Diving with a 15 litre tank.

[Frosty]

For normal scuba it seems to be normal to dive with 11.5litre ally tanks or 12.0 Litre steels.
For boat diving I'm wondering why a diver wouldn't dive with a 15 litre tank.
Wouldn't that offer a lot of the advantages of a pony bottle?

 

[skyguy94]

In many places you can. The last place I did it was in the Red Sea. However, while it gave me longer bottom times while using Nitrox, my gf used a 12L and we had to take that into account in our gas planning. A pony provides redundancy, where just adding a larger tank does not.

 

[scubadiver888]

For normal scuba it seems to be normal to dive with 11.5litre ally tanks or 12.0 Litre steels.
For boat diving I'm wondering why a diver wouldn't dive with a 15 litre tank.
Wouldn't that offer a lot of the advantages of a pony bottle?

It would offer more air but a pony bottle has a second set of regulators. Having more air isn't very helpful if (a) your gauge fails and you breath the tank down to zero, (b) have a free flow on the regulator, (c) have a failure on the system. Additionally, the 15 litre steels are typically longer than an 11.5 litre aluminium and a lot longer than a 12.0 litre steel. This might be a buoyancy/trim issue for a lot of people.

 

[AndrewA]

I like diving with a 15 litre steel cylinder. It gives me a longer bottom time and lets me take a little lead off my belt. If I am diving deeper than 25m I usually carry a side slung ali 30 or 40 as an independent bail out. The 15 litre steels are the same height as normal12litre (and ali 80s) they are of a wider diameter. I don't notice any real difference in trim

 

[Ottoman Diver]

I have never had problem diving 15L it just feels like im carrying a dog carcass on my back on the surface but under water i have never had much of a problem The ones i have dove are a bit longer then the 12L tanks but i had no problem with it

 

[DaleC]

What kind of dog?

 

[cloudflint]

I like diving a 15 litre from a boat since i can just slip it on and fall in the water, always nice to have the extra gas. For shore diving i find it can be quite a chore at times particually if i have to do any climbing to get in and out.

 

[rameus]

for boat diving there are a lot of people using 15l tanks. i just got the experience that when you keep yourself in shape and do a bit of cardio-training you'll need less air (at least this is the case with me). don't know how that works with others but i try doing it this way since i make sure that i stay in shape ;-)

Thomas

 

[supergaijin]

15 L definitely gives you more gas but at at a cost of extra weight at the surface and a difference in balance and hydro-dynamics underwater. For given conditions I will dive with a 15 but generally they are for longer deeper dives.

Many DCs will put an extra $5 or so on to the price of a 15. They're also right bastards for the crew to load. Steels are even worse!

 

[Ottoman Diver]

What kind of dog?

A German shepherd