pony bottles

[docmojo]

I have not heard of the Mojo blues band. I will look them up on the net. I am a big fan of the blues.. as well as playing southern rock, blues and 60/70 rock...
Thanks for your input...

 

[AndyNZ]

Do a search on "rock bottom" on how to calculate gas usage etc.

When I did the calcs, I decided on a 3 litre (~19cu ft) pony which is just about enough air to fanny about for a minute at 30m, ascend at a normal rate and do a 3 minute safety stop. But it's cutting it fine....

I'd second the suggestions to sling it rather than mount on the tank, I keep the reg bungied to the pony so it doesn't clutter my chest area - particularly relevant if you are diving with a pony *AND* and alternate second stage.

 

[dkktsunami]

I have not heard of the Mojo blues band. I will look them up on the net. I am a big fan of the blues.. as well as playing southern rock, blues and 60/70 rock...
Thanks for your input...

Mojo, Google "Ripete Records". Album you want is "Take A Train". Even though they are sorta geeky white guys, this is southern black blues at its best. Great scuba music for surface interval.

 

[my1ocean]

Just my point of view.

I tend to agree with the advice 2Tours got. If you are recreational diving, I think it's more hastle than it's worth. By that I mean fills, hydros, space you take up on a boat, lugging the extra tank... One really can't argue with redundancy. It's always good to have redundancy, but in some cases, is it necesary? O-ring blow outs are not that common (never had one in over 1200 dives), and as it happened with Docmojo, that's what your buddy is there for. One other point on that. It takes some time for a full tank to drain and as a tank empties during a dive, the less likely you are to have an extruded O-ring.

As for regulator redundancy, you could use an H valve on a scuba cylinder. Again, is it necesary for recreational diving with well serviced gear?

 

[mnj1233]

Just my point of view.

I tend to agree with the advice 2Tours got. If you are recreational diving, I think it's more hastle than it's worth. By that I mean fills, hydros, space you take up on a boat, lugging the extra tank... One really can't argue with redundancy. It's always good to have redundancy, but in some cases, is it necesary? O-ring blow outs are not that common (never had one in over 1200 dives), and as it happened with Docmojo, that's what your buddy is there for. One other point on that. It takes some time for a full tank to drain and as a tank empties during a dive, the less likely you are to have an extruded O-ring.

As for regulator redundancy, you could use an H valve on a scuba cylinder. Again, is it necesary for recreational diving with well serviced gear?

Thats not what my buddy is there for!!!! Cold water, two breathing thru the same first stage, not a good idea!!!!

 

[my1ocean]

Thats not what my buddy is there for!!!! Cold water, two breathing thru the same first stage, not a good idea!!!!

As with all diving, one must take into account the type of diving you're planning on.

Thanks for clarifying.

 

[lostplanetairman]

When I dive off Jersey its required if you're diving single tanks. A 30 is minimum IMO and is best slung. Plus, down the road it'll make a nice deco bottle. :scubadive

 

[Sea-Diver]

There are two tanks that have been released this year that fit the requirement.

One is an aluminum 20 that only weighs 10lbs and is only slightly larger than a 13 cu ft

The other is a steel 30 that is the roughly the same size as the 20 and weighs in at 15 lbs.

The inwater characteristics are:

Alum 20 5lbs negative full to neutral

Steel 30 7lbs negative to 4lbs negative

 

[Don Burke]

The inwater characteristics are:

Alum 20 5lbs negative full to neutral

Steel 30 7lbs negative to 4lbs negative

Does this mean that 20 SCF of air in an aluminum cylinder weighs more than 30 SCF of air in a steel cylinder? I suspect not.

Cylinder buoyancy charts are notoriously inaccurate. My guess is that someone screwed up on the computations for the aluminum 20.

 

[String]

I thought about getting a pony bottle but was talked out of it by mu scuba instructor (I had private lessons) because it only gives you a false sense of security. Proper gas management and constantly checking your guages will prevent you from running out of air.

I really dislike people spouting things like he said without thinking it through.

Plan for worse case scenario. Theres a current, vis is low, you get buddy separated say 35 mins into a dive.

You do the usual swim around for 60 secs before commencing an ascent. Suddenly, bang first stage freezes resulting in second stage freeflow. You've been down long so dont have much air left in the tank. It empties in 30 seconds. You now have no air source, no buddy and an ascent to do. A pony would enable to do that. Without one youre looking at probably injury or worse.

A redundant air source is NOT an excuse for poor gas managment but provided its used as intended (NOT as a main gas source but as an emergency) and the dives performed arent too silly/deep for it its a good get out of jail free card.