Last night, we had the pool session for our NAUI Master Scuba Diver class, and one of the fun diversions was lift bag use. I'm no stranger to lift bags, as we covered them in the Advanced class, and I've been using one quite a bit since then. (Hey, what can I say? It's fun to play with toys.)
Anyway, I didn't think I was having a problem with the skill, but the divemaster assisting our instructor apparently disagreed. He signaled me to dump air and get on the bottom of the pool, and then when my buddy and I surfaced, he chided me for floating and told me that I should *always* be heavy and kneeling on the bottom when using a lift bag. I mentioned that most of my experience using lift bags had been on very silty bottoms, and if I knelt on the bottom, wouldn't that be a bad idea? He said it doesn't matter what the bottom is; you should always be negative and on the bottom when using a lift bag.
Okay, then. I know that the Internet has not been certified as an active NAUI, PADI, or other instructor (I think it just can't handle the swimming trials), but I would like to hear comments on proper lift bag technique. Was the DM correct, or is it perfectly reasonable (or even recommended) to maintain neutral buoyancy and horizontal trim while working with a lift bag? If you *must* be negative and kneeling on the bottom, what in tarnation are you supposed to do when you want to lift a lost anchor from a poor (but not defenseless) coral reef? If you kneel in silt and completely destroy the visibility, won't that make the lift much less safe?
Obviously, if you need to dig a bit to free the thing or get rope around it, you've got no choice but to go with it, but if you're lifting an outboard off a silt bottom, wouldn't it be better *not* to silt everything to mud? Also, wouldn't it be more productive to be able to give a quick fin kick to maintain vertical control at the beginning of the lift, just in case you slightly over-lift and need a moment to dump a bit of air to prevent a runaway? I know I can produce a nice chunk of thrust from a kick, but not if I'm kneeling on the bottom. I'm weighted to be neutral with an empty BC and tank at 15', so it's not like I could be as negatively buoyant as the downward thrust from a fin kick.
If you're that negative when you get the lift+bag to neutral, won't that make it more complicated, since you'll have to get yourself back to neutral to fin away with the lift, too? And how about the technique of using a rope with loops every 10 feet or so and using two lift bags in sequence to walk the lift up the water column? You obviously can't do mid-water lifts while kneeling on the bottom, right?
Well, there you have it. Is my lift bag technique completely wrongheaded and dangerous? Should I heed or ignore the DM's advice, or is there some truth to both sides, perhaps? Is it better to get negative and kneel when possible, but to know how to do lifting skills while neutrally buoyant for those times when you ought not be on the bottom, and if so, how do you decide which technique is appropriate?
I'm skeptical of the DM's advice, but I'm openminded enough to consider that either of us may be right or wrong, and in varying degrees. I figured this ought to be a good place to ask about it diplomatically. (I wasn't about to go up to the instructor in front of the DM and ask. Would've been rude. Still, I want to know more so I can discuss it with the instructor next class.)
Anyway, I didn't think I was having a problem with the skill, but the divemaster assisting our instructor apparently disagreed. He signaled me to dump air and get on the bottom of the pool, and then when my buddy and I surfaced, he chided me for floating and told me that I should *always* be heavy and kneeling on the bottom when using a lift bag. I mentioned that most of my experience using lift bags had been on very silty bottoms, and if I knelt on the bottom, wouldn't that be a bad idea? He said it doesn't matter what the bottom is; you should always be negative and on the bottom when using a lift bag.
Okay, then. I know that the Internet has not been certified as an active NAUI, PADI, or other instructor (I think it just can't handle the swimming trials), but I would like to hear comments on proper lift bag technique. Was the DM correct, or is it perfectly reasonable (or even recommended) to maintain neutral buoyancy and horizontal trim while working with a lift bag? If you *must* be negative and kneeling on the bottom, what in tarnation are you supposed to do when you want to lift a lost anchor from a poor (but not defenseless) coral reef? If you kneel in silt and completely destroy the visibility, won't that make the lift much less safe?
Obviously, if you need to dig a bit to free the thing or get rope around it, you've got no choice but to go with it, but if you're lifting an outboard off a silt bottom, wouldn't it be better *not* to silt everything to mud? Also, wouldn't it be more productive to be able to give a quick fin kick to maintain vertical control at the beginning of the lift, just in case you slightly over-lift and need a moment to dump a bit of air to prevent a runaway? I know I can produce a nice chunk of thrust from a kick, but not if I'm kneeling on the bottom. I'm weighted to be neutral with an empty BC and tank at 15', so it's not like I could be as negatively buoyant as the downward thrust from a fin kick.
If you're that negative when you get the lift+bag to neutral, won't that make it more complicated, since you'll have to get yourself back to neutral to fin away with the lift, too? And how about the technique of using a rope with loops every 10 feet or so and using two lift bags in sequence to walk the lift up the water column? You obviously can't do mid-water lifts while kneeling on the bottom, right?
Well, there you have it. Is my lift bag technique completely wrongheaded and dangerous? Should I heed or ignore the DM's advice, or is there some truth to both sides, perhaps? Is it better to get negative and kneel when possible, but to know how to do lifting skills while neutrally buoyant for those times when you ought not be on the bottom, and if so, how do you decide which technique is appropriate?
I'm skeptical of the DM's advice, but I'm openminded enough to consider that either of us may be right or wrong, and in varying degrees. I figured this ought to be a good place to ask about it diplomatically. (I wasn't about to go up to the instructor in front of the DM and ask. Would've been rude. Still, I want to know more so I can discuss it with the instructor next class.)
