A need to rehash our discussion on primary donate

[MichaelMc]

@Diver0001, I use two tank OW sidemount for redundancy as it should travel better than doubles; I can use any two tanks. Plus it's easier to look around with no plate fixed to my spine!! I didn't like a pony, hanging on just one side. If one reg is necklaced, half the time side provides faster gas access than a non-necklaced pony. I like how side swims, I don't worry about being back negative and it feels more streamlined than single tank or tiny doubles. Double side is more work gearing up than even tiny doubles, and the hoses are a bit of a Gordian knot (for a non-tech diver), but I want travel redundancy with a well tuned rig.

I dive only mixed teams (with 20x total sidemount dives) as it is all OW with < 100 dive divers.
I think that is the scenario of the new to sidemount OW diver.

My long hose bolt snap is attached to the reg with a bungee loop stretched from the hose above the mouthpiece to over the adjustment knob. If I can't unclip, I can pop that free so it slides down the hose much easier. I have a shortish behind neck necklaced reg. So donate might be primary or secondary.

Not ideal and I welcome reading other solutions. Magnetics are certainly among the choices. Or other hose routings. Solving donate well in sidemount is a good idea, (w/o the Z system).

The double hose / rebreather question seems about how to stow/share the secondary, as sharing the primary isn't an option. Though half the time I donate secondary....

 

[PfcAJ]

@Diver0001 the argument for maintaining primary donate has been kept by the two agencies that still teach DIR. UTD came up with the z-manifold to maintain what is essentially a normal doubles configuration, and ISE uses what is essentially stage bottles.
The biggest issue with sidemounting double long hoses is that you can't put the regulator hoses behind your neck. If you have Poseidons that are non-directional it helps a little bit, or even Apeks/Dive Rite's that are switched, but the hoses have to come straight up to your mouth. In a true sidemount restriction that increases the change of the hose being pulled out of your mouth if it catches on something, and on a scooter it can cause jaw fatigue issues.

Part of this comes down to a situation about diving with mixed teams that @PfcAJ weighed in on a bit earlier. If the whole team is in sidemount, you shouldn't have to ever share gas. If the whole team is in backmount, you have a long hose. If the whole team is on a CCR, you should never have to share gas. In a cave, unless you're doing expedition type diving, there is a risk of coming across a diver that is not part of your team and needs gas. In that case, IMO diving without a long hose is irresponsible. That applies to both sidemount and CCR diving. In a cave, we have the advantage of lights which usually give us enough warning that you are unlikely to get mugged.
In OW, I don't think sidemount is ideal, so I dive doubles and don't have to worry about it. When I dive a double hose however, I have just had to come to terms with not being able to donate the primary.

When diving SM or rebreather or doubles one potential cause for needing to share is contaminated gas.

Don’t be fooled into thinking a particular configuration can make you immune. Reduce the likelihood? Sure. But everyone needs to be able to share.

 

[rjack321]

Not ideal and I welcome reading other solutions. Magnetics are certainly amoung the other choices. Or other hose routings. Solving donate well in sidemount is a good idea, (w/o the Z system).

Tried the magnet thing, huge fail. I went back to a loop of bungie around the mouthpiece with a double ender on that. Have not been happy with a tied off clip, its fine in warmer water and bare hands. In dry gloves, cold hands, a bunch of rebreather stuff (counterlungs, add valves etc) near my shoulders and chest dring in slightly altered positions I don't like having the reg clipped off.

 

[MichaelMc]

With surf exits, giving up a necklaced secondary would be difficult to justify. Or going to an easy breakaway necklace. That's the other benefit of (half the time for sidemount) primary donate.

 

[The Chairman]

I use a double reg bungee. It's tied the same, but there's a short piece of ice maker water tube that separates the two.

 

[ScubaWithTurk]

When diving SM or rebreather or doubles one potential cause for needing to share is contaminated gas.

Don’t be fooled into thinking a particular configuration can make you immune. Reduce the likelihood? Sure. But everyone needs to be able to share.

Call me crazy but shouldn't one check their gas prior to splashing? I smell and breathe off mine before I even head to the boat and 7 out of 10 times I am the one who filled my cylinders.

Now for @tbone1004 , I have been struggling with this as of late in SM. My muscle memory to donate the primary is quite strong. I have worked on many different solutions to the problem and have come to the conclusion, for myself at this time, that I will deal with not donating the primary in SM. I run a longhose left and a short hose right which comes directly up to my mouth (diverite L/R regs). So now, even though I am 99.9% sure which hose I am on, my first movement is to the side of my face area where I would be grabbing the long hose to donate. If there is no hose there, I simply slide down to the d-ring, unclip and donate.

I have spent a few hours in the pool working on this to develop the muscle memory and see it like see diving different rigs as it relates to muscle memory. My bm single wing has a right hand dump valve and my bm doubles wing has a left hand dump valve. My sm rig has a center dump (stealth tec). If I dive the rigs consistently, I never have an issue. When I am diving bm twins for a long time or bm single and then switch to the other bm, it takes me one time to grab for the wrong dump and then I do not make that mistake again.

I do not feel there is a current solution out there that I like which allows for primary donate at all times in SM. So I try and split my dives between each of my three rigs so I am never weak with one. Just my 2 bar worth.

 

[Colliam7]

Several, more general, thoughts in response to Tom's OP. As always, the disclaimer is that these represent my personal preferences.

The vast majority of recreational diving of recreational diving involves an open circuit, back-mounted, single cylinder configuration. In that configuration, primary donate works well, and is the most logical approach for all the reasons we have discussed (over and over) here on SB and elsewhere. I am, personally, firmly wedded to primary donate.

Where divers elect to adopt a single cylinder, sidemount configuration, the set-up is the same as with single cylinder backmount.

The vast majority of back-mounted double cylinder diving is done with manifolded cylinders and, again, primary donate works well and is the logical approach.

These three situations cover A LOT of diving that is done.

For double cylinder sidemount, I use the same hose configuration that I use in back-mount - long hose on the right cylinder, short hose on bungee necklace on the left. I do that simply because I came to SM from BM doubles, and I carried the equipment configuration over. Subsequently, I have tried dual 5ft hoses, dual 7 ft hoses, and returned to what I described above. It is not, technically, primary donate if I am on my left cylinder when an OOA situation develops, and donate my right cylinder second stage. But, since I am regularly using (e.g. switching) the right cylinder and regulator, it is close enough to primary donate 'for government work'. I feel no need to change.

Rebreathers are simply a different situation, as is double-hose open circuit. I don't see a primary donate option. It is what it is. And, while the use of both configurations is on the increase, in terms of total numbers of divers they are still a very distinct minority. I have no problem with special configurations for air sharing with those rigs.

I am not bothered by the absence of absolute total scalability of primary donate to every configuration in diving. It applies in the vast majority of cases, and that's good enough for me.

 

[rjack321]

Call me crazy but shouldn't one check their gas prior to splashing? I smell and breathe off mine before I even head to the boat and 7 out of 10 times I am the one who filled my cylinders.

There has been more than one instance of low/modest (ie non fatal) levels of contamination manifesting itself as dizziness, heavy narcosis, and vomiting/nausea at depth. Either there were no symptoms at the surface or perhaps it took a bit of time to develop.

 

[PfcAJ]

Call me crazy but shouldn't one check their gas prior to splashing? I smell and breathe off mine before I even head to the boat and 7 out of 10 times I am the one who filled my cylinders.

Now for @tbone1004 , I have been struggling with this as of late in SM. My muscle memory to donate the primary is quite strong. I have worked on many different solutions to the problem and have come to the conclusion, for myself at this time, that I will deal with not donating the primary in SM. I run a longhose left and a short hose right which comes directly up to my mouth (diverite L/R regs). So now, even though I am 99.9% sure which hose I am on, my first movement is to the side of my face area where I would be grabbing the long hose to donate. If there is no hose there, I simply slide down to the d-ring, unclip and donate.

I have spent a few hours in the pool working on this to develop the muscle memory and see it like see diving different rigs as it relates to muscle memory. My bm single wing has a right hand dump valve and my bm doubles wing has a left hand dump valve. My sm rig has a center dump (stealth tec). If I dive the rigs consistently, I never have an issue. When I am diving bm twins for a long time or bm single and then switch to the other bm, it takes me one time to grab for the wrong dump and then I do not make that mistake again.

I do not feel there is a current solution out there that I like which allows for primary donate at all times in SM. So I try and split my dives between each of my three rigs so I am never weak with one. Just my 2 bar worth.

Carbon monoxide doesn’t smell like anything.

 

[DandyDon]

What he said...

Carbon monoxide doesn’t smell like anything.