I'm sure it's a great idea but I strongly suspect it means more pool time per student which means higher prices which means fewer students which means less money for YSDAoC (your scuba diving agency of choice). Sounds like just the ticket.
"Correct Weighting" Identified as #1 Needed Improvement in SCUBA Diving
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I'm sure it's a great idea but I strongly suspect it means more pool time per student which means higher prices which means fewer students which means less money for YSDAoC (your scuba diving agency of choice). Sounds like just the ticket.
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If that is the case (and I will not comment one way or the other), I think it is foolish. While it is true that there are a large number of people who take open water to be able go on a dive trip just once in their life, I think it may make more sense to take more time to invest time and energy in students who are seriously interested in diving. Those are the ones who will take further classes, buy more gear, go on more dive trips and make the industry healthier. If they have a bad open water class, then they say forget it and move onto another sport.
Now mind you, these are just ideas. I haven't done any market research. But I think developing repeat customers may be more viable business wise than one time customers. I could be wrong however.
However, I am able to teach with smaller ratios (1 instructor to 4 students) neutral buoyancy in the same timeframe as a single instructor (often with another instructor helping out) would teach 8 students on their knees. I co-teach, so no revenue for the dive shop is missed. I don't see the issue, unless instructors want to squeeze every dive out of their time. I think there are many instructors who sincerely want to do the best job they can.
If that is the case (and I will not comment one way or the other), I think it is foolish. While it is true that there are a large number of people who take open water to be able go on a dive trip just once in their life, I think it may make more sense to take more time to invest time and energy in students who are seriously interested in diving. Those are the ones who will take further classes, buy more gear, go on more dive trips and make the industry healthier. If they have a bad open water class, then they say forget it and move onto another sport.
Now mind you, these are just ideas. I haven't done any market research. But I think developing repeat customers may be more viable business wise than one time customers. I could be wrong however.
However, I am able to teach with smaller ratios (1 instructor to 4 students) neutral buoyancy in the same timeframe as a single instructor (often with another instructor helping out) would teach 8 students on their knees. I co-teach, so no revenue for the dive shop is missed. I don't see the issue, unless instructors want to squeeze every dive out of their time. I think there are many instructors who sincerely want to do the best job they can.
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Back to the no BCD one more time:
Question (I really don't know the answer) :
You do a standard weight check without a BC (since with one, it's fully deflated then).
You're good, so you exhale and slowly (?) descend to 100'.
Can you put enough air in your lungs (and breathe that way with nearly full lungs) to
compensate for your 7 mil wetsuit compressing to 1/4 its thickness?
Question (I really don't know the answer) :
You do a standard weight check without a BC (since with one, it's fully deflated then).
You're good, so you exhale and slowly (?) descend to 100'.
Can you put enough air in your lungs (and breathe that way with nearly full lungs) to
compensate for your 7 mil wetsuit compressing to 1/4 its thickness?
I am not an instructor so my point is very much based on hearsay but a good number of instructors on this very board teach in mid water and actually find it easier and quicker overall.
AFAIK the initial buoyancy section might be longer but it is (at least) offset by the reduced time correcting the overweighting, buoyancy and trim issues.
With PADI, students are required in the pool sessions to do a weight check by holding a normal breath and dumping all the air from the BCD without kicking. With perfect weighting, the students will float at eye level and then sink when they exhale. If it is done with a full tank, they are often advised to add a few pounds to allow for the weight loss with air. Many people disagree with that, saying the method traps enough air in the gear to allow for that extra weight.
PADI requires a weight check with each OW dive. The understanding is that no system is perfect, and as the diver continues, they will continue to refine their weighting needs. By making these changes over four dives, you are also dealing with the reality of the situation--if you have a class of students, making each one as perfect as possible for the first dive will be such a time-consuming exercise that the instructor is unlikely to do it. It can work fine, though, if the instructor can say something like, "OK, you are a bit heavy right now. Before the next dive, try taking off 4 pounds."
Here is an example. I did OW dives in a fresh water lake for two divers whom I had not had in the pool. One of them had done his pool sessions in a 7mm wet suit instead of the usual 3mm suit because he wanted to have his weight perfect for the lake. He told me that because of that, he knew he needed 22 pounds. I looked at his slight frame and thought, "No way!" I also knew his pool instructor still did intruction on the knees, so I did not trust it. He was adamant, but I talked him into doing dive #1 with 18 pounds to start. I also showed him how to distribute the weight for trim, which had not been done in the pool. When we did the weight check, he sank while holding his breath. We did the dive and he was predictably clumsy. We started the next dive with 14 pounds, and he was still heavy. We did dive #3 with 12 pounds, and he was so much better in the water that he was elated. We did the final dive with 10 pounds, and he was great. IN that process, he learned how to check for his weighting, but more importantly he truly understood the benefit of being properly weighted and having the weight distributed for proper trim.
Unfortunately, the instructors who have the students kneel on the floor of the pool will also have them kneel on the bottom of the OW site whenever possible. They will thus still want the students overweighted. When they do, they are violating standards, but they need to do it in order to use their poor instructional technique.
As someone who has taught many students wearing a 7mm suit, I can say with confidence that the answer is no.
That is one of the drawbacks of diving a suit with that thickness (or more in some suits). You need enough weight to sink at the surface, but as you descend and the suit compresses, you do not need that much weight, and you will be diving overweighted to the degree that you have to use both the BCD and the lungs to compensate. Some people try to get their weighting as perfect as possible, and so to descend with a 7mm suit, they will invert and kick down. That will work, but I don't see the point in it. Put a little gas in the BCD, learn how to control it, and have a nice dive.
I like this question, so I will have a go at it.
I will say no, at 100 feet it would probably not be possible to put enough air in your lungs to neutralize the buoyancy shift in a 7mm wetsuit to 1/4 thickness.
Assume for simplicity starting neutral on the surface; as an example, me....
My 7 mm wetsuit (farmer john & jacket, so double thickness on the torso), when new, had a buoyancy of +20 lbs;
So compressed to 1/4 its buoyancy would be +5 lbs, so a buoyancy shift of -15 lbs.
Average adult male lung volume is 6 liters (which mine are) = 13.2 lbs buoyancy; but the original neutral buoyancy at the surface include residual lung volume, so really only about +10 lbs lung volume to get neutral with at most.
So with full lungs, I would still be at about 5 lbs negative on the inhale; and on an exhale, about 15 lbs negative.
So no.
Also, having done a 100 foot dive in this gear configuration, these calculations look about right, and I found that I do need the BC to get neutral. But, dropping 5 lbs would put me neutral on the inhale, and dropping 15 lbs would put me neutral on the exhale.
Depends on the gear though: If the question were, can a properly weighted diver in a 3mm shorty get neutral at 30 feet by breathing, the answer would be, yes.
I would like to point out that we're trying to reason with an unreasonable person. Fact, logic and reason will have no impact.
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