safety stop and surface if you're solo

Why on earth would that be at about 1000psi? Especially if you're diving solo and don't have to have gas for a buddy?

You another guy that size doesnt matter! well dive with a 50cf then. I get the small point you are making that no matter what size you must return b4 u run out. Thats where the pony comes in. whatever happend to 1/3 1/3 1/3 on the planning? they not teaching that to you guys now?

When did the rule of thirds become applicable to a no ceiling, open water diver?

 

[Jax]

Why on earth would that be at about 1000psi? Especially if you're diving solo and don't have to have gas for a buddy?
When did the rule of thirds become applicable to a no ceiling, open water diver?

SDI teaches the rule of thirds in their solo diving class.

 

[Blackwood]

When did the rule of thirds become applicable to a no ceiling, open water diver?

This. For open water diving, I'm hard pressed to come up with a realistic situation where I'll use as much gas ascending as I did descending and on the bottom.

 

[Thalassamania]

SDI teaches the rule of thirds in their solo diving class.

I've never really thought out gas management for solo diving. What is SSI's reasoning? I hope it is something better than, "just in case."

 

[Jax]

I've never really thought out gas management for solo diving. What is SSI's reasoning? I hope it is something better than, "just in case."

1/3 out, 1/3 up, 1/3 for emergencies. You never include your redundant gas in the planning.

One third out, coming back you get entangled . . . you are now breathing your emergency third while cutting yourself loose. Then you are back on your third to get up and out.

The pony should be one third of your gas supply, so if you have a catastrophic failure of your back gas, the pony gets you up.

If it makes you feel any better, I absolutely hate climbing out with a 1000 psi! :chuckle:

BTW, I highly recommend the solo class for newer divers only in that it puts you in another frame of mind of diving. I took it because I have one of those same ocean, same day buddies.

 

[Thalassamania]

1/3 out, 1/3 up, 1/3 for emergencies. You never include your redundant gas in the planning.

One third out, coming back you get entangled . . . you are now breathing your emergency third while cutting yourself loose. Then you are back on your third to get up and out.

The pony should be one third of your gas supply, so if you have a catastrophic failure of your back gas, the pony gets you up.

If it makes you feel any better, I absolutely hate climbing out with a 1000 psi! :chuckle:

BTW, I highly recommend the solo class for newer divers only in that it puts you in another frame of mind of diving. I took it because I have one of those same ocean, same day buddies.

Thanks, that doesn't sound very well thought out, IMHO. 1/3 out 1/3 up is, I think, way over the line to idiotic unless there is a ceiling, since straight up to air is, by definition, at most 7 minutes away. I can see holding back a bit (how much I'd have to think about) for "emergencies," but that will wind up being arbitrary and always too much or too little.

 

[Blackwood]

1/3 out, 1/3 up, 1/3 for emergencies. You never include your redundant gas in the planning.

What type of dive profiles require as much gas to ascend as you use on the bottom (1/3 out, 1/3 up)?

Is that a conservative gas plan? Yah, absolutely. But are there appropriately reasonable assumptions backing it up? I'm not so sure. It seems more like they heard that cave divers do it so it must work. But cave divers generally dive the same profile out as they do in (so that equal gas assumption makes more sense).

 

[Thalassamania]

I just wanted to make sure that I was not missing something. I never dive solo, so I've never bothered to think solo diving gas management through ... kinda sounds like SDI hasn't exactly thought it through either. I have less and less respect for the recreational diving world each day.

 

[muddiver]

I just wanted to make sure that I was not missing something. I never dive solo, so I've never bothered to think solo diving gas management through ... kinda sounds like SDI hasn't exactly thought it through either. I have less and less respect for the recreational diving world each day.

Yep, that course got me into a roundabout argument over the difference between SAC and RMV. I'm not overly impressed with the little book that come with the course. There are a lot of major descepancies in it.

 

[Jax]

Exactly ... it sounds like a gas management plan that was not thought out.

It's not locked into a third out and a third in . . . you plan your dive and the gas to it. But yes, they recommend planning use of only two thirds.

Yep, that course got me into a roundabout argument over the difference between SAC and RMV. I'm not overly impressed with the little book that come with the course. There are a lot of major [-]descepancies [/-] discrepancies in it.

Don't know how that could happen . . .

Is that the new book, 2009, I think? I was told mine was a new book.