Steel tanks dangerous?

[Soloist]

The sky is falling, the sky is falling! Steel tanks are NOT dangerous. Executing a dive without understanding your weighting, dive plan, buoyancy and physical capabilities most certainly is. When diving my steel tanks I am extremely negative with no ditichable weight and I can swim my rig to the surface at the beginning of a dive with an empty wing. Furthermore, I do not have a death wish. If you are unable to swim yourself to the surface diving a single tank there is a problem.

 

[rsingler]

You keep saying steel tank why is a steel different to an aluminium?

You are correct. Your post above points out that when properly weighted, both tanks end up with the same net buoyancy: steel plus a little lead, or Al plus more lead.
I think the OP is pointing out that with a steel tank, you have less flexibility in ditchable weight. That might make Aluminum a better choice for partial weight ditching. But the issue of partial weight ditching is a controversial topic probably outside the Basic Forum.

 

[Compressor]

I have been told to consider dry suits when diving steel tanks. I have bee diving them for years - in both wet and drysuit. But never really see if that is true. Several hundred dives later, I have not died yet! That is a YET. So I descended to 80 ft today with 120 HP single steel. 4 lbs ditchable weight, and 2 none. No backplates. Tried to fin up, but barely able to maintain more than 1 minute when the BC is empty. I had a small pony too, which is like another 2 lbs. I tried the lift bag. It worked, but not well. The dump valve is high, but lacking good control as a lot of air has to be added before you can dump. So the large lift bag as a redundant BC is not ideal. Suggestions to make diving safer with steel tanks? Thicker wetsuits? Better brand lift bags? Always dive where there is a safe hard bottom? Please do not say drysuit??

Have you done a buoyancy check with the equipment you were wearing? 500 psi end of dive and BCD empty see if you need any weight at all.

 

[Compressor]

FYI for beginners: Steel tanks are NOT dangerous. (The original OP put a ? after dangerous meaning it as a question.) In fact they are favored among many divers including experienced ones. A good buoyancy check is needed every time one dives with a particular new set of equipment and then logged in logbook. THEN when that set is used for diving, one looks at their logbook to see how much weight they need.

While extra work and thought is required, it makes the dive more enjoyable by allowing diving to occur with less air consumption, better buoyancy control and so on so forth.

 

[fisherdvm]

Have you done a buoyancy check with the equipment you were wearing? 500 psi end of dive and BCD empty see if you need any weight at all.

As I mentioned.... at 500 psi I have problem holding a 15 ft safety stop with 3 lbs lead. That is why I carry 5 lbs lead. I have been diving same set up for over 50 dives. Great for lobstering - as you have plenty of air to chase them down. I just did not realize how difficult it is to fin that pony, plus 5 lbs lead, plus the 11 lbs of compressed air. At the end of the dive, it would be only 2 lbs of air. Shedding 9 lbs. I should be able to kick up at the end of the dive easier.

 

[fisherdvm]

As some one suggested, shedding the pony, shedding the 4 lbs, etc. Safest thing to do is send up my 6 ft SMB on a line, and winch myself up. I tried testing the lift bag method that DoctorMike said he did in training, at least with the generic lift bag I had - it was not very precise. Using it on a line is safer than in the hand or on the BC.

 

[BRT]

You keep saying steel tank why is a steel different to an aluminium?

Steel tanks usually are less buoyant than aluminum tanks. I. E. you have to wear more lead to sink aluminum tanks so you have more lead to ditch in an emergency. This only matters to people who are not highly buoyant, like me.

 

[BRT]

As I mentioned.... at 500 psi I have problem holding a 15 ft safety stop with 3 lbs lead. That is why I carry 5 lbs lead. I have been diving same set up for over 50 dives. Great for lobstering - as you have plenty of air to chase them down. I just did not realize how difficult it is to fin that pony, plus 5 lbs lead, plus the 11 lbs of compressed air. At the end of the dive, it would be only 2 lbs of air. Shedding 9 lbs. I should be able to kick up at the end of the dive easier.

So as you go through your air trying to swim your negative setup to the surface the problem is self solving.

 

[boulderjohn]

Let's say you are using a tank with -7 pounds of buoyancy when it is full. Let's say need to carry 4 pounds of weight in order to handle a safety stop. Let's just look at what that means.

Buoyancy is determined by tour total diving package--you, your tanks, your BCD, your other gear, and your weights, not just the weight of the tanks and the lead you carry. If you are neutrally buoyant at the end of the dive, then your total dive package weighs the same as the water you are displacing. Take those weights away, and you head for the surface. At the beginning of the dive, that same size package will be heavier, but only by the weight of the gas you will lose during the dive.

Therefore, if you are properly weighted during a recreational dive and don't ditch any weight, the only weight you have to be able to swim up at the worst point in the dive is equal to the weight of the gas in the tank. That is true of all tanks, steel or aluminum. If you are carrying ditchable weight as part of your total package, the only weight you would have to swim up would be equal to the weight of the gas in the tank minus the weight of the lead you ditch.

A steel 120 holds 9 pounds of gas. If you are properly weighted and carrying 4 pounds of lead, then in the worst case scenario you will need to swim up 5 pounds of excess weight.

 

[Steve_C]

Assuming you are over a hard bottom with a pony you do not have to swim up a full tank at the start of the dive. You could always dump some air. Not recommending it, just pointing out that swimming up a full tank is usually a choice.

Wearing a dry suit does not cure all problems. If dry suit floods, you are out one source of buoyancy.