Not Enough Weight?

[elmo]

Sorry guys I meant VERTICAL. Straight up/down

That may be your issue! And I definitely agree with the suggestion to get a buddy to video you.
Many divers will keep finning even when they don't realize. If you're horizontal, you'll struggle to stay in one place. If you're "head up" or vertical, you'll ascend. Many divers (and instructors) offset this by over-weighting you, further encouraging you to fin subconsciously to stop you from sinking. You'll breath through your gas quicky because you're constantly working too.
If you feel yourself ascending. Stop. Think. Breath normally. Then work out if you are actually positive or negatively buoyant and adjust with your bc.
Don't be afraid to do shallow "boring" dives to practise. Ask your buddy to video, and seek the opinion of divers that look really controlled and relaxed in the water.

 

[admikar]

Do a weight check on the surface, eliminate weight until you can float at eye level with an empty BCD holding a "normal" breath. At that point, when you then exhale you will sink, and become more negative as you continue to descend (and you descent rate will increase). You will then need to add very small amounts of air to your BCD to slow and finally arrest your descent.

As above, but with a note that you should do this with your tank near empty.

That may be your issue! And I definitely agree with the suggestion to get a buddy to video you.
Many divers will keep finning even when they don't realize. If you're horizontal, you'll struggle to stay in one place. If you're "head up" or vertical, you'll ascend. Many divers (and instructors) offset this by over-weighting you, further encouraging you to fin subconsciously to stop you from sinking. You'll breath through your gas quicky because you're constantly working too.
If you feel yourself ascending. Stop. Think. Breath normally. Then work out if you are actually positive or negatively buoyant and adjust with your bc.
Don't be afraid to do shallow "boring" dives to practise. Ask your buddy to video, and seek the opinion of divers that look really controlled and relaxed in the water.

Bolded part.

 

[Dish]

@ouichef - I'm not an instructor, so take this with a grain of salt, but what we have in common is being 6'6" tall. We have big lungs. It used to take two plates to get an entire x-ray picture of my lungs. I suspect you're the same. I can stop a descent by taking a full breath and and can also crash into the bottom, at depth and with 3mm suit, with a full exhale. We need to be more sensitive to how deep we breathe. I would continue to seek nominal weighting, but breath control can really do wonders for you. Talk with your instructor about this.

 

[EricTheDood]

Breathings no problem, used to controlling it from years of Judo and BJJ.

I'd bet money that the problem's in your breathing. The laws of physics don't change from individual to individual.

Martial arts training makes you good at martial arts. It doesn't carry over into diving, except for maybe some added flexibility.

 

[Dish]

I'd bet money that the problem's in your breathing. The laws of physics don't change from individual to individual.

The laws don't change, but individual physiology is a variable; which is my point. If diving balanced, your lungs are your natural BCD. Larger lungs are like higher lift capacity wings, which you are constantly inflating and deflating with every breath. @ouichef and I are both 99.8 height percentile guys. That needs to be a consideration when diagnosing trim and balance issues.

 

[EricTheDood]

The laws don't change, but individual physiology is a variable; which is my point. If diving balanced, your lungs are your natural BCD. Larger lungs are like higher lift capacity wings, which you are constantly inflating and deflating with every breath. @ouichef and I are both 99.8 height percentile guys. That needs to be a consideration when diagnosing trim and balance issues.

Yes, physiology affects the parameters, but it doesn't change the technique.

There's a delay between inhale to updwards movement and exhale to downwards movement. It takes a few dives to get used to it, which could be the OP's issue.

 

[theodorthiele]

I agree that the breathing may have a lot to do with it, I find that new divers are always told in the books / by instructors to breathe deeply and slowly. This is done to make people who are new to diving think about their breathing, and avoiding super fast breathing, which is likely to come as a result of being scared / excited. The issue, however, is that people tend to breathe too deeply, causing buoyancy issues. Especially when you have larger lungs (which tall people do), filling up your lungs and then emptying them all the way will make you go up and down constantly. You need to breathe slowly but not heavily, that way you can actually breathe and keep constantly neutral, rather than changing between being positive and negative. I think of it kind of like if I was breathing through a straw, and how I'd breathe through one naturally (not trying to suck as hard as possible).

 

[TMHeimer]

Yes, physiology affects the parameters, but it doesn't change the technique.

There's a delay between inhale to updwards movement and exhale to downwards movement. It takes a few dives to get used to it, which could be the OP's issue.

Yes, I think I mentioned that. The delay can at times be longer than you'd think.

 

[boulderjohn]

I agree that the breathing may have a lot to do with it, I find that new divers are always told in the books / by instructors to breathe deeply and slowly. This is done to make people who are new to diving think about their breathing, and avoiding super fast breathing, which is likely to come as a result of being scared / excited. The issue, however, is that people tend to breathe too deeply, causing buoyancy issues.

Yes, people do tend to breathe too deeply, and this does cause buoyancy issues. When I teach an OW class, in the very first session, I have the student lying on the floor of the shallow end of the pol facing me, neutrally buoyancy so that their breathing will make them rise and sink. I breathe in and out, using my fingers to show when I am inhaling, pausing, exhaling, pausing, inhaling, etc. I have them breathe with me. The few minutes it takes to do this does wonders for them for the rest of the class and probably the rest of their diving lives.

Yes, I think I mentioned that. The delay can at times be longer than you'd think.

The delay is caused primarily by the overbreathing mentioned above. If you have overdone it and are starting to ascend with some velocity, your exhale actually starts to work immediately, but your momentum carries you for a bit. That is why it seems like a delay. Once you get into decompression diving and are trying to hold a stop at say 20 feet without going up past 10 and down past 21, you won't notice much of a delay because your breathing is so much more controlled.