Ascent with little or no air in BCD??

[LanceRiley]

by the time i reach 50-60ft... i add air to my bc bout 1 1/2 mouthfuls.. I blow air instead of using the inflator...

I usually ascend slowly. usually when im on my way back.. a minute at 50.. a minute at 40 .. a minute at 30... while doing this.. I release air little by little.. to stay neutral... by the time im 20 i will have very little air to none in my bc. depending on my air in the tank. but at 500 psi... i definitely have no air in my bc..

 

[boulderjohn]

OK, let me get this straight; you are 16 years old, you play soccer, swim and ski, yet with a pair of very powerful open heel scuba fins swimming up from 55' with no air in your BC "became very tiring very fast."

In no particular order, here's my questions; where did you get scuba certified, what exposure protection are you using, what is your height/weight, how much weight were you diving with, what kind of tanks were you using, what kind of tanks were you certified with and what psi were those tanks on each ascent described above???????

Wow, such a hostile tone directed at a 16 year old beginning diver who came here hoping for some help.

He already told you where he was diving. It took me about 10 seconds on Google to find this:

Water temperature: In the summer, 70 degrees Fahrenheit (21 degrees Celsius) above the thermocline and 42 F (5 C) below the thermocline, which is at about 30 feet (9 m).​

So at the end of September I am going to guess that at 55 feet he was maybe diving in 38° water.

I am going to hazard a guess that he was probably wearing a thicker wet suit, experiencing more suit compression and subsequent decompression, and carrying a lot more weight than you have experienced in your lifetime of diving Key largo and Hawai'i. You probably do not realize what a difference that makes. Having some experience with cold water diving and the buoyancy problems inexperienced divers have with it, nothing in what he wrote surprises me at all.

 

[Tigerman]

I can only say one thing for sure..
I get a whole lot more tired diving locally than diving tropical and its definetly not because I magically get into better shape while sitting on the airplane..

As for the topic, start ascending when you're neutral and dump air as you go up. You do right in not "taking the elevator" though, but staying neutral you can adjust your ascent by finning and breathing a lot easier.

 

[dumpsterDiver]

I'm glad you can draw such concrete conclusions from a single sample of Navy divers. Are you a government statistician?

n= 1. Strictly anecdotal.. but i have been waiting 30 years for the right time to say the only time i ever dove with a navy diver... he sucked...

 

[Tigerman]

It might be that it should be "the only guy I KNOW was a navy diver sucked"..

 

[String]

Ascend *neutrally buoyant* by just trickling air out. Certainly do not make yourself negative and swim up. That isn't safe.

Also, forget the computer. Leave it on the shore for 30 or so dives. Its scary now how many people are completely unable to ascend at a safe rate without a computer showing a graph or beeping to tell them. Learn to do it without that.

 

[Hawkwood]

Wording and comprehension is everything.

Just finished OW dives 1 and 2 yesterday. I had two students which made it a treat. On our first ascent I watched one ascend with his finger at the ready over the dump button as he began. The other proceeded to dump all his air right away.

Eventually they made it to surface, with one struggling a good chunk of the way - you can guess which one.

During the debrief we discussed the ascent. I asked why he dumped all his air. His response was they were told something along the lines of "to release the air from their BCD on ascent". The other student jumped in with, "if needed to slow down".

Both were told the same thing, yet both "heard" something different.

 

[tr3a]

Wow, such a hostile tone directed at a 16 year old beginning diver who came here hoping for some help.

He already told you where he was diving. It took me about 10 seconds on Google to find this:

Water temperature: In the summer, 70 degrees Fahrenheit (21 degrees Celsius) above the thermocline and 42 F (5 C) below the thermocline, which is at about 30 feet (9 m).​

So at the end of September I am going to guess that at 55 feet he was maybe diving in 38° water.

I am going to hazard a guess that he was probably wearing a thicker wet suit, experiencing more suit compression and subsequent decompression, and carrying a lot more weight than you have experienced in your lifetime of diving Key largo and Hawai'i. You probably do not realize what a difference that makes. Having some experience with cold water diving and the buoyancy problems inexperienced divers have with it, nothing in what he wrote surprises me at all.

Well Said

 

[DivemasterDennis]

The original question raised here is a good place to review a proper ascent. First, as throughout the dive, you should be neutrally buoyant for the ascent. Mndiv and buddy were not maintaining neutral buoyancy on the dive or they would have had no trouble maintaing a constant depth, and the ascent would have been controlled. Next point of review: as you ascend, vent air from the bc as necessary to maintain neutral buoyancy. That means that you will hold the low pressure inflator-deflator above you head throughout the ascent (or at shoulder level at least). Venting all air before commencing the ascent is NOT the way to go, unless that is needed to be neutrally buoyant. All of this is easiest when you are properly weighted. Overweighting means you will constantly have more air in your bc than if you were weighted properly, and that air will expand and contract with depth changes and greater impact on buoyancy than a smaller amount of air in the bc would have. During the ascent, 30 feet per minute is a really good rate. There should never be an occasion when you "race" to the surface. During your ascent, kick slowly and easily, trimming buoyancy constantly. With more diving and underwater time, you will become more proficient with maintaining neutral buoyancy at all times, including during ascents. Your safety stop ( which you did not mention doing, but should after any dive over 25 feet, ) should be at neutral buoyancy, so can can just "hang there" without kicking. If at the end of a dive with a mostly deplete tank you can hover motionless at 15 feet, with little or no air in the bc, you are properly weighted. Be safe, be an active diver, and consider taking a peak performance buoyancy class (from a different instructor) at some time in the near future.
DivemasterDennis scubasnobs.com

 

[RTee]

The aim of the manoeuvre is to ascent or descent in a controlled manner.

Interesting to see how many folks develop pain in their ears just by doing pool work as part of their OW training...just by sinking straight to the bottom. On my first trip to Cozumel I referred to individuals who plummeted from surface to the bottom in 85 fsw as craterers. The only thing they were attempting to do was to equalize their ears in a fast and furious way on the way down and only after they had cratered themselves on the bottom that they would start inflating their BCD.

While you do not use your BCD as an elevator, adopting the technique mentionned by TSandM and others will initiate an ascent that you then need to control through exhaling and gradually releasing air from your BCD and or drysuit on your way up. When I did my refresher I recall being told to empty my BCD...fine in a shallow pool but not so practical from 60, 100 and 150 ft. I eventually emulated experienced divers I dove with.

Going back to my AOW manual, it seems it recommends ascending and descending using a reference line if possible. In low vis conditions...green and brown water, if lacking visual references and in the absence of one....create one by deploying a SMB right from the bottom . Before leaving the bottom, inflate a SMB and then slowly follow the line up (as you respool it) to the surface. I have also seen some folks putting a galvanized washer at the 15 foot mark for safety stops.

Eventually, you might be able to better use the environment to acquire visual references. I was initially taught to not go up quicker then the smallest bubbles I could see. Some people will also use particles in suspension in the water as a medium to judge their ascent. Having a wrist mounted computer also helps big time. In my case, because I rarely use dump valves to release air out of my wings, I will have the computer on my right wrist and use my left hand to deflate or inflate my Wing...but that is me. So to each their own. I suggest you experiment.