Buddies kept grabbing/pulling me to ascend faster than computer said was safe

[Diver0001]

Seriosly????? Where did you find this smoke to blow out your butt?

Resulting from a thorough understanding of deco theory.

Question for you, since you don't seem to understand it..... At what point is an ascent so slow that it becomes a multi-level dive? No theory spinning... Give us a number.

R..

 

[Water Boy76]

My OW Instructor told me to dump all air in our BC's before ascending. He told the entire class multiple times. If I remember, he said it makes for a slower more controlled ascent.

I'm not sure if it was just his opinion or in the manual. If I cared, I would review the NAUI manual and see if it's in there. I don't.

 

[Diver0001]

My OW Instructor told me to dump all air in our BC's before ascending. He told the entire class multiple times. If I remember, he said it makes for a slower more controlled ascent.

I'm not sure if it was just his opinion or in the manual. If I cared, I would review the NAUI manual and see if it's in there. I don't.

Not the manual.

It was probably your instructor's practical solution to a common problem. It was also the wrong solution, imho.

Suppose you're diving along a wall with an endless depth. I know a few places like this. Telling people to "go max negative" before an ascent would be exceedingly dangerous where the diver does not have a "hard bottom".

R..

 

[chrisch]

My OW Instructor told me to dump all air in our BC's before ascending. He told the entire class multiple times. ..

I find it depressing that new divers are still being taught nonsense in 2015.

 

[Jack Hammer]

Seriosly????? Where did you find this smoke to blow out your butt?

Not smoke, if you look into deco theory, especially advanced deco theory, too slow can become troublesome the deeper you go. And not just on deep staged decompression technical dives with mixed gas. For most shallow recreational dives its not as pronounced. [emoji2]

 

[boulderjohn]

Seriosly????? Where did you find this smoke to blow out your butt?

Here's my advice: When you don't know what you're talking about, try not to be ridiculously rude when attacking people who do.

This has already been discussed. Ascending too slowly allows the slower tissues to build up nitrogen too much while the faster tissues' off-gassing slows down to an almost meaningless level.

Faster tissues: They will off-gas at a rate that depends upon the pressure gradient between them and the gas being breathed. If you ascend too slowly, they will approach and even equilibrium, meaning they will stop off-gassing.

Slower tissues: They will continue to on-gas as long as the nitrogen pressure in the gas being breathed is greater than in the tissues. Stay there long enough, and they will reach equilibrium, and you will need to deal with them later in the ascent.

There have been some recent threads about this in relation to the growing disenchantment with deep stops. Doctor Simon Mitchell, one of the world's foremost authorities on decompression theory, participated heavily, explaining all of this. You might want to check it out.

 

[Jack Hammer]

Something to consider regarding the other divers the OP mentions. If the OP was breathing heavily and had difficulty starting the ascent and seemed agitated, they may have interpreted the OP as being near panic and just wanted to get the OP to the surface quickly. I don't condone dragging divers up, but I have been in situations where Ive personally had to do just that. (diver went OOA, Diver froze up - near catatonic, etc). Just something to add to the conversation

 

[Crowley]

My OW Instructor told me to dump all air in our BC's before ascending. He told the entire class multiple times. If I remember, he said it makes for a slower more controlled ascent.

I'm not sure if it was just his opinion or in the manual. If I cared, I would review the NAUI manual and see if it's in there. I don't.

I don't want to stray too far off topic but it's wrong. You start an ascent neutral and release air as you ascend, not dump all air then start an ascent. If you're wearing a thick exposure suit, or drysuit, which requires a lot of weight, then ditching all your air at depth means you will be excessively negatively buoyant, and you effectively have to swim to the surface using fin power only, carrying that weight with you. If something were to go wrong, you would sink.

I don't have a copy of the new OW manual to hand but here is a good example from the PADI AOW Peak Performance Buoyancy Dive Knowledge Review, question 4:

4. Place a check next to those instances in which you need to adjust your buoyancy during a dive
- to compensate for buoyancy changes as you use your air
- to compensate for buoyancy changes due to expose suit protection
- to begin an ascent
- to compensate for increased buoyancy during ascent.

The correct answer is a, b, d NOT c.... that's the first reference that pops to mind. I don't know about other agency stuff but I would assume it's similar.

Back to the topic - It's possible that this is what was slowing the OP's ascent - and boulderjohn is right, you don't have to keep the ascent rate monitor at the smallest level possible, just not exceed it. Still no excuse for dragging divers around though.

Whilst I'm here - yes, according to decompression theory you are still technically on-gassing as you ascend. Parts of the "theoretical body tissues" absorb nitrogen quickly, others more slowly - and it is this rate of absorption which is important. For the "slower" tissues, the rate of absorption might decrease, but on-gassing still occurs. Think of it like a balance - a long pivot like a see-saw which has - random numbers - 50 kilos at each end. Add 10 kilos to the right hand side and the that side will descend. If you put a ball on the left end, it will roll downhill to the right. As it's rolling, add 11 kilos to the left - the left hand side now weighs one kilo more than the right and although the right hand side will now start to ascend, the ball will keep rolling to the right hand side until the balance point is reached and it changes direction. That's an imperfect analogy but a good one - the right hand side of the balance (the diver) is ascending, but the ball is still rolling towards it (on-gassing).... until it ascends far enough for the pressure imbalance to change direction. If you see what I mean.

Cheers n beers

C.

 

[boulderjohn]

The instructor who told you to dump all your air before ascending should be shot at the post. Are you sure you have not been confused on the direction he/she gave?

Unfortunately, this instruction is indeed given to many divers. When I was a new DM, I heard a Course Director tell new OW students to do that. When I was leading a group trip to Belize, a veteran DM gave those instructions to our group before our first dive together. I assume that advice was part of his regular dive briefing to all groups all year long, year after year after year.

What do the two have in common? Neither had any experience other than warm water diving in 3mm wet suits, hopefully close to properly weighted. That system will actually work under those circumstances.

When I was a new instructor, I conducted an AOW course with a student who had just moved to our area. She was wearing a 7mm suit and hood for the first time. With a 7mm suit, you need enough weight to descend from the surface, but once you are at depth, the suit compresses to the point that you don't need all that weight. When I signaled for the ascent on her first dive, she immediately dumped all her air and began to sink. That taught me an important lesson, and from then on I have assumed that all divers have received this bad instruction, and I make proper ascent technique a part of all briefings with divers I did not myself teach originally.

 

[redacted]

Seriosly????? Where did you find this smoke to blow out your butt?

Nonsense. How about an ascent at 1 ft per minute from 90 ft? Extreme example - yes.

How about 5 ft/min? 10 ft/min? 20 ft/min?

Draw the line where you want and include it in your dive plan. I normally plan 60 ft/min from depth and 30 ft/min in the approach to the RS and the surface; and usually include a 30 ft stop for deeper dives involving higher gas loading. My buddy knows my plans.