Geek,
The fact that youre willing to experiment and practice this will put you way ahead of the typical learning curve, congratulations!
First off, think of fin pivots as a skill done with training wheels. If you can do fin pivots, your trim in the water is all wrong: youre heads up/feet down. This both makes it difficult to maintain neutral buoyancy when you stop and start swimming and causes you to consume more gas.
The reason why this is the case is if youre trimmed head up/feet down (typical trim for a recreational diver), the moment you start swimming some of your thrust is going down, so you start up. In order to swim neutral you have to let some gas out of your BC to become heavy to counteract the downward thrust of your fins. This means that some of your energy is spend swimming up all the time, increasing your gas consumption. Now when you stop swimming youre negative because youve let gas out of your BC, so now you have to add some back in to get neutral.
The constant start swimming, dump gas, stop swimming and add gas is quite common among recreational divers.
You can adjust to some extent by altering your body position, but then youre just substituting hydrodynamic forces and drag for the wrong swimming vector. Your gas consumption loses in either case.
So, the reason I say fin pivots is a skill done with training wheels is that if youre correctly trimmed, youre horizontal. If youre horizontal, you cant do a pivot, you rise horizontally, your entire body coming off the bottom as a unit.
There are a number of ways to accomplish this, the quickest fix is to take some of your weight and move it high on the cylinder. You want to move some significant weight up there, not just using the trim pockets that some BCs sport. To take some numbers out of the air, if you wear 16 pounds of lead, move 8 to the shoulder of the cylinder. Sometimes you can accomplish this by putting the weight on the top cam strap that holds the cylinder onto the BC. Now jump in and play around a bit. If need be add or subtract from your original guess until without swimming or moving, youre horizontal. The weight required may vary as your cylinder empties, so the weight you end up with will be a compromise.
Now you can start playing with your breath control. Go to the bank and buy a roll of pennies, open it up and throw it in the pool. Now swim around and after positioning yourself over a penny, just use your breath to drop down and pick it up without touching the bottom. As you get better, reach out for it less and less so your body ends up very close to the bottom, but not touching it. Try this in the shallow end of the pool too. The shallower, the more difficult the exercise.
As funky__monks mentions theres a LOT of hysteresis when youre in the water. Another part of learning trim and breath control is to allow the dive to come to you. Never rush any activity, but instead anticipate your needs. Itll take some time for you to start dropping after an exhale and even more time to arrest the descent and start back up on the inhale. Standby, heres the Zen-sounding part! The whole trick is to be ahead of your diving, to anticipate what you need to do. You heard that you should move slowly in OW class, but those are probably just words to you at the moment, you really have to learn to take it easy and learn patience. Ive been on many a dive where Ive had divers zipping around me like a puppy dog on a leash, and they burned up all their gas in no time and saw less than I did.
So, what you need to work on:
Proper trim
Anticipate your next move
Be patient with the hysteresis
Look around and enjoy whats around while youre moving slowly and deliberately.
Roak
