Air consumption and other ramblings

[bradshsi]

I don't claim to be either "very" or "experienced", but I can roughly predict my SAC for different dives. I'll monitor the SPG to see if I'm about where I should be. If I am too high or low I'll start looking for problems with my gear.

I still use PADI tables to do a check against the dive plan in my computer. With care you can use those tables even to estimate multi level dives.

I also use Rock Bottom for air planning. Sadly I find most DMs and insta buddies don't seem to either know about it and/or care. To be honest it beats me how they can do gas planning without it. Maybe its some special magic trick. ?

 

[ianr33]

I was reading a thread on SAC rate, and it made me wonder. Can very expreienced divers, knowing their "typical" SAC rate closely estimate their upcoming air cumsumption rate on a dive by adjusting the SAC rate for depth,

Did a dive a few years ago in Cayman. 200 feet for 20 minutes.

Afterwards buddy said he noticed at the start of the dive his spg was tangled up in a stage somehow and he could not read it. He was not in the least bit bothered as he KNEW he had plenty of gas

While I dont exactly recommend diving without an spg, with experience you get a real good feel for what your pressure is without even looking.

Deco programs such as V-planner tell you how much gas you need on any particular dive for a given SAC rate.

 

[BKP]

SPG's are over rated...you should be able to get to a point where you can guestimate within a few hundred psi based on a good track record of previous dives under various conditions...

I typically can guestimate, and said so in my original post...

However, a wall dive, or any dive with current and/or changing variables, I wouldn't simply leave it up to intuition... gauges have their moments...