Big Heavy tanks!
- Thread starter jordaof
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Whoever slapped your hands was mistaken they're just different terms for the same thing.I got my hands slapped using the terms interchangeably ( SAC / RMV ) .. else why are they referencing different things? Ergo multi deco is wrong in how it uses the terms...
I could sit and argue the fact, but I will just say Ok to you and good day
Screenshot from multi deco shows them being used interchangeably
gordonscuba
Contributor
The SDI Solo Diver course has precise definitions for SAC and RMV as part of the chapter on gas planning. I don't know whether other agencies define them differently, but the SDI distinction pertains to whether one is completely relaxed at the surface, one is extrapolating data from previous dives of varying difficulty, or predicting the gas usage of a dive in the planning stage. In my view, such terminology distinctions are academic until they are used to improve someone's actual dives, e.g. used as part of a comprehensive system for proper pre-dive gas planning. The point is that divers should enter the water already understanding their gas consumption requirements for the dive. Even after appropriately adjusting for depth, converting all calculations to the surface, the same diver will have different results for actual volume consumed per minute for: (1) being completely relaxed at the surface, (2) an easy tropical wetsuit dive in zero current, (3) drysuit dive in cold water in a current carrying bulky equipment. What matters for one's safety is that one is able to predict the actual gas requirements of a real dive, before entering the water.
For deco diving, yes. For rec diving, I don't see how it adds any safety to know your sac rate. As I said, as soon as one person in the team hits return pressure, you head back home.
Min gas needs to be determined for knowing when to ascend/turn around. A magic number shouldn't be chosen. And for God's sake, no rule of thirds please for recreational diving.
Nobody has suggested to dive 3rds for OW NDL dives or use a magical number.
Have you never guided people? Depending on the dive site and max depth of 30m you turn at either 100 or 120 bar and swim back in shallower water. It's pretty much the standard and works, at least it worked for me with several thousand divers.
its a guesstimate with the hopes that no OOG emergencies exist.
It's not a magic number, Sherlock, it's half tank plus some extra, depending on the site. First grade math. The turning point is half the distance you swimm on a dive, you know. It works in actual diving and leaves plenty of spare gas for a direct ascent... the armchair divers might doubt it.
Not all dive sites are out and back. Just because you have thousands of dives on the same sort of sites doesn't mean your method is appropriate for the way a lot of divers actually dive.
If you have an OOG emergency at the turning point, do you have enough gas to get back? Or do you go straight to the surface? What is the boat traffic like there (if any)? How about current?
Given that we have no idea who you are, where you actually dive, we have idea how to answer these and other questions that are relevant to dive planning.
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