Long Hose on Primary.

[NeilP]

My regular kit consists of a standard length hosed reg and a long hosed (2m) reg on a twinset.

I have always dived with the primary reg being on the long hose, bungeed against the cylinder, and the standard length reg (secondary) necklaced.

My reasoning behind this is that if I find myself in a position where an OOA diver sees me and comes at me for air - in panic he is going to rip the reg I am breathing from out of my mouth before flapping around looking for the secondary reg. Therefore, with using the long hose as a primary I can let him/her have this, and get some distance between us whilst they calm down, and I can reach my secondary reg without using my hands.

Last night I was getting a fill for last nights dive in the LDS and the owner made an observation about using the long hose as the primary - and that was on a Poseidon course he attended recently, the chap there was stating that when regs are rated with the airflow, etc, this is measured on a standard length hose.

By using the longer hose as a primary, this causes performance issues at depth, because of the distance the air needs to travel to get to it's destination (ie, your gob).

I can understand where he is coming from, and it makes sense.

Anyone got any views on this theory?

[gibbon]

IMHO


yes I think it is rubbish, it is easier for the 1st stage when you have a long hose as you have a larger buffer of IP in the hose.

If the hose was smaller and restricted the flow then it might become an issue but this simply is not the case.

[NeilP]

Thanks Jonny.

I never thought of the buffer the long hose would create.

That makes more sense to me than the original theory.

Cheers.

[Reikimaster]

Originally Posted by jonny

IMHO


yes I think it is rubbish, it is easier for the 1st stage when you have a long hose as you have a larger buffer of IP in the hose.

If the hose was smaller and restricted the flow then it might become an issue but this simply is not the case.

snap,

if you have a short hose then the demand is actually on the 1st stage a longer hose has a reserve which you are able to breath while the 1st stage refills the hose. (try gassing up and then breathing the 2 hoses, there will be v little difference in the initial demand from the 2nd stage but more gas available in the long hose)

on the flip side of the coin, it will take longer for the pressure in the hose to drop before the 1st stage will open so it is a possible argument i suppose.

Depth should not really have any issue (apart from total gas volume moving though the 1st stage, max flow) as the ip is xxx bar above ambient.

ps i could easily be talking out of the wrong hole!

[MarkP]

IF there is a difference it's negligible. The advantages far outweigh this theoretical performance drop.

Regards,

Mark

[Woz]

A reg actually needs the hose length between the 2 stages to work properly- its used as a sort or reservoir. If you put your 2nd stage on a 4" hose the 1st stage will always be trying to top it up while you are breathing causing massive flutter.

[machiavelli]

Originally Posted by MarkP

IF there is a difference it's negligible. The advantages far outweigh this theoretical performance drop.
Mark

I agree that breathing the long hose and donating it has many advantages over donating an octopus and it's a way I would like to set my kit up. There are a couple of reasons I have not done so yet:

I learnt the BSAC way and sometimes instruct in a BSAC club. BSAC requires donating an octopus, using the reasoning that it's better not to have a second diver out of air. I think this is true for inexperienced divers who may be more likely to panic without a reg in their mouths.

As a result, a lot of effort has been invested in training this way, and all club kit is configured this way. If I dived long hose/short hose, would an out of air diver attempt to take the reg from the necklace rather than the one from my mouth?

I usually dive single cylinder and pony, occasionally independent twins. With independent twins you have to swap regs, so you won't know which reg has the long hose until you try and take it. The downside of the octopus with independent twins is that it might be attached to the cylinder with less gas, the upside is that you know which reg it is and can find it easily - it's yellow.

The DIR people are of course right, but there is additional effort in training and keeping current on two different kit configurations, and with that comes some additional risk. It would be great if everyone learnt to breath the long hose and donate the primary, but I can see BSACs reasons for insisting on what they do.

[recurve]

If you are switched on, then you are going to be taking the reg out your mouth yourself, and passing it to an OOA buddy, probably simultaneously picking up your alternate from under your chin and using it. Your buddy gets air sooner and you are in control of the situation.

[NeilP]

Originally Posted by recurve

If you are switched on, then you are going to be taking the reg out your mouth yourself, and passing it to an OOA buddy, probably simultaneously picking up your alternate from under your chin and using it. Your buddy gets air sooner and you are in control of the situation.

Only if they are coming directly AT you. Imagine someone coming from the side, or behind you. No matter how 'switched on' you are, if they are literally 'one breath from death' then they're gonna grab whatever they can.

I'm not not only talking about an OOA Buddy anyway. I don't really believe in the 'buddy pair' system and neither do alot of like - minded divers we dive with. However, let's not turn this into a 'buddy or solo' debate.

Thanks for the responses everybody.

[Janos]

Originally Posted by machiavelli

It would be great if everyone learnt to breath the long hose and donate the primary, but I can see BSACs reasons for insisting on what they do.

Just to clear something up, but BSAC do allow donating the primary. However this is considered to be a relatively advanced technique, and should not be taught to inexperienced divers.

When I dived my twinset, I would breathe the primary if I was diving with an experienced Sports Diver or above, but when teaching AAS to potential OD or SD, or diving with relatively inexperienced divers, then I would breathe my necklaced reg, and used a loop of surgical tubing to secure the 2m hosed reg to my right chest d-ring.

I sought clarification from HQ on this a little while back, and IIRC they were broadly happy with this approach.

Janos