Does extreme cold water diving call for fully redundant regulators?

[Divin'Papaw]

For me it does. I've moved exclusively to doubles with an isolation manifold when diving in cold water. I see that setup alot on Great Lakes wreck diving charters, even amongst those diving recreational depths/bottom times.

 

[Thalassamania]

Id suggest all divers should have an a redundant air source adequate to get them to the surface on EVERY dive.

Shall we take this hijack to: Should all divers have a redundant air source on every dive?

 

[AndyNZ]

Being blessed with temperate water all year round, I don't feel overly qualified to comment in anything other than the most general terms.

It would certainly seem prudent, Thal. But whether it's strictly neccessary, I don't know.

 

[beester]

In our waters summer and winter the standard is:

15 L steel tank (I don't know the tank in us measurements.. is it a HP 100 or 110?)

H or Y double valve

Fully redundant regulators (so 2 1st stages 2 2nd stages)

This or doubles (mostly 10L's or 12L's)

The air-users are also split between 1st stages. So primary reg and drysuit inflater on primary 1st stage. Backup reg and BCD or wing inflator on secondary 1st stage.

The Y or H valve on a single tank is not meant to do on your own valve-shutdowns... because it's very hard to reach the valves without getting out your bcd or pushing it up after loosening the webbing. If you want to be able to do that you need a double with isolator valve. But with a Y or H valve you do split the gas demand between regulators (so minimizing freeflows) and in case of a deep freeflow your buddy can shutdown your main valve while you go to your backup reg (so freeflow doesn't mean you lose all your gas). Normally with 3 m³ (106 cubic feet) of gas you have enough time to shut down a valve.

Cheers

 

[Doc Harry]

I went diving in the Great Lakes last summer (water temps 40-50s degrees F). Almost everyone on the dive boat had pony bottles. I commented that I'd never seen so many people with pony bottles. They informed me that the cold water causes so many regulator free-flows that they all carry redundant cylinders and regulators.

 

[Buoyant1]

After the Gilboa (I think) incident last summer or the summer before, I was considering an "H" valve, but got talked into a pony by a dive buddy (not a shop employee). The scenario tossed to me was if your primary second stage starts to free flow, do you know that it's the reg or that it's the first stage? In that case the shut down of the primary and going to the secondary won't work. So I got the pony bottle.

It's not a problem diving with it either, it's actually pretty easy!

 

[JeffG]

Given the increased probability of a regulator failure in very cold water and the fact that ice may complicate your ascent and the reality that having two divers breathing off a single first state will greatly increase the likelihood of free flow ... would it be prudent to dive with a fully redundant regulator, (e.g., isolated doubles, independent doubles, pony, etc.)?

When I used to ice dive, (haven't done it for a couple of winters) we used to require a redundant air supply. So it was either doubles or a pony (rigged like a stage).

 

[Hawkwood]

When I ice dive it's been at least one redundant supply per two person buddy team. I sling a 40cuft pony.

 

[NudeDiver]

Given the increased probability of a regulator failure in very cold water and the fact that ice may complicate your ascent and the reality that having two divers breathing off a single first state will greatly increase the likelihood of free flow ... would it be prudent to dive with a fully redundant regulator, (e.g., isolated doubles, independent doubles, pony, etc.)?

I don't see how it could have any significant disadvantages - certainly not enough to outweigh the advantages.

 

[don Francisco]

With increased risk of failure, prudence calls for increased redundancy.

Unless you're limting depth to a floor shallow enough that a direct bailout to the surface is a reasonable solution to an air supply failure, intelligent risk management mandates a redundant air supply. Sharing air in cold water at depth too quickly becomes a race against time.