Solo diving and back up gear.

[John C. Ratliff]

An H-valve provides excellent redundancy with simplicity and minimal gear and thus minimal diver stress due to gear handling in an emergency.

I counted up the number of O-rings that need to be maintained on two different regulators I would put on two tanks (eithe H-valve or independent doubles). That count was 18 different O-rings. Each O-ring is a weak point in the system; they need to be maintained to work.

If you will compare this diving rig with the original Cousteau triple tank rig, you will see that Cousteau's divers dove with no O-rings. Their entire scuba had six moving parts (excluding valves, which added about three each). They dove a system that kept the entire contents of one of the cylinders as their reserve (activated by a hand valve at the bottom of the scuba).

Cousteau's original system kept diving equipment simple. The independent doubles and H-valve are not simple devices, and complicate the diving, need much more maintenance, and more practice to ensure you know where everything is.

SeaRat

 

[JS1scuba]

A small "pony" is useless. 19 cu ft is the minimum in my opinion for non-deco deep diving. 30 cu ft is the minimum useful size for deco diving as anything less will not get you or your OOA buddy to the surface on a moderate deco dive.

I have a feeling that your use of the word "useless" is not on target with what you really mean.

For decades the north east / great lakes wreck diver used single tanks and a "pony" for conducting dives and having a "little extra" in case they needed it. When I first started diving solo in 1989 I had a single and a pony. It was clear that the purpose of the pony was not to extend the dive but to provide that additional amount of air should it be needed to ascend.

Since this discussion is about Solo the OOA buddy argument needs to be removed.

The stock 13 / 14 / 19 cuft pony provides sufficient gas to ascend from 100 fsw and then do a decent saftey stop. It's not for horizonal swimming while at depth.

The other use for the pony while solo is it provides an excellent tool to inflate dry suit / BC expecialy in cold water, thereby helping to minimize the possiblty of a regulator freeze up/ free flow.

When properly set up the Pony works well on a single tank and does not take up much room. If one is conducting external wreck diving or standard open water diving its pretty compact.

My nickel's worth....

regards,

 

[Rick_G]

Hello-

I think the confusion could be cleared up by calling them independent doubles. One tank >=80cf and one tank >=13cf depending on profile. So when people ask if that's a pony, say nope! I dive doubles It avoids all the name calling.

Rick

 

[Scuba]

No secondary or backup air system is useless underwater when properly used within its safe operating parameters. When properly used, a back-up is adequate for a proper and safe abort when the primary system fails. But they are all limited. Yet, in all cases, it provides a greater safety margin than aborting the dive with a malfunctioning or depleted air system.

 

[Nemrod]

To confuse things, I like the doubles suggestion. When I will dive vintage with my beautiful Mistral double hose regualtor I will run a second bottle with another lovely oldie, an equally ancient Calypso single hose. This regulator has been in continuous use for 38 years and has never failed so it is an adequate backup. I figure for this purpose a 13 to 20 cf double bottle will be fine. If the Mistral quits on me which is far less likely than my being hit by a comet I can switch over in a flash to the Calypso which has a failure rate equal to the likelyhood of the sun going into supernova and at that point I will just abort the dive. You only got a few minutes within deco limits at depths below 100 feet anyways. I certainly think it prudent whenever diving below 80/100 feet to sling a "decompression" bottle on the anchor line etc if possible--just in case of a problem. That will be my ancient Voit MR12 which also has a reliablity factor equal to the near certainty that the sun will rise again in the morning. In the event of a supernova the sun will not probably rise in the morning and in which case I am likely --well-- screwed. N

 

[msandler]

stowing a deco bottle on an anchor line would be unwise unless you are as sure as a "rising sun" you will not need it.

 

[DA Aquamaster]

Yep, if you think you may need it, it needs to be with you.

 

[Nemrod]

You guys are into carrying bottles and more bottles and then an extra or two. I am into having what I need to complete the dive within the 1/3 rule and in that case an extra bottle on the anchor line, assuming I am on my boat is certainly better than having it in the bilge. If it is a beach dive or a kayak dive or something else like that then another plan will be required obviously including carrying it around with you.

"Yep, if you think you may need it, it needs to be with you."

I think we are parsing the language. The reason it is there (on the anchor) is because I don't think I will need it since I am on a no deco profile! We can differ without causing a fuss, that is why it is a free country and I freely exercise that right. N

 

[gcbryan]

Obviously Mike has an overinflated opinion of himself since he constantly refers to anyone who he disagrees with as a "poser". I think you are too caught up in your self image as a "tech diver" Mike. And as a football player for that matter Who cares.

 

[msandler]

Its always the posers who say this - go figure