Tank redundency

[oversea]

I had come accross an older Poseidon 1st & 2nd stage on a job site a few weeks back. Contrary to my beliefs, my LDS said they were pretty good and could use them. As I have been considering starting out with a pony bottle (in add. to my 80's) I though these regs would be good for this application. My first question is a size recommendation for a pony bottle? I was considering a 13 or 19. My next is about doubles. I am not sure I will ever need them but, if I were to get doubles, would I ditch the pony? I could understand keeping it for a deco mix, but are there any other reasons to keep it? And finally, using doubles, would I want to have two regs (two first stages and two second stages) with an isolation bar or just one complete reg? How about keeping the pony, using doubles and only one reg combo on the doubles.

 

[oversea]

The reason I am asking the above is because I have never really done much boat diving up here in the northeast and from what I understand, most boats are looking for some sort of redundency for you to go out with them. If someone knows different, please correct me.

 

[matt_unique]

I had come accross an older Poseidon 1st & 2nd stage on a job site a few weeks back. Contrary to my beliefs, my LDS said they were pretty good and could use them. As I have been considering starting out with a pony bottle (in add. to my 80's) I though these regs would be good for this application. My first question is a size recommendation for a pony bottle? I was considering a 13 or 19. My next is about doubles. I am not sure I will ever need them but, if I were to get doubles, would I ditch the pony? I could understand keeping it for a deco mix, but are there any other reasons to keep it? And finally, using doubles, would I want to have two regs (two first stages and two second stages) with an isolation bar or just one complete reg? How about keeping the pony, using doubles and only one reg combo on the doubles.

Pony size depends upon depth. Shore dive down to a max of 75' a 13CF pony is fine. Deeper dives down to say 100' go with a 19. Down to 130' I would opt for a 30CF min. You can use these bottles later for stage bottle/deco purposes. If I were buying equipment anew I would go for the largest pony I can manage in terms of weight/traverse for shore dives/etc. because you would want a min of 30CF later on for deco bottle purposes.

You would want a reg on each "post" of your setup. So for doubles with a deco bottle you have 3 totally seperate regs (3 first stages, 3 second stages, etc.) You should do this with or without traditional manifolded doubles. (Meaning you would not want to have manifolded doubles with isolator with only one regulator on the system).

Most charter boats will require a pony bottle for deeper wrecks (100-130') and a min of Advanced Open Water certification.

--Matt

 

[pescador775]

One thing to count on is that everybody in the dive business has rules of some kind, to protect themselves from liability or to push more sales. Many head boats require various types of redundancy, especially for 'buddy breathing'.

It's a shame that the tank mfgrs don't still produce slender bottles with low drag which would be suitable for doubles. This would provide a convenient way to carry redundant air for those who don't do deco dives or do minimal deco. Some folks use double 45's but I don't favor this because connecting hardware is not readily available for rigging up a compact, close set arrangement, and the total air capacity is rather minimal compared to the cost of filling the things. Depending on your air needs my recommendation is to go with doubles, maybe double 72's. These can be had rather cheaply. Install the isolation manifold and twin regs. The tube type second stage with a slightly elongated hose , for example a Poseiden, would be a good secondary. Forget the pony, those things are really only suitable as bail out bottles for hard hat divers.

The reason I am asking the above is because I have never really done much boat diving up here in the northeast and from what I understand, most boats are looking for some sort of redundency for you to go out with them. If someone knows different, please correct me.