Diving with a steel tank and a wetsuit??? A dangerous idea?

[AbyssalPlains]

He then went on saying that you should only dive with a steel tank if using a drysuit. And added again how much of a fool I was

HE is the fool, not you. I've been diving for over 15 years (mostly in Europe), and before I moved to the US, I had seen an alu tank ..um.. maybe once. Just recently, I dove the Keys and guess what they had on the boat...

The difference in buoyany between a 80 cubic-foot-alu tank and a steel tank of comparable size is 4 Lbs, i.e. noticeable, but certainly not enough to make a difference between life and death. The guy didn't know what he was talking about.

 

[jefffalcone]

I'm no expert, but wouldn't you be swimming up both the swing in the tank (say 6 lbs) and the compression of the wetsuit? How much does a 7 mm farmer john compress at say 90 fsw?

Might want to try to swim up slightly more than 5 lbs

I don't dive a farmer john, but with a fully compressed 7ml onepiece properly weighted using a HP100, I am able to stop my descent just by taking a very deep breath. I estimated this to be about 5 lds. I guess my lungs could provide more lift than that. If you really want to be sure swim up with 10 lbs of lead. Either way I think you'll convince yourself that it can be done.

 

[TSandM]

What I have heard is that a 7 mil wetsuit could have as much as 23 lbs of positive buoyancy, of which it will lose almost all at 100 fsw. If you are using aluminum tanks, they are positive when empty, which means you're carrying weight to sink the empty tanks. If you're diving steels, you're letting the negative buoyancy of the empty steel tanks contribute to sinking your wetsuit. That's weight you can't ditch. The weight you are carrying to sink your aluminum tanks IS weight you can ditch, assuming you have it somewhere you can ditch it. So it will be much easier to get back to the surface in the event of a wing failure at the beginning of the dive, if you are diving aluminum tanks.

Frankly, if you're diving that deep, a redundant buoyancy source (i.e. dry suit) seems like a good idea to me.

 

[Cummje]

Sheesh, where I'm at I can't even get Aluminum tanks. We only dive steel. And half the year people are in shorties.

 

[DiveNav]

What I have heard is that a 7 mil wetsuit could have as much as 23 lbs of positive buoyancy, of which it will lose almost all at 100 fsw.

Actually it is even more than 23lbs, but it will never lose it all; in fact the non-compressible component of the overall buoyancy is quite substantial.

Assuming that the diver was properly weighted (Amount of weight should be enough to allow diver to: a) Sink when tank is full and BCD is empty and b) Maintain 15ft safety level with tank @ 500PSI) .... and assuming that the diver does NOT drop his weights when is down 100ft (bad bad bad idea .....) the problem then is reduced to few questions:

1) Can the diver generate enough thrust to swim up?
2) What is the fitness level of the diver? Can he endure the demanding task of swimming up till the surface?
3) Does the diver have enough air in his tank to reach the surface?

For your info, research papers show that answer to 1 is yes for the "average" (male - fit) diver ....

Suggestion .... if you normally dive HP100 with a wetsuit you should probably test if you can answer yes to all 3 questions .... make sure that you have few buddies around watching you and plenty of air in the tank.

Best Regards,

I_AM

 

[nereas]

I am editing my own post because I think the spirit of the original question is getting lost... I don't really care to know if the guy was an idiot.... I would like to hear from experienced divers as I feel there is a possible safety issue we (the less experienced divers) can all learn from:

So here is the re-phrased question:

On a deep dive (at least under 100ft) with a 7mil suit and a single Hp steel tank,
1/ if your bc fail can you make it back safely?
2/ what would be the safest procedure to do so? I assume you probably would have to let go of some of your weights...

We will assume your body isn't around, you don't have a lift bag and you were properly weighted when going down.



I am reposting a question which was posted on the DIR forum yesterday. I was asked to re-post it elswhere. So here it is for the second time (sorry):

An interesting story happened to me today and I really would like to get the DIR/tech divers opinion on the subject.

I have been needing a float for my L.A County ADP class and found a very good one at a good price on craig's list. I called the guy, we agreed on the price and I drove to his home. The guy is obviously an experience diver and a tech. diver as well. We start talking and I tell him I dive with a steel tank and a wetsuit. As soon as I tell him that, he starts telling me how dangerous it is, that I am a fool, that he would never dive with someone like me... well you get the point it actually started to get really awkward...
The reason he says that diving with a (single) steel tank is dangerous it that if your BC fails, the negative buoyancy of the steel tank would make it impossible to go back up on a deep dive. I then told him that I could use a safety sausage or a lift bag to lift me back up should my BC fail, then he said if that failed too I wouldn't be able to go back up. He then went on saying that you should only dive with a steel tank if using a drysuit. And added again how much of a fool I was

Is there any truth to that? Is it that dangerous to dive steel with a wetsuit? All the UICC instructors dive wetsuit and steel, actually most instructors or experience divers I ever see diving have steel tanks. Can so many people be wrong?

Why did you ask this question in the DIR forum? Don't you think that is asking for a beating?

If you are wearing a thick wetsuit, which is not a good idea anyhow, then you need to be conscious of your contingencies. Yes, wings & B/Cs fail.

An aluminum tank is a nice elevator at the end of a dive. To compensate for it, you must normally put 6 lbs of weight on your belt, or wear a steel backplate, to neutralize it. The belt is ditchable, whereas the backplate is not (since it stays attached to the tank under most circumstances).

A steel tank can be anywhere from several pounds negative, even when empty, to neutral, depending on the tank.

The air in your tank weighs as much as 6 lbs as well (0.08 lbs per cu ft). But as long as you can stay calm, you can breathe this down, as you head, or crawl, back to shore, were you to lose the function of your wing or B/C, and you did not have a backup buoyancy device.

The issue you need to face is regarding the backup buoyancy device. For most cold water divers (north-west Pacific) this means their drysuit.

You could also opt to put 2 independent wings on your backplate, making one available as a backup for the other. This solution is fairly uncommon these days, but it is available.

I do not consider a lift bag as a viable backup. It is easy to fowl up the deployment of a lift bag. Plus you need to be stopped, such as on a reef, or the sea floor, to have time to deploy it, once you have lost your wing or B/C function. If you are going down, it won't stop your uncontrolled descent. So forget about the lift bag idea. It is a red herring.

The issue becomes whether you can swim-up your steel tank about 30 to 60 ft until your wetsuit becomes buoyant again, even with dropping your entire weight belt, after you have lost the function of your wing or B/C?

Since you cannot try this, without risking an embolism or DCS, there is no way you will ever find out, until it is too late. (Nobody would recommend trying an EBA from deeper than about 15 ft, these days.)

That is why most expert divers recommend against a thick wetsuit in cold waters together with a steel tank. Better either to get a drysuit, or else to stick with an aluminum tank, and all your weight on your weight belt, or in ditchable weight pouches with an integrated B/C.

If you have access to a good instructor, he/she can go out into the open water with you, and you can dive together to 100 fsw, and then while you are both kneeling on the bottom, you could take off your weight belt and hand it to him/her. You will be surprised that you do not need it anymore at 100 fsw, since your wetsuit has compressed to virtually -0- buoyancy, and with a steel tank. Don't try this alone however.

 

[jefffalcone]

What I have heard is that a 7 mil wetsuit could have as much as 23 lbs of positive buoyancy, of which it will lose almost all at 100 fsw. If you are using aluminum tanks, they are positive when empty, which means you're carrying weight to sink the empty tanks. If you're diving steels, you're letting the negative buoyancy of the empty steel tanks contribute to sinking your wetsuit. That's weight you can't ditch. The weight you are carrying to sink your aluminum tanks IS weight you can ditch, assuming you have it somewhere you can ditch it. So it will be much easier to get back to the surface in the event of a wing failure at the beginning of the dive, if you are diving aluminum tanks.

Frankly, if you're diving that deep, a redundant buoyancy source (i.e. dry suit) seems like a good idea to me.

I dive with 8 lbs of lead with my hp100 which is -2.5 lbs when empty wearing a 7ml. That only makes 10.5 and that includes the bouyancy that is inherent in my body. Of course I wear a small wetsuit. I guess a xxxl could be 23 lbs positive. I don't disagree that redundancy is always a good idea, but people routinely dive to 100 fsw with steel tanks wearing wetsuits. It is definately possible to surface safely with a failure of your BC and without a rudundant bouyancy source.

Besides, if you are weighted properly, you are only using 3 lbs of tank weight to offset the bouyancy of your wetsuit. The rest of the 23 lbs you refered to will have to be lead (assuming you are using a traditional BC, not a BP/W). You will also have 5 or 6 lbs of lead to offset the weight of the air you are planning on breathing. That leaves 26 lbs of ditchable weight. Hypothetically, let's assume that your wetsuit is neutrally bouyant at 100 fsw. This would leave you 3 lbs negative if you had a BC failure with a full tank and 3 lbs positive if your tank was low (I know your tank shouldn't get this low, just for the sake of arguement). Either way you shouldn't have a problem surfacing. If you can't swim up 3 lbs negative you probably aren't physically fit enough to dive. Only difference with aluminum is when you ditch your weights, you will be about neutral with a full tank and about 6 lbs possitive with an empty tank. When you think about it, the aluminum is probably more dangerous if you ditch you weights because that extra bouyancy will make it harder to have a controlled ascent once that 23 lbs of bouyancy kicks in.

 

[nereas]

I don't dive a farmer john, but with a fully compressed 7ml onepiece properly weighted using a HP100, I am able to stop my descent just by taking a very deep breath. I estimated this to be about 5 lds. I guess my lungs could provide more lift than that. If you really want to be sure swim up with 10 lbs of lead. Either way I think you'll convince yourself that it can be done.

Yah, how hard could that be, swimming up "only" 10 lbs of lead??

Ever tried it yourself?

 

[nereas]

... people routinely dive to 100 fsw with steel tanks wearing wetsuits. It is definately possible to surface safely with a failure of your BC and without a rudundant bouyancy source.

...

People routinely drive DUI in traffic as well. And not all of them cause fatal car crashes either.

Probably only the unlucky ones do, huh??

 

[jefffalcone]

Nereas,
If your contention is that diving to 100 fsw in a wetsuit is dangerous, I will not argue with you, but the idea that it is somehow more dangerious with a steel tank than an aluminum tank doesn't make any sense to me. The difference between a steel tank and a aluminum is only about 5 or 6 lbs depending on the tanks. I have picked up a 5 lb weight and swam up from about 20 feet. It wasn't even slightly hard. I'm sure I could have gone another 40 feet w/o any trouble. To answer your other question, I haven't tried 10, but I believe I could do it. If you actually did ditch your weight, as I pointed out in the post you quoted, I think it would be a little safer to have a steel tank, because the extra weight would help you control your ascent once you did become bouyant.
Do DIR people really think that it is dangerous to dive with a steel tank and a wetsuit. If you think wetsuits are just dangerous, I can't really argue with that, but I haven't heard any reasonable evidence why aluminum is safer that steel.