Decompression stop for shallow dives?

[dbulmer]

DetroitDiver
Thanks - I have a lot of practice ahead of me in the winter.

 

[detroit diver]

DetroitDiver
Thanks - I have a lot of practice ahead of me in the winter.

No problem. We all have some practice to do! The springtime can get really ugly if we don't!!

 

[BigJetDriver]

Hey, guys,

i don't mean to be grumpy, but can we stop hijacking this thread and get back to the discussion of the original question, please? :11:

 

[RichLockyer]

*IF* you are *perfectly* horizontal in the water, the air that is in the wing should be evenly distributed around the wing.

This is where you're wrong. This presumes a wing that is filled 100% to capacity. It's not, and never is... even surface flotation is more comfortable with it at 50% or so.

When the wing is used properly... IE: Not restrained by attachments to the BP, and not overfilled... the sides of the wing wrap the tank like a taco shell. This puts the butt-dump at the highest point.

I have no problem using the butt-dump wearing Skaana drygloves, and my dump does not have a bolo ball attached to the line.

 

[fmw625]

Where we dive has a silty bottom. We try not to stir the bottom because the vis goes to zero. There are times though when the bottom gets stired. First time in zero vis can be scary. Vis goes back to normal after a short while. Keeping up with buddy in zero vis can be a problem. We made buddy lines with snap bolts on each end. This helps when vis gets bad.

 

[Buoyant1]

I'll take it back to the subject at hand...My upcoming scenario... I'm going to be diving in the Keys the week of Thanksgiving...the inner reefs off of KW are primarily 25-35 feet deep the outer are a bit deeper... Since most of my dives will probably be within the 35 foot column, and given my noobie-ness of sucking air, there's no way I'll hit my limits and NEED to deco...the big question is .....wait for it.... SHOULD I?

Should I take a break at 15 and cool my heels or should I just keep a nice easy ascent and take it to the surface?

I guess the other question would be...what will my computer reccomend? the sim I did today to 35 for appx 40 minutes let me go straight up...should I assume that it will do the same in a real situation? (I'll be testing it for real in 3 weeks)


All good points will be taken under advisement....

Hey, guys,

i don't mean to be grumpy, but can we stop hijacking this thread and get back to the discussion of the original question, please? :11:

 

[ShakaZulu]

If you spend an hour at 35 ft, you can surface with no safety........have fun. I'll do a 3min at 10-15ft, just to help with micro bubbles. Suunto will give you a recommended safety indicator.

 

[jbd]

Because if you are perfectly horizontal, it's difficult to dump air as you ascend. If you can dump air while you are "horizontal", then you are not horizontal are you?

I use a jacket style BC. It only has one dump valve on it at the left shoulder. I have never had any trouble dumping air while horizontal.

I also have a fundamental issue with using breath control to ascend as you are filling your lungs, holding your breath and then waiting till you start to go up.

I use breath control exclusively on many of my ascents. At no point in time are you holding your breath. During the inhale phase there comes a point where you become slightly positively buoyant and you start ascending. As you start ascending you complete the inhale phase and start the exhale phase. Even though you have started to exhale you are still slightly positively buoyant and are becoming more buoyant as the air in the BC expands and you are still exhaling. During this exhale phase you will exhale enough to become slightly negative which will stop your ascent and now it is time to inhale again and repeat the process. At no time are you at risk of an over-expansion injury. There is no breath holding just proper timing of the respiratory cycle.

 

[BigJetDriver]

I'll take it back to the subject at hand...My upcoming scenario... I'm going to be diving in the Keys the week of Thanksgiving...the inner reefs off of KW are primarily 25-35 feet deep the outer are a bit deeper... Since most of my dives will probably be within the 35 foot column, and given my noobie-ness of sucking air, there's no way I'll hit my limits and NEED to deco...the big question is .....wait for it.... SHOULD I?

Should I take a break at 15 and cool my heels or should I just keep a nice easy ascent and take it to the surface?

I guess the other question would be...what will my computer reccomend? the sim I did today to 35 for appx 40 minutes let me go straight up...should I assume that it will do the same in a real situation? (I'll be testing it for real in 3 weeks)


All good points will be taken under advisement....

Bouyant1,

The essence of the meaning of NDL (No Deco Limit) is that one may safely surface without required stops IF one is within that limit.

There are NO guarantees, however, and the two main reasons that the agencies have included the safety stop in their training are these:

(1) to help control ascent rates, and

(2) for, guess what, SAFETY! (That is, it increases the margins of the safety envelope.)

In short, do you have to? The short answer is "no". Should you? The short answer is "yes"!

Cheers!

 

[TX101]

And when he's told that he's wrong, he just keeps pounding away.

And when you are told you're wrong, you just keep pounding away..

No one can visualise what I'm describing?

There are dump valves at either end of an air cell. For air to go out of a dump valve, the dump valve has to be at the highest point.

For the valve to be at the highest point you have to be off-horizontal. Either head slightly up or slightly down - otherwise the air isn't at the highest point!

I know it's completely pedantic, but unfortunately it's true.

I haven't even brought drysuits into the discussion because that illustrates my point further - you either have to roll to the right or raise your arm and drop your knees to get the exhaust valve to the highest point - same principle. And guess what? You are no longer horizontal!

Breath control, dbulmer you are right - you have to time it right. But what if you time it wrong? (which was my point)

Regarding SMB deployment.. I actually like to be a little negative and almost pull myself up on the SMB line for two reasons: (1) it keeps the line tight and makes sure when I deploy the reel the next time it's not going to jam and (2) It makes the SMB stand up on the surface, making you more visible.

Look, I've got no problem with ascending horizontally if the DIR guys call it what it really is: Looking cool. I'll admit, it's good practice for controlling buoyancy and if you can ascend horizontally properly, then you can honestly say you have mastered buoyancy control. BUT, saying it's superior to any other method just because you can flare out if you **** it up it complete bollocks in my opinion.

Sorry for the hijack, back to the topic at hand.