Are trim and buoyancy fundamentally related?

[HantsDiver]

Where does it say that in the OW class standards?

My students will remove and replace their BCDs in a swimming pool that is 11 feet deep. Most will do it in mid water. Sure, their fins will hit the bottom at times, but they don't crash to the bottom, and they don't go to the surface. It's not so hard. I will be glad to show you.

In the instructor manual. Confined water, dive 5 number 1.

It also states that weight belt removal should be done on the bottom in the instructor manual.

If they are touching the floor they are not in control of either they buoyancy, their position or their depth. So you are breaching standards no matter how you justify it. I'm sure it's not hard to teach badly lol

 

[MichaelMc]

I apologize for misspeaking a bit before, when I wrote ‘Things like mid water ditch and don in rough trim are good tests for advanced divers and leaders as a show of comfort..’ I more meant good exercises, or aspirational tests in the sense of learning beyond the minimum requirements.

My understanding from reading accident reports is that entanglement is one of the leading initiators. Being comfortable enough to exit from your gear, disentangle it, and re-don it it would very helpful. Practicing that in the calm pool waters seems a way to improve your ability to handle that or other problems that come up in a dive. Buddies are great, but I'd rather not depend on them being there or being capable of helping usefully.

Are we now arguing about when standards allow being not planted on the bottom? That seems separate from whether buoyancy and trim are intertwined, are (or are not..) great things to learn, and whether encouraging students to be able to solve problems without having to descend to the bottom is a good thing.

 

[gfaith]

I would think if you are entangled it would be tough to descend to the bottom before getting out of your Bcd/Bpw.

 

[Ayisha]

Why is it alarming?

The idea that you need to be able to do all skills in trim whilst neutrally buoyant before you can do any more courses is wrong in my opinion.

Wasn't it you, CharlieRogers, who said that you would post video of yourself in perfect trim and motionless while being neutral for the one minute you were asked to do so in another thread? Then after a wait and prodding, you finally posted something to the effect that it didn't work out and you were not as good as you thought you were. Kudos to you for admitting it. However, now you simply dismiss the idea that students may need to be proficient at skills while maintaining trim and depth before furthering their training? How does this make sense?

 

[Jack Hammer]

How does this make sense?

Internet, duh...

 

[Colliam7]

Not directly. But you should not lose control of buoyancy, body position or depth. If you are honestly telling me your students are doing this without a change in body position I'll hand back my tech 1 card and come and do an open water course with you.

The standards for the dive specify, as you noted in the first sentence, above, that the student should not 'lose control of buoyancy, body position or depth' (my formatting, added for emphasis). That is different from what you say in your second sentence, 'your students are doing this without a change in body position'. I can doff and don in mid-water and not 'lose control of buoyancy, body position or depth'. My OW students, before they can be certified, can doff-and don in mid water and not 'lose control of buoyancy, body position or depth'. But, my body position changes, as does theirs. The standards say nothing about change in body position, rather they emphasize control of body position.

The idea that you need to be able to do all skills in trim whilst neutrally buoyant before you can do any more courses is wrong in my opinion.

I think I understand your point, above, but want to clarify my interpretation, just to be sure. Certainly, 'the idea' is to be neutrally buoyant while performing these skills - i.e. you do not lose control of buoyancy. I don't know that maintaining horizontal trim is necessary - i.e. you don't lose control of body position, but body position may change. Now, I do think you should have control of body position and buoyancy, before sailing off into other courses - if I assess a student for AOW class, and they do not have control of their buoyancy, nor do they have control of their body position, I may well say that they need additional skill practice before I will allow them to take my AOW course. Having control of body position does not mean that they have achieved good (horizontal) trim. They may be a 45'er, in good control but in bad trim. THAT we can work on in AOW. But, if they have no control of their body position, they will have a hard time getting to the point of good trim.

It also states that weight belt removal should be done on the bottom in the instructor manual.

Yes, it does. 'Remove, replace, adjust and secure all or part of the weight system without losing control of buoyancy, body position and depth. • With weight belt and weight integrated BCD – on the bottom in water too deep in which to stand.' (My formatting added, again, for emphasis.) I regularly violate this 'standard' during Confined Water training, as I require students to do this mid-water / neutrally buoyant.

The comments about trim at deco stops resonate with me. I readily admit, I am generally not horizontal during the first part of an ascent from depth. I am moving most of the time, the early / deeper stops are pretty short, and I am preparing to move, so often I am a 45'er. Now, that changes at the shallower stops, and I almost always adopt good horizontal trim at the last / longest stop (which is almost always 20 ft for me). That is also where decoing divers tend to stack up, and maintaining a vertical or 45 degree angle position makes life difficult for others. In no current conditions, it isn't an issue, and we normally are off the line, horizontal, and spread in a circle around the line. In current, where we want to maintain contact with the line (and some folks have conveniently forgot to bring a jon line) horizontal trim is simply more efficient, and I prefer it. Oh, yes, I guess I should justify it by saying that horizontal trim allows my entire body to be at roughly the same depth.

Where our opinions might diverge just a bit is with regard to the value of certain skills, including the ability to maintain horizontal trim. I have doffed and donned my scuba rig mid-water in the ocean (fishing line entanglement), and I have doffed and donned my weight belt mid-water in the ocean (slipping weights, and no weight keepers). In each case, the situation was not an emergency, it was simply the simplest, quickest solution. I do not consider those skills to be a 'party trick' by any means. It is part of the skill precision that I believe all divers should seek as they develop. I don't consider maintaining good horizontal trim to be a 'party trick' by any means. It is part of the skill precision that I believe all divers should seek as they develop. And I no longer find it to be uncomfortable at all. It is efficient, environmentally friendly, and comfortable, at least for me. It is not a matter of safety, so I do not think accident and incident statistics have any relevance to this discussion. Other divers are free to maintain good control of a 45 degree body position and have fun doing it. (Possibly, the ones who probably aren't having quite as much fun are other divers in the area who may have to swim through the clouds of silt they kick up behind them, which they never see. )

 

[MXGratefulDiver]

I sometimes get a sense of vertigo but never any physical discomforts. However I've not yet encountered a practical reason to invert myself to such an extreme angle.

Photograpy ... in this picture I am neutrally buoyant. A good photographer can maintain neutral buoyancy in any position ... which is often required if you want to take a picture, since marine life isn't usually bound by such necessities as gravity ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

I don't know anyone who has ever had a course where they had to take their wing/bcd off in mid water. I can't see it being useful at all.

It's a required exercise in the NAUI Master Diver class (or was when I was teaching it a few years ago). I've had to do it once, when solo diving and getting an abandoned fishing line entangled around my tank valve. Wasn't that difficult ... but then, I'd practiced it a few times before having to do it for real ...

... Bob (Grateful Diver)

 

[Joneill]

Photograpy ... in this picture I am neutrally buoyant. A good photographer can maintain neutral buoyancy in any position ... which is often required if you want to take a picture, since marine life isn't usually bound by such necessities as gravity ...

View attachment 410884

... Bob (Grateful Diver)

Actually, marine life is still bound by gravity underwater - it just that the density of the medium provides different ways to manage it versus being in air topside

 

[MXGratefulDiver]

Actually, marine life is still bound by gravity underwater - it just that the density of the medium provides different ways to manage it versus being in air topside

Tell that to the warbonnet that's perched upside down or at some odd angle inside a boot sponge.

My point is that in the underwater environment you can't always count on getting a photo while hovering parallel to the bottom ... so underwater photography is as much about learning the skills to attain and hold a position in whatever orientation it takes to get the shot. This requires pretty good trim and buoyancy skills. With respect to the subject of this thread ... those are separate skills, but you need them both to some degree of proficiency to get the job done.

Back when I was teaching I often would have someone ask to take a photography class. Most went elsewhere after I explained to them that my photography class was going to put as much emphasis on their diving skills as it did their photography ... because you can't get good pictures without good diving skills ...

... Bob (Grateful Diver)