Ascending without BC's deflation / inflation

[Den7]

Dry suits and thick wetsuit are a lot more difficult to manage but that is an overstatement. Nobody with 5 dives is a buoyancy god in a drysuit...for that matter, no one with 100s of dives but only 5 in a drysuit has it mastered. I have seen divers with a lot of "experience" who have no clue what buoyancy or proper weighting is all about but then again there are plenty of warm water divers who are masters of buoyancy control. I dive the entire range from dry to no wetsuit at all and work on my skills on every dive. It's an ongoing process that I try to improve on with each dive.

Good point. I am not advocating for the fact that 5 dry suit dives might make one master buoyancy control. I simply compared the difference of dry and wet by referring to someone's statement.

 

[Den7]

You can attach the tank to a back pack with the BC removed, harness or back plate. Hanging at a decompression stop is not a problem. You can check out this site for tank bouancy when both full and empty. Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan

Thanks for the link.k:

 

[coolhandcarter]

As a rule you should always empty your BC completely before you start you ascent. And during your ascent you should continue to try to release air to account for expanding air inside your bladder during ascent. Failure to do so could result in an uncontrolled and buoyant ascent. The only time you should be adding air to your BC is for minor buoyancy adjustments and when on the surface (such as starting and ending a dive).

 

[Bubbletrubble]

As a rule you should always empty your BC completely before you start you ascent. And during your ascent you should continue to try to release air to account for expanding air inside your bladder during ascent. Failure to do so could result in an uncontrolled and buoyant ascent.

If a diver completely empties his BCD, then there won't be any air inside the BCD during the ascent, right?

I disagree with the empty-your-BCD-completely-before-ascending philosophy. Consider that a drysuit is another buoyancy compensation device. No one advocates squeezing out 100% of the gas inside the drysuit at depth to protect against an uncontrolled, buoyant ascent. Most drysuit divers just set their exhaust valve to automatically dump and ascend under control, dumping gas from inside the suit as necessary. No big deal. (Yeah, I realize that dumping gas from a drysuit in an emergency might actually be easier than from a BCD, i.e., pull open neck/wrist seal.) I suppose that's why I don't feel compelled to dump 100% of the gas inside my BCD prior to ascending. I begin my ascent at neutral buoyancy and simply manage the BCD bubble by dumping gas from the BCD as necessary on my way to the surface.

The only time you should be adding air to your BC is for minor buoyancy adjustments and when on the surface (such as starting and ending a dive).

Around here, divers have to wear substantial exposure protection (drysuit or thick wetsuit). Assuming that a diver is properly weighted and wearing a thick wetsuit, he'll probably find himself adding a substantial amount of air to his BCD during the course of a dive, particularly at the beginning of a dive (full tank) and if his dive profile is rather deep (100+ fsw or whatever depth significantly compresses his wetsuit).

Dive conditions vary across the globe. Certain environmental factors, e.g., water temp, can influence gear choices and how a diver conducts his dive. This includes how much gas he decides to keep inside his BCD at any given time.

 

[dumpsterDiver]

As a rule you should always empty your BC completely before you start you ascent. And during your ascent you should continue to try to release air to account for expanding air inside your bladder during ascent. Failure to do so could result in an uncontrolled and buoyant ascent. The only time you should be adding air to your BC is for minor buoyancy adjustments and when on the surface (such as starting and ending a dive).

Total BS....

when a diver wants to initiate an ascent they should do NOTHING with their BC. They should just begin a gentle kick upward or maybe even a slightly deeper breath. That should be enough to start an ascent if they were neutral and then the diver can dump a small amount of air as needed.

To say that a diver should vent their BC before an ascent is retarded. To say that they should never add air on ascent is also ridiculous..what if the diver vents too much on ascent? Then they should obviously add some air to ensure that they are very close to neutral for the ascent.

 

[Charlie99]

As a rule you should always empty your BC completely before you start you ascent.

Why??

 

[Den7]

As a rule you should always empty your BC completely before you start you ascent... .

Disagree! If you dump all your BC air before you initiate your ascent you might crash into the bottom first (if the bottom is close enough) then start swiming up from being negatively buoyant. This is basically done by newbie divers who are afraid of runaway /uncontrolled ascents and prefer wearing themselves out by physically swimming and possibly ending up breathless at the surface (depends on how fit you are as well) instead of doing it the right way and slowly hovering up.

 

[Rich Keller]

Den7, If you weight yourself so you are neutral buoyant at the surface with a full tank and an empty BC you should end up by the end of you dive just slightly positive when you are leaving the bottom. From there you may have to swim a bit at first but as the pressure decreases and your suit starts to expand you should end up close to the assent rate you are looking for with you having to make only minor adjustments to get exactly where you need to be. This will depend on the size tank you are using, the suit you are wearing and how deep you are but for most applications this should be the case. This has the added benefits of reducing the overall amount of air you use in a BC that could be better used to extend your bottom time and in the case of the BC failing you will not be overweighted but at that point you will have to do it the old fashioned way and swim to the surface.

 

[dumpsterDiver]

Den7, If you weight yourself so you are neutral buoyant at the surface with a full tank and an empty BC you should end up by the end of you dive just slightly positive when you are leaving the bottom. e.

WRONG< WRONG< WRONG Where do you seemingly experienced people come up with this garbage? Suit compression will make the divre negative at the bottom if they are wearing a full thick suit. To assume otherwise and make generalizations as above is equally retarded.

 

[Garth]

I agree with dumpsterdiver. What happens when you turn a dive before you use all you planned gas. You would then still be very negative if you dumped all the air out of your bladder.
I have learned a few things in life and when someone says you should "always"... Is usually BS. And this discussion is no exception.