Not needing air for buoyancy control ?

[RobPNW]

In theory, during a warm water dive with something like a rash guard, I typically dump everything from my wing to get to depth, add a couple puffs of air at depth to level off, bleed some off about 50-75% through the dive and end up empty at the safety stop. Maybe touch the inflator 4-5 times total during that kind of dive. Using the inflator less is good from the standpoint of using breath control for buoyancy, but don't let yourself start breathing too shallow or too deep to do so when a tiny adjustment once in a while does the trick.

 

[dmaziuk]

Is this a good or bad thing ?

It depends. At the start of the dive you should be "too heavy" by the weight of the gas in your tank. Depending on the tank and the depth and the size of your lings, you could go without adding any air in the beginning to compensate.

Personally I wouldn't care to do that at 120' with an Al80: I'd have to keep my lungs full all the time and likely fin up too, to stay at depth. And I do have big lungs.

 

[Chavodel8en]

Im assuming you had your BC inflated on the surface before your dive, and then defated it to descend. From your description, this is not very clear-- it sounds like maybe you never adjusted your BC at all before your descent, just afterwards.

I think this is why people are inquiring as to whether you were too heavily weighted -- because they're assuming you descended without dumping air?

In any case, not having to add air during your dives shows you are probably well weighted, and have good buoyancy control

 

[inquis]

I think this is why people are inquiring as to whether you were too heavily weighted

I didn't interpret any of the above responses as suggesting the OP was over weighted. As I read them: a) under weighted but non-reserve gas weight compensates or b) correctly weighted but compensating for non-reserve gas weight by kicking or breathing at the upper range of lungs.

(ETA: and obviously several where c) not using the BCD is a good thing.)

 

[Belzelbub]

Which would mean dumping a little air, not adding it.

Yes. Dumping or venting air. When I dive without a wetsuit, I'll establish neutral at the beginning, and from that point, usually just need to vent some as the dive progresses. An exception would be if you start at one level, and then dive a bit deeper. May need to add a little at that new depth.

If he started neutral on the surface, with no wetsuit, it can be done without issue.

Wouldn't that be a bit underweighted at the end of the dive? Perhaps not enough to really make much difference depending on the tank capacity used.

 

[dmaziuk]

Wouldn't that be a bit underweighted at the end of the dive? Perhaps not enough to really make much difference depending on the tank capacity used.

With an empty Al-80 and no trim weights, I'd probably have to ascend feet-first, finning all the time, to maintain the 10m/min rate.

 

[parzdiver]

I often dive in the warm water with little or no air in my BC. Once, I did an entire dive, and when I got to the surface, I tried to inflate the BC and..... the hose wasn't even attached.

If properly weighted in warm water, that 5 lb swing can be handled with lung capacity.

 

[dmaziuk]

If properly weighted in warm water, that 5 lb swing can be handled with lung capacity.

Yes. It's about 5 times the average lings' tidal volume, but one can do it. One can also walk around in shoes 2 sizes too small.

 

[thomson_adam]

Sorry if I didn’t explain myself well

I was inflated on the surface and vented all air on the way down

After my safety stop and as my head was breaching the water I added some more in.

I was wearing 6lb of weights

 

[inquis]

For context, compensating for that 5 lb of gas weight with lungs alone requires inflating your lungs by 2.3 L more than normal. The average adult male has room for about 3.3 L of above normal inhalation (a.k.a., "inspiratory reserve volume"), so that's easily doable. Unfortunately, if you happen to have lungs like the average female with a 1.9 L inspiratory reserve volume, it ain't going to happen.

I personally find it vastly more comfortable to breath normally, so I choose to put that ~2L of air in my wing once at depth and just push the deflator button a few times during the dive.