Can someone please explain?

[RN]

Single 100 - 1/3 is 33.3 penetration. If you breathe 3cf/min you will only penetrate for 11 mins. At 50 fpm that's 550 ft penetration.

Double 100s - 1/6 is 33.3 penetration. If you breathe 3cf/min you will only penetrate for 11 mins. At 50 fpm that's 550 ft penetration.

That's what the agencies are trying to limit. However, if I get what you're saying, I agree. It should be based on how much gas is left for egress, not on how much gas is used for penetration.

[Tegg]

However, if I get what you're saying, I agree. It should be based on how much gas is left for egress, not on how much gas is used for penetration.

Mind explaining further.

[CaveMD]

I never understood it, someone with a good sac rate can make it a long ways on 1/6's of 108/121's filled to hydro. Would have made more sense to make a linear penetration limit along with 1/6's of both single or double tanks.

[RETIRED 11]

In my humble opinion... egress is the goal.... Success is getting out after an enjoyable dive...

[Tegg]

I never understood it, someone with a good sac rate can make it a long ways on 1/6's of 108/121's filled to hydro. Would have made more sense to make a linear penetration limit along with 1/6's of both single or double tanks.

The depth limitation helps with that (no deco)... and honestly, I have not seen very many intro divers with a great SAC rate.

[RETIRED 11]

Cave diving is like sex... Penetration is not the issue.... your actions on the way in and on the way out are far more important,,

[RETIRED 11]

Why differentiate?? 1/3's or 1/6's of the gas you are carrying.

[CaveMD]

The depth limitation helps with that (no deco)... and honestly, I have not seen very many intro divers with a great SAC rate.

That's true, but their are some places like mexico or telford where there is a lot of main line at shallow depths. IIRC at telford you can get to the expressway >p2400' without hitting deco or leaving the main line.

edit: I forgot about the sink hole jumps at the beginning of telford...I don't know if Intro can do that or not since there is a main line running into each sink with access to open water but they aren't actually connected?

[Sludge]

Here's an answer you may like better: it only allows you to go half as far as you can go at the apprentice level.

[RETIRED 11]

Here's an answer you may like better: it only allows you to go half as far as you can go at the apprentice level.

Not all training agencies have "Apprentice level" (Playing devils advocate here) really, if you use 1/3 of your gas in for one situation, why is it inadequate for another?