acending?

[HPT3]

If one is neutral during a dive and begins to make an ascent, should a small amount of air be added to the BC to assist the ascent, then begin to release the air as needed when one becomes more shallow? Or should a diver swim upwards and let the air expand naturally, venting as needed?

 

[Padipro]

Your BC should never be used as a lifting device. Swim up and vent as required to control your ascent.

Scott

 

[jbd]

Padipro about not using the BC and that the method he mentions will work. I would like to add one idea for your consideration though. If you are neutrally bouyant all you need to do to begin an ascent is simply inhale. It has the same effect as adding air to the BC and has the added benefits of being very easy to control and requires no body movement i.e. no arm, hand leg or foot movement. When you want to stop or slow the ascent simply exhale.

 

[cdiver2]

inhale-ascend sounds like a recipe for trouble to me

 

[Wendy]

jbd once bubbled...
Padipro about not using the BC and that the method he mentions will work. I would like to add one idea for your consideration though. If you are neutrally bouyant all you need to do to begin an ascent is simply inhale. It has the same effect as adding air to the BC and has the added benefits of being very easy to control and requires no body movement i.e. no arm, hand leg or foot movement. When you want to stop or slow the ascent simply exhale.

Ok it sounds to me that you are trying to describe using your lungs to control bouyancy, but its coming out like you are saying to hold your breath during your ascent, which we all know is a BIG no-no.

Can you explain your post a little better for those new divers out there reading it?

 

[CincyBengalsFan]

JBD,
"Simply exhale when you want to stop or slow the ascent"???

Please tell us you're not telling this person to HOLD THEIR BREATH?

Everyone knows that gas will expand as we ascend right? Your lungs can only take about 2 PSI of overpressurazation whichis roughly 4 ft of ascending....

This is very dangerous information to give out as many new divers read these posts.

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You have many ways to make a slow safe ascent...One is the simply use of those big ole expensive fins you bought for scuba. A couple of kicks and your on the way up.

As far as using your BC. Some agencies teach this. NASDS/SSI has taught this method with obvious success.

However; I don't recomend this method, at least not until your an extremely good diver.

I would just let your BC naturally expand then start to dump air out slowly. Use the BC as an assistant but not as the full time submarine.

 

[jbd]

I re-read my post and see that I have not been very clear. Indeed this is not a breath holding technique at all. With a deep or full inhale a diver who is correctly neutrally bouyant will begin to ascend. This will be very slow and when the diver exhales the ascent will slow even further and then stop. With sufficient exhalation the diver will begin to descend--again very slowly. The distance that is travelled in this ascent with practice can be as little as 2 to 3 inches, which is far less than is required to cause overexpansion injury to the aveoli.

As Boyle's Law tells us, the air in our lungs will expand as we ascend. The idea here is to be at a point that you are ready or capable of exhaling that expanding air as a part of your regular breathing pattern during your ascent.

One of my students this summer had to miss a regular pool session and the time was made up during a one to one lesson. At the end of that pool session she could use this technique to ascend and then descend in 4 inch increments at the side of the pool. Each increment allowed a stop for two respiratory cycles before making the next move. Its not hard to learn or teach.

 

[CincyBengalsFan]

HPT3,

To actually answer your question and not blow my own whistle to much..........

If you are neutrally bouyant like you said. Then after a kick or two upwards...Your BC will start to expand and possibly cause you to ascend faster. So I would start the ascent with the use of fins to keep it under control then slowly vent the BC using it at a minimum for and during the ascent.

In my 7 1/2 yrs. of teaching for 5 agencies this method is easily learned and taught. I've been a certified diver for over 20 yrs. now and this is a great method for ascent.

Others may have a better ascent method but this works for me and my students and dive buddies.

 

[cantlogon]

I'm always using my lungs/breathing to make minor adjustments in bouyancy. This is NOT holding my breath, or taking a huge breath to compensate for being overweighted. Just breathing in a bit more if I want to go up, exhaling a bit more if I want to descend. All of this is done after neutral bouyancy has been established. The airway is never closed during this...basically, inhalation & exhalation is just stretched out sloooooooooooower than normal.

I feel a couple of advantages to this are 1) diver can alway "find" his/her lungs...unlike BCD inflator hose and 2) diver rarely mistakes "in" button for "out" button when inhaling/exhaling. I guess I should add that most of my diving is in tropical, no wetsuit water....so fine-tuning buoyancy by breathing is more practical than if you have a 5mm wetsuit, where bouyancy would vary considerably with depth, and you'd have to adjust your BCD air more often.

In a lot of visiting divers here (in Guam) I see the problem of being overweighted & constantly having to play with the BCD....a.k.a. "elevator divers." Sink too deep, kick frantically to ascend, then float to the surface before they can find/use their inflator. As with shampoo, repeat. Guiding these divers usually means I get back on the boat with almost 1/2 a tank left because they've burned through their air so quickly. (of course I'll try to give them some advice on proper weighting or even adjust their weights "mid dive" if necessary...a lot of divers only dive a few times/year, so you can't expect them to have perfect buoyancy )

Chris

 

[CincyBengalsFan]

cantlogon once bubbled...
I'm always using my lungs/breathing to make minor adjustments in bouyancy. This is NOT holding my breath, or taking a huge breath to compensate for being overweighted. Just breathing in a bit more if I want to go up, exhaling a bit more if I want to descend. All of this is done after neutral bouyancy has been established. The airway is never closed during this...basically, inhalation & exhalation is just stretched out sloooooooooooower than normal.

I feel a couple of advantages to this are 1) diver can alway "find" his/her lungs...unlike BCD inflator hose and 2) diver rarely mistakes "in" button for "out" button when inhaling/exhaling. I guess I should add that most of my diving is in tropical, no wetsuit water....so fine-tuning buoyancy by breathing is more practical than if you have a 5mm wetsuit, where bouyancy would vary considerably with depth, and you'd have to adjust your BCD air more often.

In a lot of visiting divers here (in Guam) I see the problem of being overweighted & constantly having to play with the BCD....a.k.a. "elevator divers." Sink too deep, kick frantically to ascend, then float to the surface before they can find/use their inflator. As with shampoo, repeat. Guiding these divers usually means I get back on the boat with almost 1/2 a tank left because they've burned through their air so quickly. (of course I'll try to give them some advice on proper weighting or even adjust their weights "mid dive" if necessary...a lot of divers only dive a few times/year, so you can't expect them to have perfect buoyancy )

Chris

Okay...So please let's look at the guys ORIGINAL QUESTION and see if we can stick to it. I've always taught to breath normally throughout the dive and especially when ASCENDING. But do you guys think it's Okay to take in a deep breaths and shallow exhales FOR ascending?:drown:

Use breathing techniques for proper bouyancy sure but not for ascending to the surface...:reaper: :dead:

Best rule of thumb is to teach students to breath normally underwater first then work on the advanced skills.:scuba: