High SAC rate and low SAC rate

[Pavão]

So, who should carry the larger set of doubles? The diver with the higher sac rate or the one with lower sac rate?

I would put the higher sac rate diver on larger tanks.

The argument against this is that it would put the team further into the cave and if higher sac rate diver were to loose all gas, there wouldn't be enough gas for both to come out.
I thought that when matching tanks(dissimilar tanks), it eliminates that problem, no?

What am I missing here?

[Mark Vlahos]

It should not matter because you should cylinder match to the gas used in the smaller tanks.

Mark Vlahos


Sent from my iPhone using Tapatalk

[Sludge]

What am I missing here?

That when you compensate for dissimilar cylinders they will turn when his buddy just barely has enough gas for the both of them.

[Sabado]

That when you compensate for dissimilar cylinders they will turn when his buddy just barely has enough gas for the both of them.

That's assuming the lower sac rate diver with the smaller tanks calls it on thirds.

[Sludge]

That won't work. If he calls it on thirds, and the other diver is near thirds, the high-SAC rate guy had better not have an OOA - there won't be enough.

[Superlyte27]

To answer the OP's question:

You put the larger tanks on the person who is most comfortable diving them. Period.
I could dive LP121's but the gain in cu' of gas would be lost in me being upside down on my back looking like an idiot.

Now that you're comfortable in the tank you like, figure out when to turn the dive. If you don't know how to do that, I can book a class with you for $300/day hehe.

[DA Aquamaster]

So, who should carry the larger set of doubles? The diver with the higher sac rate or the one with lower sac rate?

I would put the higher sac rate diver on larger tanks.

The argument against this is that it would put the team further into the cave and if higher sac rate diver were to loose all gas, there wouldn't be enough gas for both to come out.
I thought that when matching tanks(dissimilar tanks), it eliminates that problem, no?

What am I missing here?

Yes it does eliminate this as an issue.

As noted above, with proper gas matching, big tanks or small tanks does not matter, everyone on the dive will turn the dive when/if they arrive at the predetermined pressure equal to the "third" in the smallest set of tanks on the dive. That ensures everyone is diving the same size third and that any third will provide an adequate reserve for anyone else on the team.

Personally, I think thirds is pushing it too far in a low flow cave, so I'd scale it back another 100-200 psi from true "thirds" anyway.

[Sabado]

That won't work. If he calls it on thirds, and the other diver is near thirds, the high-SAC rate guy had better not have an OOA - there won't be enough.

Respectfully disagree...thirds is calculated based on all of the above...no matter who calls it, there will always be enough gas for both divers to make it out if either diver has an OOA situation.

The penetration distance is also the same no matter which diver has the larger tanks or smaller tanks. That's the whole purpose of calculating thirds based on dissimilar tank sizes. Penetration distance is the only thing sacrificed with higher sac rates...not safety.

[Pavão]

It should not matter because you should cylinder match to the gas used in the smaller tanks.

Mark Vlahos


Sent from my iPhone using Tapatalk

That's what I thought.

[bpcfire1]

RN is the man for this question