Steel tank Wetsuit question

[MikeFerrara]

I shudder to think what would happen ff the boys on quest find out about the insparation.

Solo ice diving? I'm certain I have a better handle on the intent of DIR.

Big-t-2538,

I take students in overheads but I'm an ice, cavern and wreck instructor.

 

[Doc Intrepid]

MHK has provided valuable and constructive input to this board for a long period of time. Remember that. Issue raised, issue responded to.

This board has room for DIR and Non-DIR perspectives.

What this board does not need are self-appointed saviors who have recently come to preach the gospel to the unwashed heathens, while laughing to their buddies about our provincial ways.

Kane was spot on. DIR stands, or not, on its own merits.

I personally am pleased that DIR has managed to fill such large spaces in their lives that, obviously, were formerly vacant. How pleasant for them. Our recently-arrived saviors should seek other forums, though, or tone down their rhetoric. DIR does not benefit from arguments that aren't articulated very well to begin with, consist largely of slogans and invective, and are presented in a shrill tone that borders on near-hysteria.

Lets talk diving, but move on to other threads.

 

[Walter]

I'm not the same diver I was 20 years ago or even 5 years ago. I am constantly learning and adapting my style of diving to what I've learned. I also try to adapt my teaching style to provide a better class.

If MHK were frozen in time, I'd have much less respect for him. He has changed his techniques over time. Haven't we all? How can we fault him for learning and changing accordingly? It is a good way to be.

 

[Former FLL Now MSP Diver]

DIR Tec Diver once bubbled...
You also conveniently left out that George immediately replied that the person in the picture was an idiot and that picture was put up somehow when the site was out of his control.

Just two points of clarification.

I personally would not call Michael Kane "an idiot", and I'm surprised that some would call him one. I've always felt Mike's posts here very non-inflammatory and factual, and I've learned from them. Thanks Mike.

Second - the website is run by George's girlfriend, Pina Poceddu. I think he would have just a little bit of editorial influence over what goes on the website.

Thanks

Marc

 

[MWC]

To rephrase what Genesis and others pointed out earlier...

[bold]A given volume of air at standard temperature and pressure (1 atm, room temperature), say 150 cu ft, always has the same mass (weight).[/bold]

If you have a tank or tanks giving you 150 cu ft of air at STP, your change is bouyancy between empty and full will be the same to several decimal places, regardless of tank working pressure or material.
"Don't dive tanks bigger than [ital]x[/ital] cu. ft. with a wetsuit" should be a much better rule.*
Changing your weights when you change tank styles is a really good idea, of course.

Matt
*For metric lovers, just replace cu ft with litres. [ital]x[/ital] will vary with depth to the bottom, wetsuit thickness, and swimming strength.

 

[Se7en]

I think the suggestion should involve both thickness of wetsuit and size of tanks, as they both contribute to change in boyancy during a dive. And the composition of gas in the tanks

Wetsuit compresses. Loosing boyancy proportional to volume of neoprene

Tanks have mass proportional to total capacity

Helium is lighter than O2 which is lighter than N2

So, I know I'm OK in a 7mm wetsuit, with up to 160 cuft of air on my back. For other people the equation will be different - I know one guy who can swim up 200 cuft of air in a 7mm wetsuit.

So I'd suggest that there is no reason for a 'rule'. Everyone doing this sort of diving should be able to work it out for themselves. If you can't, then I do believe the label 'Idiot' may be appropriate...

As an aside, if I have a 6 lbs weight belt, or 6 lbs of air to dump, Im in favour of ditching the weightbelt... I like my air

Se7en

 

[Genesis]

So I'd suggest that there is no reason for a 'rule'. Everyone doing this sort of diving should be able to work it out for themselves. If you can't, then I do believe the label 'Idiot' may be appropriate...

As an aside, if I have a 6 lbs weight belt, or 6 lbs of air to dump, Im in favour of ditching the weightbelt... I like my air

First, if you are only six lbs negative, you can swim that up. If you can't, you shouldn't be in the water in the first place.

Let's assume instead you have 18lbs of gas - not implausible if you have on a set of doubles with Nitrox on them, and a set of HP120s doubled (which are -4 or so empty.)

You also have 10lbs of lead on you, to compensate for a thick, 2-piece 7mil wetsuit (along with your BP, which is -6.)

Now, you get to the bottom and the seam on your wing lets go, making it useless. You now have no buoyancy, and are something like -20 due to suit compression and the 18lbs of gas on your back.

There is no way in hell you can swim that up.

This is the "nightmare scenario" that people are talking about.

Now, you can drop the 10lbs of lead. But if you do, when you rise up you had better hope you haven't breathed more than 8lbs of that gas, because if you have, you're not stopping on the way up. That's not acceptable.

So, you get down there, have this problem, why not vent 10lbs of GAS? You still have more than 1/3rd of your gas. You can now swim up the rig, and more importantly, as you get near the surface your rig remains BALANCED, which means you can make a safety stop, control your ascent, and ONCE YOU GET TO THE SURFACE ditch your weight belt.

What good does the extra gas do you if you embolize due to an uncontrollable ascent?

Think outside the box folks. The 'one true way" mantra is BROKEN in these situations. You must ditch SOMETHING to swim the rig up, but why would you ditch something that will make you inescapably buoyant once you begin that ascent? That's STUPID! Instead, ditch something that you intended to get rid of during the dive ANYWAY, and that will NOT impact the balance of your rig.

You only have one thing that fits that description, and in this situation you have way more of it than you need with you.

 

[MASS-Diver]

Now this doesn't apply as much to me as I always dive dry, but, I think it could still have applications.

So, here's my question does anyone have a reason why Genesis's idea of ditching gas is NOT a good idea? Because it makes a hell of alot of sense to me.

 

[MWC]

MASS-Diver once bubbled...
Now this doesn't apply as much to me as I always dive dry, but, I think it could still have applications.

So, here's my question does anyone have a reason why Genesis's idea of ditching gas is NOT a good idea? Because it makes a hell of alot of sense to me.

The only problem I've been able to think of is freezing up a reg from the high volume of air flowing. Even that should be avoidable if you have the time to blow out short bursts of air, then let your regs warm up again.
Matt

 

[MWC]

Se7en once bubbled...
I think the suggestion should involve both thickness of wetsuit and size of tanks, as they both contribute to change in boyancy during a dive. And the composition of gas in the tanks

So I'd suggest that there is no reason for a 'rule'. Everyone doing this sort of diving should be able to work it out for themselves. If you can't, then I do believe the label 'Idiot' may be appropriate...

Se7en

Yes to both. I hadn't thought about the gas composition. I'm strictly a recreational diver.

By "this sort of diving" I assume you mean tech diving? I was thinking that such a "rule" would be aimed at less experienced recreational divers. Like the rules on maximum depth for dives. The recreational maxiumum is not an absolute maximum, but you need special skills and training to exceed it.
Matt