Steel doubles in the tropics

[LeadTurn_SD]

I would guess that even the most hardened supporters of the "no steel doubles w/wetsuit" mantra would make an exception for LP72s, as they are far less negative than the majority of steel tanks.

Another vote for steel 72's and 3mm wetsuit.

I'm still diving my original steel 72 that I bought in 1976. The last time I needed to have it hydro'ed, the local dive shop owner asked if I wanted to sell it.. I politely declined

As soon as I find another steel 72, I plan to double it. They are great tanks.

Best wishes.

 

[Ed Palma]

I had a chance to buy steel doubles but bottled it after reading various threads on SB and assembled a set of aluminum doubles instead (at greater expense).

Hi Rhone Man,

Could you provide a link to some of these threads? I'd like to take a closer look at them. Thanks.

 

[Rhone Man]

Hi Rhone Man,

Could you provide a link to some of these threads? I'd like to take a closer look at them. Thanks.

I had a dig around, but I cannot relocate the thread now (I went through my last 500 posts and it wasn't in there, so it must have been a while back).

The definite gist of the advice being posted on it was that steel doubles in a wetsuit was a risk because of the lack of redunant bouyancy. I don't remember any serious dissenters.

 

[iztok]

I had a dig around, but I cannot relocate the thread now (I went through my last 500 posts and it wasn't in there, so it must have been a while back).

The definite gist of the advice being posted on it was that steel doubles in a wetsuit was a risk because of the lack of redunant bouyancy. I don't remember any serious dissenters.

I think that the core of the idea is that you can only swim up so much negative weight on your own. Past that you need some buoyancy control device to help you. If that device fails you need to have backup or ability to ditch some equipment. If you don't have those then you are not properly equipped.

With steel (other than 72cf I guess) you need redundant buoyancy device and drysuit can offer one. Double bladder wing could also be an option and some argue that SMB/lift bag can do the same.

 

[LeadTurn_SD]

Doc Ed,

It comes down to how much buoyancy your wetsuit can lose at depth versus how heavy your tanks and other non-ditchable ballast is.

When I started diving with my steel 72, I did not use a BC. Neither did anyone I was diving with here in Hawaii in those days. BC's were not yet in common use.

So, every single dive, we swam our steel 72's up from depth.... sometimes from VERY deep. They are simple not very negative, even when full.

You do need to consider how much lift your current wetsuit provides (it will lose most, but not all, at depth), how much personal buoyancy you have (this does not change with depth), and overall how negative your "rig" is.

Larger heavy steel doubles combined with thick wetsuits (7mm) present the problem.

The wetsuit provides a lot of lift at the surface, but loses this with depth, and the BC compensates for the loss..... but lose the BC, and you could find yourself over 20lbs negative, or more, at depth. Thus the recommendation to use drysuits with heavy steel doubles, not wetsuits.

Best wishes.

 

[boulderjohn]

It comes down to how much buoyancy your wetsuit can lose at depth versus how heavy your tanks and other non-ditchable ballast is.
...

Larger heavy steel doubles combined with thick wetsuits (7mm) present the problem.

Nice summary.

If you are talking about 3 mm suits and smaller steel tanks, you really should not have too much trouble.

I have never dived steel doubles of any size with a wet suit, but I have dived single steel 112s and single steel 120s with a 3 mm suit and a BCD quite a few times. In both cases, I was pretty close to properly weighted, so I was diving with little or no air in the BCD--the equivalent of a wing failure. I had no trouble at all with that kind of weight, and I really don't think I would had a lot more trouble with a second tank.

But that's me.

 

[TSandM]

I think the reason the technical threads on steel doubles and a wetsuit are pretty unanimous that it's a bad idea is that very few people do technical dives on doubled 72s. They really don't hold enough gas, and since they are mostly older tanks, you can't really cave fill them, either.

They make really nice doubles for doing a couple of deeper recreational dives in a day, but even I found that I had to cut the second one short to maintain reserves.

Most of the steel tanks that are used for cave or technical diving are much more negative and rapidly exceed what's safe to dive without redundant buoyancy.

 

[knowone]

Vintage purists need only apply. Physical characteristics should be identical to avoid parallelogramism. Manifolds and bands orig that fit without stupiding around are a dime a dozen. May become slightly thermally challenged. Frozen nuts is my only cave wetsuit issue. Your wing will be fine. They are there. Buy them. No Tech for you.

 

[Ed Palma]

Here's a phonecam shot of one of the tanks I'm getting.

The seller sent in a whole bunch of other photos, and from them I can ascertain that the last hydro was prolly in '84. They still look good externally, and they've been stored with air. According to him, they were last dived 4 years ago.

These are some of the photos of the shoulder:

At least he's throwing in the backpack and harness for free...

I am unfamiliar with this type of valve. Can anyone supply more info on them?

 

[Ed Palma]

Vintage purists need only apply. Physical characteristics should be identical to avoid parallelogramism. Manifolds and bands orig that fit without stupiding around are a dime a dozen. May become slightly thermally challenged. Frozen nuts is my only cave wetsuit issue. Your wing will be fine. They are there. Buy them. No Tech for you.

Love your posts...

You wouldn't perchance, work for the companies that write instruction manuals, would you?