PADI OW and BPW

[wetb4igetinthewater]

Very true.

I went down the same path - 'blundered' into a Zeagle Ranger. It is actually a very nice unit, very well made, and Zeagle was a company that absolutely stood behind their products. But, that was then.

The challenge with the Ranger, and quite a large number of fabric (aka 'floaty'), weight-integrated BCDs is the placement of the weight, relative to the center of lift. When the diver is horizontal (e.g. underwater) that is not an issue. But, when the diver is vertical, it IS. The integrated weight pockets place the weight 'forward' of the frontal / coronal plane of the vertical (as in, at the surface) diver. The diver's center of lift is behind them, Lift and weight seek vertical alignment (i.e., the center of weight is direvctly below the center of lift), and THAT is what appears to push the diver's face down. It is a matter of physics. It is not a flaw with a back-inflate BCD, although I would venture to suggest that it is a (very real) flaw in the positioning of weight, particularly with a weight-integrated BCD. And, the more (over) weighted the diver, the worse the problem. For some reason, divers at the surface want to float with the water at chest level, rather than at neck level (where it should be). The more air that is added, in an attempt to push the diver 'up' abiove the water, the worse the problem becomes.

Nonetheless, take heart. Solutions are readily available.

1. Proper positioning of weight (e.g. weight pockets on the cam bands of many commercial weight-integrated BCDs represent a genuine attempt to address the design flaw (and that is what it really is) of weight-integrated BCDs. They moive weight fromin front of the coronal plane, to behind the coronal plane.

2. Use of a HP steel cylinder instead of an AL cylinder, which places more weight behind the coronal plane of the diver (yes, the cylinder IS part of a diver's weight system) is an option.

3. Use of a negatively buoyant BCD system, like a SS backplate, which also which places more weight behind the coronal plane of the diver, AND places it immediately adjacent to the diver's center of lift - the thorax - is an option.

I have said, repeatedly, in SB threads that, 'Gear doesn't make the diver, the diver makes the gear do what s/he wants it to do.' The preceding comments in no way change that position. But, when I dive my Aqualung Wave BCD (NOT weight-integrated, which I eschew with considerable enthusiam) I adjust my weight placement to maintain a reasonable balance between my center of lift, and center of weight.

Ahh, the Zeagle, aka the "Chamber Express". I jokingly call it that due to the tendency of local divers being so overweighted and if they were to dump weights while underwater, they're heading to the surface rather fast.

Completely agree on divers making the gear IF they know how to. Weight distribution is important just as proper weighting. I look forward to my blog series that I submitted to SDI (currently under review) on how I teach NB/T to share some of these ideas.

The problem is, not all divers straight out of open water know how to weight themselves properly and don't understand the repercussions of excessive weight and/or improper weight distribution.

 

[Colliam7]

The problem is, not all divers straight out of open water know how to weight themselves properly and don't understand the repercussions of excessive weight and/or improper weight distribution.

Yes, that is exactly right. It is not only total wegiht - distribution is equally important. And, I don't really hold the new diver altogether responsible. New divers are so overwhelmed by so many things - much of our well-intended preaching during OW training goes 'in one ear . . .'.

So, when a diver raises a good question here on SB, they have a chance to build on, and extend, their existing training.

 

[wetb4igetinthewater]

And, I don't really hold the new diver altogether responsible.

I hold the instructors completely responsible. There is waaaaaaaay too little emphasis on weighting. That's what motivated me to write that blog series (no idea when it will be out).

 

[Eric Sedletzky]

The problem is, not all divers straight out of open water know how to weight themselves properly and don't understand the repercussions of excessive weight and/or improper weight distribution.

That’s because the instructors don’t undo the overweighting scenario that they put them through during their open water course. Either the instructors don’t know any better because that’s how they learned and there was nobody to teach them any different, or they are trying to possibly sell them a PPB course in the future, or they know but are too embarrassed to tell them that they were purposely overweighted, or they’re just lazy and don’t care.
Proper weighting was something I learned from mentors and from old school veteran divers who dived a lot before BC’s were invented.
I never learned proper weighting from any instructor in any class I ever took.

 

[MichaelMc]

I would not discount the "The shop gear at hand (AL80s and BCs with forward-mounted integrated pockets) puts them that way" theory, plus overweighting.

 

[wetb4igetinthewater]

I never learned proper weighting from any instructor in any class I ever took.

Yeah that HAS to change. That is the rule, but there are exceptions. But the exceptions need to become the rule

 

[boulderjohn]

The challenge with the Ranger, and quite a large number of fabric (aka 'floaty'), weight-integrated BCDs is the placement of the weight, relative to the center of lift. When the diver is horizontal (e.g. underwater) that is not an issue. But, when the diver is vertical, it IS. The integrated weight pockets place the weight 'forward' of the frontal / coronal plane of the vertical (as in, at the surface) diver. The diver's center of lift is behind them, Lift and weight seek vertical alignment (i.e., the center of weight is direvctly below the center of lift), and THAT is what appears to push the diver's face down. It is a matter of physics. It is not a flaw with a back-inflate BCD, although I would venture to suggest that it is a (very real) flaw in the positioning of weight, particularly with a weight-integrated BCD. And, the more (over) weighted the diver, the worse the problem.

Yes, that is exactly right. It is not only total wegiht - distribution is equally important. And, I don't really hold the new diver altogether responsible. New divers are so overwhelmed by so many things - much of our well-intended preaching during OW training goes 'in one ear . . .'.

All of that is true.

My Zeagle was an original model, with only those front weight pockets and no trim pockets. As I slowly gained experience, I learned I was best off diving with the least amount of weight possible. When I took it on a liveaboard trip to Thailand, the boat only had weight sizes that would require me to be overweighted by a large percentage if I wanted to be balanced. A crew member solved the problem by putting a single weight on a weight belt and wrapping it high on the cylinder. It was a revelation! I felt ever so much in control of my diving. (I had never heard the term "trim" before.)

Soon after that I sold the Zeagle and bought a ScubaPro Nighthawk, which featured trim pockets at shoulder level. I found I would be in perfect trim if I had the same amount of weight in the high trim pockets as I had at waist level. Before long, I realized that having my weight trimmed out like that was more important than having the perfect amount of weight. I could comfortably dive overweighted if the available weights did not allow me to get the total correct. (After that the BP/W was introduced into my life.)

After that, Zeagle added trim pockets, but they did it nonsensically by putting them on the back of the BCD but at the same vertical level as the front pockets.

 

[boulderjohn]

Proper weighting is supposed to be a part of the OW course for all agencies in the WRSTC--it is in the standards. As one instructor who ignored those standards explained it to me (although not in these exact words), a student kneeling on the bottom of the pool or OW cannot be comfortably anchored when properly weighted.

A couple years after we published our article in the PADI professional journal on the advantages of teaching OW students while they are properly weighted, neutrally buoyant, and in horizontal trim, PADI rewrote the OW standards, and they included teaching trim. Students now see a video in which an instructor helps a student achieve horizontal trim by putting weight in shoulder BCD pockets. After they published those standards, they gave shops time to implement them.

During that interim, I certified two old friends. I did their pool work in Colorado, and then we vacationed together in Akumal, Mexico, where a local dive shop allowed me to complete their OW instruction on their boat. We had to rent jacket BCDs from them, and I used bungee cords to attach weights to the cam bands so my students would be in trim. (I had my BP/W.) The shop's instructors were intrigued. Why was I putting weights there? I explained the concept of trim to them, and I told them that according to the new standards, they were going to have to start doing that soon themselves.

About 1.5 years ago, I returned to Akumal as a base for cave diving. I was with children and grandchildren, and we snorkeled in the bay. On one such snorkeling experience, we passed over the top of an OW scuba class being taught by the shop I had used when I instructed my friends several years before. The students were kneeling on the bottom, comfortably anchored by overweighting, with no sign of trim weights anywhere.

 

[FishWatcher747]

Proper weighting is supposed to be a part of the OW course for all agencies in the WRSTC--it is in the standards. As one instructor who ignored those standards explained it to me (although not in these exact words), a student kneeling on the bottom of the pool or OW cannot be comfortably anchored when properly weighted.

A couple years after we published our article in the PADI professional journal on the advantages of teaching OW students while they are properly weighted, neutrally buoyant, and in horizontal trim, PADI rewrote the OW standards, and they included teaching trim. Students now see a video in which an instructor helps a student achieve horizontal trim by putting weight in shoulder BCD pockets. After they published those standards, they gave shops time to implement them.

During that interim, I certified two old friends. I did their pool work in Colorado, and then we vacationed together in Akumal, Mexico, where a local dive shop allowed me to complete their OW instruction on their boat. We had to rent jacket BCDs from them, and I used bungee cords to attach weights to the cam bands so my students would be in trim. (I had my BP/W.) The shop's instructors were intrigued. Why was I putting weights there? I explained the concept of trim to them, and I told them that according to the new standards, they were going to have to start doing that soon themselves.

About 1.5 years ago, I returned to Akumal as a base for cave diving. I was with children and grandchildren, and we snorkeled in the bay. On one such snorkeling experience, we passed over the top of an OW scuba class being taught by the shop I had used when I instructed my friends several years before. The students were kneeling on the bottom, comfortably anchored by overweighting, with no sign of trim weights anywhere.

Boulderjohn, you are making the same reasoning (although more eloquently) that I was making in a recent thread. As a new diver I was having a discussion with Collium7 about being unable to distribute my weights in a very popular mid priced jacket BCD to avoid being foot heavy. This jacket, Aqualung Pro HD has integrated weight pockets and trim pockets on the one cam band.

My options going forward were to put an ankle weight on the tank neck, or buy a second tank cam band and put trim pockets high up on the tank. I actually ordered the the extra cam band but by that time I said screw it and ordered a stainless steel backplate, harness and 32 # wing. I will try the new wing next week.

My suggestion is we teach a standardized "trim test" just as we teach a standardized "weight check" Get horizontal in water with arms in front clasping wrists together but arms not straight out. Thighs straight back and lower legs up at 45 degrees. Then do you stay neutrally trimmed? Head heavy? Foot heavy?

Then redistribute weights until one is neutral. If this is being taught it wasn't taught to me in PADI OW, AOW, Rescue.

 

[tursiops]

If this is being taught it wasn't taught to me in PADI OW, AOW, Rescue.

Did you perchance *ask* about it in those classes? I know, you can't ask about something you don't even know about....but even so, did you ask?