Rock Bottom

[jonnythan]

Uh, I do it, and there's no reason not to. I recently took DIRF, but I've been doing it since long before that.

It actually makes things far easier. When I'm doing a 90 foot dive, before we get in the water I can say to my buddy "let's head back at 1500 psi, but rock bottom is 1100 psi" and both of us know not to stay at 90 feet with less than 1100 psi, no matter what.

Like I said, it makes things easier. The 500 psi rule doesn't tell you a thing about when to actually head back to the shore or boat, but rock bottom does. There's no reason on earth not to.. it's easy, doesn't limit your gas too much, etc. Why wouldn't you?

 

[MXGratefulDiver]

Bob,

Didn't mean to suggest that anyone couldn't learn this, what I was offering was my response to Brad who stated that everyone does the 500psi thing. I'm not trying to split hairs or play games of semantics, but my comments were in response to the stated fact by someone else that "everyone else is doing teh 500psi thing"

In my view, the 500psi thing, that I agree is commonplace doesn't go far enough because it gives the end result, but doesn't give the student any meaningful information. What a student [ or diver for that matter] needs to know is how much gas do I need to get from the bottom, allowing time to square away the accident, allowing time for 30fpm ascent rates and allowing for appropriate stops..

Hope that clears up my comments and sorry if they were taken another way.

Regards

I understand what you're saying, and in fact, I think we were both saying the same thing ... your comments above square completely with my first reply in this thread.

My last comments were in response to the premise of what "everyone else" is doing ... simply because I'm part of "everyone else", as are the new divers I regularly work with.

Gas management is an area where I think the GUE approach really adds value to the industry as a whole ... because it highlights what is typically lacking in the approach to the topic taken by the more "traditional" Open Water instruction.

On the other hand, most serious divers I know eventually acquire this knowledge.

... Bob (Grateful Diver)

 

[roakey]

In my view, the 500psi thing, that I agree is commonplace doesn't go far enough because it gives the end result, but doesn't give the student any meaningful information.

My analogy is that it's akin to giving driving directions like "Turn right one mile BEFORE the big red barn."

Given directions such as this, you either guess right or guess wrong, but in either case, it's only a guess where you turn.

Roak

 

[ElectricZombie]

Because everyone else is doing the 500PSI routine.

Then everyone else needs to get their act together.

 

[boomx5]

and I also make sure my buddy practices rock bottom on every dive. Since everything in the DIR system is a team resource, it only makes sence for you and your buddy to both practice rock bottom.

 

[miketsp]

How many of you actually practice "rock bottom" when doing an open water, recreational dive?

I'm a rec diver, not DIR trained, but I've been around long enough to have done quite a few dives with deco obligation and seen enough equipment failures that I always calculate rock bottom for any dive beyond 20m to make sure I and my wife can both get up safely sharing what's left in either cylinder.

 

[jonnythan]

I'm a rec diver, not DIR trained ... I always calculate rock bottom for any dive beyond 20m to make sure I and my wife can both get up safely sharing what's left in either cylinder.

That's exactly how it should be, and there's no reason for it not to be.

 

[MXGratefulDiver]

Agreed ...

I just taught this stuff to my AOW student this week. Next week he gets to show me how well he understands it when I give him a site description for our deep dive and ask him to make a dive plan that includes gas consumption estimate and rock bottom calculation. If the class exercises were any indication, I've no doubt he'll do it just fine.

This student has about 30 dives, and told me he's already had an OOA experience. Must've been motivational, because he really chewed into the gas management session ...

... Bob (Grateful Diver)

 

[ScubaCrossing]

I have not taken any DIR classes to date. I do however calc out my rock bottom for dives deeper than 30 ft. I too was like you Brad until I became a member of this board and began reading the posts about SAC and rock bottom, I had no clue. No one ever explained to me the importance. Although it is in the PADI Deep Diver section of the Adventures in Diving work book, but it only calc's out in psi x min. not Cu ft3. Anyway I am saying I've seen parts during the DM course, but it was not taught in a way that tied everything together that opened your eyes to it. I do teach it in my advanced classes, and I introduce it in my OW classes, once introduced they ask questions so I can talk about it.

 

[MASS-Diver]

I learned it in my DIR-f class and use it all the time. I was/am pretty angry that it wasn't taught in my AOW or Deep class - just another reason I'll never waste my $ on another PADI class - they don't even teach you the most basic stuff you need not to die.