From pivot to perfect.

[lowwall]

IMHO, the fin pivot is a stupid, moronic, evil, counterproductive, waste of time. It was the only thing I had trouble with in my OW class (which was 20 years ago when PADI did require them). Actually I never managed a textbook fin pivot, but my instructor let me slide.

The problem? When I inhaled, my whole body rose up. And when I exhaled, my whole body went down.

 

[Coztick]

PADI does not require fin pivots.

IMHO, the fin pivot is a stupid, moronic, evil, counterproductive, waste of time. It was the only thing I had trouble with in my OW class (which was 20 years ago when PADI did require them). Actually I never managed a textbook fin pivot, but my instructor let me slide.

The problem? When I inhaled, my whole body rose up. And when I exhaled, my whole body went down.

Now imagine being fin heavy like the majority. The attempt demonstrated your excellent weighting! Sounds like a pass in my method.
Try a dive with ankle weights. Many must finish OW like that as bad trim is a common sight.

 

[Coztick]

Actually, I started working on getting my weight right, right after completing OW. Here's a link to a post that summarized what I did. So, I got the weight right before I took PADI's PPB. In that class we worked exclusively on trim which I had not worked on before. It was more like spending $500+ to get the weight and trim perfected after OW (I took AOW and then PPB). In PPB (Peak Performance Buoyancy) my instructor had me remain absolutely still. To my surprise I went completely head down like a trumpet fish. The CD of the dive shop had a body type similar to mine and decided I needed 2+2 lbs in the upper trim pockets of my ScubaPro Nighthawk BCD. Once those weights were moved to the waist pockets my trim was perfected and I added 15 minutes to a typical dive I was doing at that time. From that point on, getting the neutral buoyancy perfected was much easier. For me, it was around 70 dives where I felt really comfortable and to the point where I felt I had mastered neutral buoyancy.

Nice!
I was opposite. In a Ranger BC, I was slightly leg heavy. Easy enough to manage but far from perfect.
Problem being I didn't know any better until my sm course! That was 25 dives in for me.

Cheers!

 

[TMHeimer]

I agree there are better ways to become neutrally buoyant (and horizontal) than the fin pivot. But by now you all know that I will say learning the fin pivot (and practicing it after OW course-- a fair bit) doesn't seem to have hurt me any--not that I can tell. Ie., I don't THINK it caused me to get into any bad habits.
I can see it's use to just illustrate breathing, as John mentioned.

I'm trying to figure this--
If you are already neutrally buoyant but lying on the bottom (I believe you can be in this situation since you could be NB anywhere in the water column and simply empty lungs to land on the bottom),
you may not be feet heavy if you do the fin pivot. When you inhale your torso will rise because that's where your lungs are. Your fin tips will thus remain on the bottom.
When supervising students in the ocean on their knees, I used a version of an elevated fin pivot (fins not touching bottom) to get a good view of the group.

 

[lowwall]

When you inhale your torso will rise because that's where your lungs are. Your fin tips will thus remain on the bottom.

Your center of bouyancy doesn't really shift fore and aft as you breathe. As you inhale the chest cavity expands down towards the abdomen as well as expanding the chest wall.

Which means if you are in trim, your whole body will rise when you inhale regardless of your attitude. If you are horizontal, you will remain that way. Of course with muscular control and even small movements you can change your attitude.

 

[wetb4igetinthewater]

Well, I think in that other thread I made my viewpoint on fin pivots fairly clear. Again, it is about the diver being negatively buoyand and foot heavy. That's the problem. If a student is properly weighted, they are trimmed out, rise and fall with the breath.

The question I have is, why introduce this unnecessary step/exercise?

I realize the lack of skill and knowledge of many instructors is a problem. But that's a remedial training issue for those instructors.

In my area, pool time is very expensive. $160/hour. I found I saved a lot of time by teaching NB/T right from the beginning and had time for fun "games", such as a race holding a golf ball on a spoon (required slow and smooth finning, my students loved it). There are different buoyancy games that can be played, such as building "houses" with weights white neutrally buoyant and trimmed (can't touch the bottom, inhale as picking up a weight, exhale as placing it). There has been a shop that use Hood Canal for their confined water sessions (um, okay). But then that's cold water, thick wet suits or dry suits. I don't see the technique of holding weights over one's head to be very effective for when confined water is cold (per multiple agencies, confined water has to be pool like in terms of clarity, calmness, and depth. But not temperature).

 

[decompression]

Can't "moving through the water" itself affect trim? Wouldn't perfect trim/weighting be most obvious to the student while hanging motionless?
Even 2lbs moved 1 foot will affect trim if motionless. This would be unnoticed while swimming.
"The Fin pivot introduces 2 negatives,"
YES! Touching the bottom of a pool once and FIN HEAVY.
At that moment a little weight transfer upward, the fins come up and good trim is achieved. Now while they focus on breathing they can FEEL perfect trim.
Alternatively, the instructor could make the adjustment with soft weights on the divers upper back. 3 posts later, Jim says just the arms forward is enough.
Taking OW, I found the pivot easy and effective to learn the effect breathing has on buoyancy. I just wish they would have corrected my weighting at that moment.
I was just suggesting that perfect trim could be incorporated the moment neutral buoyancy is achieved very easily to give a student more control and confidence.
I was a little fin heavy and had to scull with fins to hover but got by fine for my first 25 dives assuming that was normal.
Thinking back, it probably had something to do with the fatigue I felt on my first few trips that pushed me to try sm, so all's well.
I'm no instructor, never will be. I certainly respect your input. "From the mouths of babies.." they say. Just thought it might be useful. It made more sense than the floating limbo bar in another thread.

Cheers!

i love the fact that you are really thinking about this.....many long time instructors don’t even bother.
For benefits sooner (as you noted), weighting must be done very early. Definitely prior to fin pivots.

in my classes, dry work begins with the trim position and dry propulsion training, breathing has been and is continually discussed. Once in water, weighting begins with no gear and breathing (in trim). Then breathing from longhose with no gear, learning how body position/weights affect trim. Ascend/descend in trim, no gear, off of longhose. This takes about an hour and lays the foundation for all other skills to be performed neutral, in trim and having fun!

remember the difference between trim and propulsion, they can affect each other. If your out of trim and you propel you’ll certainly go that way.......depending on lung volume.

 

[TMHeimer]

Your center of bouyancy doesn't really shift fore and aft as you breathe. As you inhale the chest cavity expands down towards the abdomen as well as expanding the chest wall.

Which means if you are in trim, your whole body will rise when you inhale regardless of your attitude. If you are horizontal, you will remain that way. Of course with muscular control and even small movements you can change your attitude.

Well, your physiology knowledge may exceed mine, but I think the lungs (and even abdomen to a point) are closer to your head than your feet. Agree that muscular control can change things. Either way, I've never had problems either swimming/hovering horizontally or doing a fin pivot. I wouldn't label it moronic and the other terms you use, but would agree there are probably better ways to introduce neutral diving and hovering.

I get on my old band wagon saying that having been taught the fin pivot shouldn't hurt your diving--IF you had some comfortability in water before the OW course AND you dive regularly after taking it.
I understand there are many who disagree.

 

[lowwall]

Well, your physiology knowledge may exceed mine, but I think the lungs (and even abdomen to a point) are closer to your head than your feet.

True and if you are naked and unconscious, your legs will dangle below you. But if we are talking about people already in trim in their gear, exhaling and inhaling won't change their attitude, it will just move the whole body up and down.

I suspect that in practice most people were actually trimmed head up/feet down in OW classes 20 years ago which is why fin pivots worked most of the time. Overweighting was common and the weight belt sits below (aft) of the divers's center of buoyancy, especially with a standard BCD.

Agree that muscular control can change things. Either way, I've never had problems either swimming/hovering horizontally or doing a fin pivot. I wouldn't label it moronic and the other terms you use, but would agree there are probably better ways to introduce neutral diving and hovering.

I'm sticking with moronic and counterproductive. Time is limited in class. It should not be wasted on something that forces a diver to be badly trimmed. Replace the pivot with the body rising and falling with inhalation and exhalation midwater and you've accomplished what the fin pivot is supposed to do in demonstrating buoyancy control. As a bonus, trim problems will be immediately evident and thus can be corrected before they becomes ingrained.

 

[Raphus]

As i said before, i am a DM in training.
I am always good weighted and i am fokused to have good trim.

Then the pool skill training started.
I use a 5mm without weigth in a pool.
There is no way i can do a fin pivot..
My trim becomes horizontal and my fins leave the bottom, when my upper body starts to ascent. Thats the way it should be right?
No not for the fin pivot..
So i have to add 2 extra kg to weigth myself down to the bottom, so i can do the fin pivot. That just doesnt make any sense to me.