"Correct Weighting" Identified as #1 Needed Improvement in SCUBA Diving

[The Chairman]

I have no doubt that you can do that, I questioned your assertion that you can get OW students doing it at no extra cost.

It's not that hard at all. Everyone of my students do it three times before they get to go to OW. We have a 14 ft pool. Then the men have to be able to add an additional 6 pounds without using their BC and women have to be able to deal with another 4 pounds. All done with only breath control.

 

[boulderjohn]

Here's why it seems impossibly hard for many people.

After I had been doing neutral buoyancy instruction for a while, an instructor who was supposed to assist in a class took sick, and I replaced him. The primary instructor was an old school on-the-knees instructor, and he made it clear to me before the class that it would all be done his way, and I could just bite my lip and accept it. (Those were, indeed, his words.)

All instruction was done on the knees. All skills were performed on the knees except for the obvious ones (no mask swim, CESA). There was time built into the standards for "fun and practice." I am sure that was intended by PADI for free swimming, but the instructor had the students kneel on the bottom and pass torpedoes back and forth to each other. There was one required neutral buoyancy swim, and one lap of the deep end met the standard. It was tough to watch. The students had no buoyancy control whatsoever. They either went all the way to the surface, crawled on the bottom, or did both on that one lap of the pool. The instructor later laughed about it and said it was always like that. Those students finished their pool session with no buoyancy control whatsoever, and it was all done perfectly within standards.

When I was negotiating with PADI about writing the article, I described that class in detail, and the response was something along the lines of OMG! If an instructor were to do that today, it would be a gross violation of standards. There is plenty of neutral buoyancy swimming and more buoyancy instruction built into the class requirements.

So, if you went through an OW class such as I just described, then it is easy to understand that you would not believe that students can finish the pool sessions looking like experienced divers.

 

[dmaziuk]

... you may be able to more efficiently recruit your functional reserve capacity (better control / strength in respiratory muscles, increasing thoracic compliance, perhaps). Good freedivers may skew towards higher values because their physiology makes them more suited for it, but it's not really going to be a training effect.

The two I know of are pranayama yoga and whatever the diaphragm-stretching excercise in particular is called, and this: Lung Expander. I've no idea how much of an effect one could get from them, but I do know that training exists and freedivers use it.

 

[The Chairman]

@mselenaous was deeply skeptical that this was possible way back when. On one weekend visit, she had a class and asked me to join them as a DM. She had finished the pool and was in this crappy little lake (winds on the ocean were howling) that had a platform near the center. They knelt while I hovered around them. After the first dive, one of them asked how the hell I was doing that for so long? I said the bigger question was why he wasn't? It's easy, just do what I do! And... they did. Monkey see, monkey do. They were awesome and according to @mselenaous, they did pretty good when they got to finish their class. On the way home, she pointed out that I had taught them very little. That's what makes it so easy. As an instructor, you're their hero: their model. If you keep it neutral, so will they. No muss, no fuss... just a bunch of students emulating their instructor.

 

[wetb4igetinthewater]

just a bunch of students emulating their instructor.

I once helped out with a class where all the students were on their knees. The instructor had me demo underwater scuba kit removal and replacement. I did it midwater, and all the students did the same. They did so with some difficulty, but overall they got it. I was quite surprised.

 

[REVAN]

I'm still trying to come up with ideas for creating a balance of incentives to motivate divers to shed excess lead. Aside from diving no BC, or a simulated analog where they have a BC but just aren't allowed to use it during a training exercise, these are my brainstorm ideas (some are probably a little silly).

One idea is to have a modified BC that has a built in slow-leak. The more air that is maintained in the BC the more it leaks. If the diver has a lot of air in the BC during the dive, it becomes inefficient through leaking air overboard and cuts the dive short. Now there is an incentive to not overweight. Advantage, this would be fairly easy to make. Disadvantage, no one would want to use it except for training dives when they are forced to use it.

The second idea to have checkout dives where the students need to suit up and then hike 1/4 mile or more to the dive location. The hike is a motivation to minimize the amount of lead taken on the dive. Advantage, it's a cheap incentive to create. Disadvantage, doesn't work on boat dives, it's location specific, and is probably going to be a one time thing which limits usefulness for learning.

My third idea is to develop some kind of lift gauge that would show how much air is in a BC. I don't know how that would be built, but if it could be done, would it help the situation if diver's could see that they are swimming around with 10 or 12 pounds of air in their BC the entire dive? I would tend to think so. Advantage, provides a learning opportunity through obtaining more observable states of the diver's situation. Disadvantage, other than going back to idea number one and implementing a metered leak in the BC, I'm not sure how something like this would be made.

A fourth idea is to start using really small BCs for recreational diving and OW training. If a BC only had 8 pounds of lift, it could accomplish much of what could be done in theory by diving with no BC. It limits the amount of 'noise' that can be injected into the buoyancy equation to help streamline the learning process. Advantage, the BC would be small and streamline providing some possible advantages over bulkier systems and making it an attractive option to divers. (If it existed, I'd be interested in it as a product.) It would persuade instructors to start teaching midwater, because if they weight a student heavy enough to plant them firmly on the bottom, the student will not be able to float on the surface and they will complain about being too heavy (active feedback). Disadvantage, it is a new product that someone would need to make for it to happen. Limited capability to move into cold water or big air formats, unless it is a modular system.

What do you all think? Anything here ignite ideas for further discussion?

 

[TMHeimer]

A lot of technical stuff here. I do believe there is a lot of room for variance of lung size and how efficient one person could be using lungs alone for buoyancy as opposed to someone else. This is definitely true for wind players, particularly trumpet and to a lesser extent other brass. May be a factor for competitive swimmers as well (check out chest size on Olympians).

 

[The Chairman]

What do you all think?

​

 

[wetb4igetinthewater]

One idea is to have a modified BC that has a built in slow-leak. The more air that is maintained in the BC the more it leaks. If the diver has a lot of air in the BC during the dive, it becomes inefficient through leaking air overboard and cuts the dive short. Now there is an incentive to not overweight. Advantage, this would be fairly easy to make. Disadvantage, no one would want to use it except for training dives when they are forced to use it.

I don't see the value in this. If an instructor does his/her job, then students understand that they want to inflate their BCD minimally in order to dive, as drag is introduced by the more air that is in the BCD. Again, light enough so students can stay at 15' with no air in their BCD (and dry suit if applicable) and heavy enough to sink from the surface with an empty BCD. I don't see this as a difficult concept and I believe that instructors who teach midwater do this. Scuba diving is a lazy person's sport, meaning we move as slowly as possible to maximize our bottom time. If I remember correctly my university physics, drag is proportional to the speed squared.

The second idea to have checkout dives where the students need to suit up and then hike 1/4 mile or more to the dive location. The hike is a motivation to minimize the amount of lead taken on the dive. Advantage, it's a cheap incentive to create. Disadvantage, doesn't work on boat dives, it's location specific, and is probably going to be a one time thing which limits usefulness for learning.

Diving is supposed to be fun so that students continue diving. That doesn't sound like fun. I don't see any students agreeing to it. I know I wouldn't.

My third idea is to develop some kind of lift gauge that would show how much air is in a BC. I don't know how that would be built, but if it could be done, would it help the situation if diver's could see that they are swimming around with 10 or 12 pounds of air in their BC the entire dive? I would tend to think so. Advantage, provides a learning opportunity through obtaining more observable states of the diver's situation. Disadvantage, other than going back to idea number one and implementing a metered leak in the BC, I'm not sure how something like this would be made.

Same comment as for the first idea.

A fourth idea is to start using really small BCs for recreational diving and OW training. If a BC only had 8 pounds of lift, it could accomplish much of what could be done in theory by diving with no BC. It limits the amount of 'noise' that can be injected into the buoyancy equation to help streamline the learning process. Advantage, the BC would be small and streamline providing some possible advantages over bulkier systems and making it an attractive option to divers. (If it existed, I'd be interested in it as a product.) It would persuade instructors to start teaching midwater, because if they weight a student heavy enough to plant them firmly on the bottom, the student will not be able to float on the surface and they will complain about being too heavy (active feedback). Disadvantage, it is a new product that someone would need to make for it to happen. Limited capability to move into cold water or big air formats, unless it is a modular system.

@REVAN. I do respect your passion on this topic. The impression I get is that you are far more fit than the average person/diver. I just don't see how diving without a BCD is supposed to work at depth when one is in a wet suit. Maybe I'm not smart enough, but I'm not seeing it. Is the BCD used too much of a crutch? Sometimes it is, and that's a training issue that can be addressed with traditional/current training. I do know that I will emphasize to my students a bit more to stay off their LPI (I'm always looking to improve my teaching).

 

[Joneill]

I'm still trying to come up with ideas for creating a balance of incentives to motivate divers to shed excess lead. Aside from diving no BC, or a simulated analog where they have a BC but just aren't allowed to use it during a training exercise, these are my brainstorm ideas (some are probably a little silly).

One idea is to have a modified BC that has a built in slow-leak. The more air that is maintained in the BC the more it leaks. If the diver has a lot of air in the BC during the dive, it becomes inefficient through leaking air overboard and cuts the dive short. Now there is an incentive to not overweight. Advantage, this would be fairly easy to make. Disadvantage, no one would want to use it except for training dives when they are forced to use it.

The second idea to have checkout dives where the students need to suit up and then hike 1/4 mile or more to the dive location. The hike is a motivation to minimize the amount of lead taken on the dive. Advantage, it's a cheap incentive to create. Disadvantage, doesn't work on boat dives, it's location specific, and is probably going to be a one time thing which limits usefulness for learning.

My third idea is to develop some kind of lift gauge that would show how much air is in a BC. I don't know how that would be built, but if it could be done, would it help the situation if diver's could see that they are swimming around with 10 or 12 pounds of air in their BC the entire dive? I would tend to think so. Advantage, provides a learning opportunity through obtaining more observable states of the diver's situation. Disadvantage, other than going back to idea number one and implementing a metered leak in the BC, I'm not sure how something like this would be made.

A fourth idea is to start using really small BCs for recreational diving and OW training. If a BC only had 8 pounds of lift, it could accomplish much of what could be done in theory by diving with no BC. It limits the amount of 'noise' that can be injected into the buoyancy equation to help streamline the learning process. Advantage, the BC would be small and streamline providing some possible advantages over bulkier systems and making it an attractive option to divers. (If it existed, I'd be interested in it as a product.) It would persuade instructors to start teaching midwater, because if they weight a student heavy enough to plant them firmly on the bottom, the student will not be able to float on the surface and they will complain about being too heavy (active feedback). Disadvantage, it is a new product that someone would need to make for it to happen. Limited capability to move into cold water or big air formats, unless it is a modular system.

What do you all think? Anything here ignite ideas for further discussion?

Or you could just dive with a BC and determine your ideal weighting through performing iterative weight checks pre and post dive (with an empty BC) over several dives and then repeat the process if/when when you change gear configuration, environment or personal "mass"... you are overthinking something that is not a problem for those who care to improve their diving and maximize their buoyancy control skills - for those who don't, you are just wasting your time as they don't really care!