Redundant air with a drysuit

[gcarter]

Soon to be a new drysuit owner, and one of the things I started wondering about was the use of redundant air with a drysuit. I have no plans of going to doubles, but do sometimes carry a 40CF for redundancy.

This may be a stupid question, but do people put an inflator hose on their redundant air for their drysuit since there is no oral inflator? I suspect not, but you never know.

 

[stuartv]

Among single tank divers, I don't think it's very common at all.

With doubles, you'd typically have a LPI hose coming from each post, one for the wing and one for the drysuit. In theory, you could disconnect either one and plug it into the other. Ini practice, that is not likely to be as simple and easy as it sounds. But, with each having its own independent air source, it's not likely to be needed, either.

CCR divers often have a BCD whip (i.e. a BCD/drysuit inflator hose) on the reg that is on their bailout bottle(s). I think many even use a BO bottle as their drysuit inflation bottle as a normal thing (vs a redundant/backup source).

I don't think there is anything at all wrong with it if you want to put a BCD whip on your pony bottle 1st stage, for "just in case". Just make sure you do a little practice with deploying your pony bottle reg after you do that. It's not hard to stow the hoses on the pony bottle and end up with them crossed over each other where it kind of comes out as a tangle when you deploy the reg from the pony bottle.

I think it's actually a good practice when diving with a pony bottle to go through your bubble check with your buddy at the start of every dive and also deploy your pony reg, switch to it for a couple of breaths, and then stow it away again before you really start the bottom portion of your dive.

- You will ensure that the pony is turned on.
- You will ensure that the reg is not tangled and is ready to be deployed and used on a moment's notice.
- You will ensure that the diaphragm in the pony 2nd stage reg is not torn or holed - something you probably won't be able to detect when taking test breaths on it above water.

 

[doctormike]

Soon to be a new drysuit owner, and one of the things I started wondering about was the use of redundant air with a drysuit. I have no plans of going to doubles, but do sometimes carry a 40CF for redundancy.

This may be a stupid question, but do people put an inflator hose on their redundant air for their drysuit since there is no oral inflator? I suspect not, but you never know.

In what scenario would you need to hook your dry suit up to your pony bottle?

Assuming that you are not doing dives in caves with the need to descend on the way to the exit, If you had a failure of your primary back gas supply and you had to deploy your alternate gas supply, you would be ascending. You don't need to add any gas to a dry suit on ascent, you need to vent it.

 

[gcarter]

In what scenario would you need to hook your dry suit up to your pony bottle?

Assuming that you are not doing dives in caves with the need to descend on the way to the exit, If you had a failure of your primary back gas supply and you had to deploy your alternate gas supply, you would be ascending. You don't need to add any gas to a dry suit on ascent, you need to vent it.

What scenario? No idea - that's why I said it might be a stupid question I don't know what I don't know about drysuit diving, and I am trying to start with as few assumptions as possible.

 

[Graeme Fraser]

I do have an lpi on my stages but I only attach it to my drysuit if I'm on Trimix. I'm not saying it's right but I'm too tight to buy a suit inflation cylinder.

It's also quite handy for shooting an SMB with lpi adapter.

As Doctormike said though, from a redundancy point of view I'm thumbing the dive in these circumstances and only venting.

 

[RainPilot]

Couple of scenarios:

You find your dives are gas critical and you want to minimise gas "wastage". A BC whip on your pony will allow you to save that gas ( more during your learning period on the drysuit ) by using a bit of the pony rather. Downside, it is using your pony (emergency) gas so you need to factor that in. The volume of gas we are talking about is pretty small all told.

In an actual pony ascent (total back gas loss) you will be able to inflate using your pony, you won't need to add on the ascent (venting only) but you can add gas once on the surface to assist in flotation if that's a concern.

Personally, I wouldn't use the pony for the suit, but I would add a suitably stowed whip to the pony in case it becomes necessary, and practice switching to it every so often to ensure all is well.

 

[KenGordon]

Soon to be a new drysuit owner, and one of the things I started wondering about was the use of redundant air with a drysuit. I have no plans of going to doubles, but do sometimes carry a 40CF for redundancy.

This may be a stupid question, but do people put an inflator hose on their redundant air for their drysuit since there is no oral inflator? I suspect not, but you never know.

You will often find rebreather divers doing this. If I am doing a shallow dive with 32% as bailout I will use it for my suit. I use about 5 bar from a 7l per dive.

I only do that as I have no better choice. I find I take a suit inflate cylinder (which I would use for a deeper dive with trimix bailout) I need to get it filled which is an extra hassle, plus it is all extra kit and complication on an otherwise simple dive.

For a single cylinder OC dive I would not START using the pony as suit inflate gas, but I would be slightly inclined to have a LP inflator hose on it so I had the choice. Once you get to the surface and want all the buoyancy you can get it may be handy. All my stage/deco/bailout regulator sets have one but that is so I can use deco mixes for a suit when doing shallower trimix OC or for various CCR failure work arounds. I don’t take that hose off if I use the 7 as a pony.

 

[seeker242]

This may be a stupid question, but do people put an inflator hose on their redundant air for their drysuit since there is no oral inflator?

Typically no as single tank with air/nitrox, usually don't have redundant air for the suit.

 

[doctormike]

What scenario? No idea - that's why I said it might be a stupid question I don't know what I don't know about drysuit diving, and I am trying to start with as few assumptions as possible.

Not a stupid question at all! I was just pointing out that I have never heard of someone doing that in what I assume is your situation (single tank recreational diving with a dry suit). You would be ascending and you won't need to inflate your dry suit on ascent.

Brendon, you are far more experienced than me, but I don't think that these are scenarios that the OP should rig a second LP hose for. The pony should be his emergency backup, for him it's likely to be a small tank and he shouldn't be using it for anything but that. Yes, the dry suit shouldn't take a lot of gas, but he shouldn't be doing dives where his gas margins are so small that he can't afford to inflate his dry suit with his back gas.

As far as an out of gas emergency, it would probably be far easier for him to orally inflate his BC on the surface than disconnecting his dry suit inflator hose, deploying an LP hose from his pony and attaching that to his dry suit. If he was too exhausted to just blow up his wing, doing that swap wouldn't be any quicker or easier. In that sort of positive buoyancy emergency at the surface, he would be better off dropping weight.

 

[RainPilot]

I agree Mike, just putting all the variables on the table. As I said, I wouldn’t bother myself but there are circumstances where it might be an option, if so then a stowed inflator whip shouldn’t be an issue.

To be clear, generally speaking, you shouldn’t need to bother with a pony to drysuit connection. However if you do feel you need one then be sure to practice the use of it and be aware of the downsides involved.