How to move double tanks around easily and safely---DIR needs to address this!

[Scarborough Diver]

My only issue with this particular statement (and I think your other comments on lifting are all spot on) is that for many newer divers, and especially those who have yet to take C1 or T1 (yes, this includes those with a Fundies tech pass), doubles do NOT offer much, if any, redundancy. Fundies simply does not cover failures. All it teaches (at the tech level) is how to do a valve drill. If you've ever seen the first two days of a T1 class, you'll immediately recognize that there's a country mile between doing a valve drill and team diagnosing and solving a real failure.

IMO, many divers grossly over-estimate their capacity to deal with failures on the basis of simply owning doubles (or learning about valve drills). All that adding doubles does is *increase* the number of failure points on your back. It's only once you *and* your team learn to manage that hardware (C1/T1) that you gain actual redundancy.

Very good point. It's essential to have proper training on not just the shutdown procedure, but the diagnosis of the problem. Also a buddy that can help diagnose is crucial.

 

[Tristan.ak]

As with lifting anything heave it all comes down to using your head and thinking about how your going to lift it. Hay bailes, asphalt shingles, bricks, sand bags, and strippers. Its all the same idea of lifting with your knees not with your back, ask for help if you cannot carry them around. I don't see what the problem is, more classes for basic lifting concepts?

 

[danvolker]

Dan, I don't think this is a GUE thing. I think it's a Florida thing.

Errol posted a long and very eloquent plea for double tanks not long after our trip out there. I wrote to him about it, because I thought it was overkill. His answer was clear: Where HE dives, the dives are deep, and the rental tanks available are Al80s. Rock bottom on an AL80 for a 90 foot dive means you get a very short dive. Since larger tanks aren't an option, doubles are the only other answer. Even if big steels were available, you run into the "heavy tank with no redundant buoyancy" issue.

Where WE dive, you need so much ballast that a tank which is 2 or 3 pounds negative when empty is absolutely DELIGHTFUL. HP100s and HP130s are very common tanks for divers in Puget Sound, so people just don't need to move to doubles early, or often at all. Even our deepest and longest dives (remember, we're thermally limited ) can be safely done on 130s -- you really have to get into staged deco before doubles are really necessary.

I have never heard a GUE instructors on the West Coast insisting on doubles. In fact, I had dinner last night with one of the Monterey instructors, and he was expressing his frustration with the apparent "culture" of doubles that has grown up there, moving divers into those setups before their platform is really stable, and well before they need either the redundancy or the gas.

It's your particular environment -- it's not a global GUE thing.

Hi Lynne,
You may very well be right that this is a Florida evolution or "mutation"

Unfortunately, I have to deal with it because I am in Florida.....and I like recreational divers to be exposed to DIR ideas...I'm not a huge fan of doubles for shallow dives-they are too much of a pain in the rear end.
This thread can still help the Florida issue, and it covers an area I never paid much attention to. For me, or for Errol, and many of the GUE instructors, the weight of doubles is only a mild annoyance--it never really required any "solutions".
Suggestions which have already appeared here are going in to my "arsenal of common sense solutions" I can use for Florida divers with this problem in the future, or for women divers who are close to half the body weight of many of us...

Thanks again for your perspective.

 

[aquaregia]

So long as one is wearing at least a 3mm wetsuit I cannot see where utilizing a 100HP cylinder would cause a diver to be over-weighted. Faber is -1lbs, Worthington -2lbs.

My 3mm wetsuit has 7# lift in fresh water, so call that 5# of lost buoyancy at 100'. Add to that 8# for the gas and you're potentially 12# negative for a wing failure at depth with full gas.

 

[Blackwood]

As with lifting anything heave it all comes down to using your head and thinking about how your going to lift it. Hay bailes, asphalt shingles, bricks, sand bags, and strippers. Its all the same idea of lifting with your knees not with your back, ask for help if you cannot carry them around. I don't see what the problem is, more classes for basic lifting concepts?

Down here we call lifting strippers "abduction," so you definitely need to think it through.

 

[Tristan.ak]

Down here we call lifting strippers "abduction," so you definitely need to think it through.

Yes that is correct, I ment carry around or something. Still I wouldn't pick up, carry, or lift anything close to a stripper.

 

[rjack321]

Still I wouldn't pick up, carry, or lift anything close to a stripper.

Why not? They are a good workout all around

 

[elan]

Believe me, it's not my way...I think DIR for a nitrox dive to 100 feet is an hp 100 and a good DIR buddy....And I will not be using a set of doubles for this kind of dive, ever.
Then again, my buddies are all very good divers, and we all have very low SAC rates.

I think this is a direction that is being pushed to the hoovering masses....ask Bob Sherwood his take on at what depth, and what diver, for doubles..

One thing I do agree with the GUE position on...the aluminum 80 was fine fore doing 100 foot dives prior to nitrox--back when everyone dove air...But now with the durations desired by most for the 80 and 100 foot nitrox dives, an al 80 is just a very bad choice...



With good sac rate and good buddy, the hp 100 should be fine...with a poor buddy and mediocre sac rates, maybe the 130 size or the doubles are called for.

Well lets see here in Canada as you hit the cold water your tank cools down an you find yourself short of 10cuf in the hp100 given rock bottom of 40 cuf you have 50 cuf left divide that by 4 you have 12 cuf at 1 atm. If you have 25 mins on the bottom on 32 you need a sac of .5 and that is not counting the accent. If you add accent your required SAC will be in a range of .4 and that is for a colsd water. I can hardly call this hoovering.

My point is you are making too generic of a statement.

I usually use up the whole stage + a bit of the backgas on this kind of dive which is roughly 80 - 85 cuf all together. Add the rockbottom an you end up in 130 realm. If i end up there I would prefer to dive double lp72 than single hp130

 

[Scott L]

My 3mm wetsuit has 7# lift in fresh water, so call that 5# of lost buoyancy at 100'. Add to that 8# for the gas and you're potentially 12# negative for a wing failure at depth with full gas.

I went with the recomendation of the Dress for Success book and when my suits required replacement had custom suits made utilizing G-231N, which are advertised to compress less than standard neoprene.

I would be interested in comments from those with first-hand knowledge exactly how much the material would compress at 100'. Regardless, I am not shlepping doubles for recreational NDL dives here in S. Florida...

 

[elan]

As per redundancy. If you put the second diver, that has his reg flowing, on the same first stage through the octo in a 35-37f water chances that you will have another freeflow are very high. So that calls for a second reg on a pony or an h valve. I would rather have doubles.