Steel tank as pony bottle for Self Reliant Diver.

[Biczmusic]

Hello everyone.
Hope you had amazing New Year's Eve and looking forward to diving in 2024.

I've been reading many post here about an extra tank for solo diving, but all of them talk about alluminium tanks.
I have a question about a steel tank so I thought I star a new thread.

I am thinking of purchasing a second tank for my Self Reliant Cert and solo dives that will follow.
I have 2 tanks to chose from and would like to ask for your opinion/experience...
1. Steel 10l tank
2. Steel 7l tank

Now, the 10l is very attractive for me as I could use it for the dives with other, less experience divers, where I use less air on a shallow dive - as well as as pony bottle for my solo dives. The disadvantage I see is the size - I'm worried it will be cumbersome to have it swung one the side.
The 7l feels like it will be much more streamline to have it on the side, but it will be too small to use as a main tank for shallow dives with others, and I'm also wondering if 7l is enough for a pony from a deep-ish solo dives (30m-40m).

I'm definitely going for steel as I prefer it's buoyancy profile, but the size and comfort are somethings I would be keen to find your opinion about?

Thanks in advance.

Marcin

 

[Bowers]

A pony bottle is generally attached asymmetrically and therefore if it has much negative buoyancy it sucks. Aluminum tanks are generally closer to neutral (al40 is a dream to carry). How do you plan to carry your pony?

 

[Bowers]

Also, not to derail the subject, but have you considered sidemount? Sidemount diving is awesome for solo diving and has lots of perks.

 

[Biczmusic]

A pony bottle is generally attached asymmetrically and therefore if it has much negative buoyancy it sucks. Aluminum tanks are generally closer to neutral (al40 is a dream to carry). How do you plan to carry your pony?

I was going to clip it to my bcd on the side, like you would with a stage tank, at least that was the idea.

 

[MidOH]

Then al40 is what you want. Modular left valve. Shouldn't throw off your trim much.

Smaller bottles are too negative in the water. And 40 gives you more options. Makes a nice stage or shallow bottle later.

Thunderbird AL-40 Cylinder, Brushed No-Coat

Experienced divers prefer the trim characteristics of the aluminum 40 size cylinder for deco, bailout and sidemount applications.

www.divegearexpress.com

One on each side, and you effectively have a decent beginner tec rig.

 

[Bowers]

I was going to clip it to my bcd on the side, like you would with a stage tank, at least that was the idea.

This is my preferred way for ponies and I personally don’t like a tank on my side that’s more than about 3 lbs negative buoyancy

 

[Angelo Farina]

I had a 7l steel and it was terrible.
I almost instantly replaced it with a 3 liters aluminium, which is more compact and perfectly neutral, while still providing almost 600 liters of air, which are plenty enough for a controlled ascent from 40m, including a safety stop.

 

[MidOH]

An Al72 seems to have the same buoyancy as a Al40. But have never tried one.

 

[MB NZ]

Personally, I think either of those cylinders would be horrible in terms of balance (I've used a side slung steel 10L). That said, anything can be made to work depending on what you're willing to put up with. My vote would be an aluminium 3L or AL40 depending on gas requirements.

 

[Gandalf-the-Diver]

Hi .... ali is what you need. The steel tanks, yes have better buoyancy characteristics, however, if you are switching to your pony, you are on your way up anyway and buoyancy is not an issue. My 1st pony, was a 13cu Ali Catalina tank, which was great for shallow, and being only OW at the time, not an issue. Luxer and Catalina tanks have different buoyancy characteristics, with Catalina being better neg buoyancy. I went with a 30cu for my pony since my AOW, again, a Catalina tank due to better buoyancy. I preferred the 30 over the 40, due to smaller physical size, and again, better buoyancy. The steel are just too heavy to use as a pony, and if slung, you will need to counterbalance them with trim weight. (I looked at steel too, when I 1st wanted a pony bottle, aluminum however, won out)