Help with configuration

[Mong]

Hi folks,
I'm setting up my first twinset and would like to ask how those with more experience in these matters do so.

My first idea is to have primary regs and octo on the right-hand tank. SPG, inflators and secondary regs on left - with 2nd stage going to the right - behind my head and round my neck on a long hose.

I figured that I'd do without the SPG on the right-hand tank as - if I lose a tank - after isolating, it's back up to the top time.

The main thing that I was umming and ahhing about was an octo on the second tank.

Does this configuration sound sensible, or have I missed something obvious?

Many thanks for any suggestions.

 

[David Evans]

Mong, I'd recommend you get some training on using a set of dubs from a qualified instructor... it's pretty important that you have a solid understanding of the operation of the isolator and valves, and how to diagnose potential problems with them underwater.

Diving a set of dubs is nice, because it affords you additional redundancy and a lot of extra gas. But extra gas often times means diving in a "hard overhead" in the form of deco obligations, which means that dealing with problems underwater is a requirement... not an option. And while the dubs bring added redundancy, they also bring added failure points that you MUST understand.

Anyway, assuming you know all this already (sorry for the lecture), what benefit would there be to having three second stage regs on your setup (as it seems to me you are planning)?

I agree with your rationale about not using a second SPG on the right tank... that's another failure point (in this case, a high-pressure failure point!), and if you are managing your gas properly, you should be able to make a safe ascent with your tanks isolated even without an SPG if you have a major left post failure that requires isolating the tanks.

Anyway... think it through. What are the risks/rewards of that third second stage? What circumstances would cause you to need it? How likely are they?

Your message wasn't clear to me... are you considering three second stages, or four? Or have I misunderstood entirely?

-d

 

[Mong]

Thanks for the information. I already have the training booked - pool sessions to practice the drills and then an inland open water to try in a controlled environment.

I was wondering about three second stages - primarily because I have a couple of decent second-stages that I was going to use as the to primary regs, and then the good-old bright-yellow backup that folks can see and grab should I assist in an out of air scenario (as opposed to the nice black one that was in my gob when someone grabbed it last time). The rationale being that novice divers, out of air, probably having seen very few twins are, hopefully, going to do what they've been taught and go for the yellow one on your chest.

In a way, this just mirrors the pony setup with two on the main and a single on the pony.

 

[Eric__U]

The way the majority of people have their regs setup when using an isolator is to only use 2 second stages. Your primary with a 7' hose on your right post and your secondary bungied to your neck from your left post. In the event of an gas emergency you hand of your long hose and switch to your other reg bungied around your neck. There is no need for more then 2 second stages.

 

[MechDiver]

The way the majority of people have their regs setup when using an isolator is to only use 2 second stages. Your primary with a 7' hose on your right post and your secondary bungied to your neck from your left post. In the event of an gas emergency you hand of your long hose and switch to your other reg bungied around your neck. There is no need for more then 2 second stages.

Correct. Also, you do not have both inflators on the left post. Your wing/BC inflator comes from the right post, the drysuit from the left. Same with second stages; your primary comes from the right, secondary (necklace) from the left.

MD

 

[simbrooks]

As much as i dont know about certain aspects of diving, i believe the reason for putting the back-ups on the left post are due to the possibility of roll-off, that is you dont give the left post reg off to you buddy as it could roll-off leaving them with no air, whereas you can tell its being rolled off and can turn it back again.

I can understand having one inflator per post, but is there a reason for left-drysuit and right-wing? Surely as the wing's inflator hose is on the left, wouldnt you put it the LP hose on that side, or is it to take up some slack in the length of most LP inflator hoses (in which case, why not buy a shorter hose?) by tucking into that gap under the valves where the hoses criss-cross?

Also isnt a deco obligation a "soft" overhead, you cant break through it without hurting yourself, but its not "hard" like a cave ceiling or wreck structure - semantics.

As for passing off the long hose, or to rig it for someone to grab it off you when they need it, some people put the yellow faceplates of their octo's on their primary 2nd stage, others have the donating reg on a 7ft yellow hose and breathe off that until they donate it. Not sure how the rest of the diving public (or tech crowd) think of this, whether it causes confusion that you are breathing off the reg with octo colours - but in an emergency at least they can see either the yellow faceplate or hose and know which to go for. The faceplate swap was how i have set-up my single on a long hose - although i have tried doubles, they were borrowed from my instructor and therefore i have yet to put a set together.

 

[MechDiver]

As much as i dont know about certain aspects of diving, i believe the reason for putting the back-ups on the left post are due to the possibility of roll-off, that is you dont give the left post reg off to you buddy as it could roll-off leaving them with no air, whereas you can tell its being rolled off and can turn it back again.

Correct, mostly.

I can understand having one inflator per post, but is there a reason for left-drysuit and right-wing? Surely as the wing's inflator hose is on the left, wouldnt you put it the LP hose on that side, or is it to take up some slack in the length of most LP inflator hoses (in which case, why not buy a shorter hose?) by tucking into that gap under the valves where the hoses criss-cross?

You separate the inflators for redundency. If you have to shutdown/isolate a post, you still have gas and inflation from the other side. The inflator hose from the right post works well and does not interfere with anything if routed correctly.

Also isnt a deco obligation a "soft" overhead, you cant break through it without hurting yourself, but its not "hard" like a cave ceiling or wreck structure - semantics.

Kinda. If you've done a 200+ foot dive on trimix, you have a hard ceiling. True, you **could** make a direct ascent, but unless you had support and fast access to a chamber, you would not enjoy the ride. I consider any required deco a hard ceiling.

As for passing off the long hose, or to rig it for someone to grab it off you when they need it, some people put the yellow faceplates of their octo's on their primary 2nd stage, others have the donating reg on a 7ft yellow hose and breathe off that until they donate it. Not sure how the rest of the diving public (or tech crowd) think of this, whether it causes confusion that you are breathing off the reg with octo colours - but in an emergency at least they can see either the yellow faceplate or hose and know which to go for. The faceplate swap was how i have set-up my single on a long hose - although i have tried doubles, they were borrowed from my instructor and therefore i have yet to put a set together.

None of us use a yellow faceplate on the 7 foot hose, that I have seen anyway. It isn't needed due to training and team awareness as long as you are breathing it. If you should choose to coil the long hose and bungee it to a tank, then a yellow hose and yellow faceplate would be appropriate IMO.

MD

 

[Boogie711]

Correct. Also, you do not have both inflators on the left post. Your wing/BC inflator comes from the right post, the drysuit from the left. Same with second stages; your primary comes from the right, secondary (necklace) from the left.

MD

And there's a big time huge reason for splitting your second stages/inflators:

If you have to shut down a post and isolate, it does you no good whatsoever if the post you have to shut down contains both second stages, does it?
-----------------
Sim - Yes, there is a good reason for left = drysuit, right = wing. If you experience a roll off and breakage (eg, you smack the ceiling, knob rolls off and then breaks.)

The unit that just shut down is the left post, since that's the way it rolls to shut down. The right post would break off in the open position. Therefore, your primary post contains your primary reg and primary source of bouyancy - your wing.

If the absolute crap hit the fan, it wouldn't be pleasant, but you could still donate the primary and breath off your wing. You can't breath off a drysuit inflator.

 

[simbrooks]

None of us use a yellow faceplate on the 7 foot hose, that I have seen anyway. It isn't needed due to training and team awareness as long as you are breathing it. If you should choose to coil the long hose and bungee it to a tank, then a yellow hose and yellow faceplate would be appropriate IMO.

I was thinking more in the rec diving times, when those who dont have similar set-ups are diving with you, some need a bit of a clue as to which reg to grab (even if you discuss in pre-dive briefing). Also given the fact that most reg sets are sold with one yellow and one "other colour" faceplates, which would you rather a rec diver who is OOA grabbing - the one in your mouth that is or isnt yellow, or around your neck that is or isnt yellow (i know you donate the one on the 7ft hose you breathe off)? Most essentially untrained divers (ie those not used to the rig, but still certified) would go for the yellow one regardless of where it is. Before you scan that without reading it, let me reiterate - they would grab the yellow one most likely, you dont want them to grab the one around your neck - they wont get it all that far, so how would you set that one up to make it easiest for them? This is assuming they come up to you panicked (ie not thinking straight, fairly common - how many times do we hear about divers like that?) and take the reg from you - i would prefer that to be the one in my mouth on the long hose - therefore to do so they would like to see yellow and i happen to have one yellow ane one gray faceplate from my first reg set-up - guess which i will put on the donating reg??? Yes i could buy another faceplate, but i havent been to the dealers store in a while, been diving (getting other fills elsewhere) or on vacation instead. Of course a "trained" diver would know and have practiced this plenty of times, so in a technical dive they would know what they were doing most likely and colour wouldnt matter to them.

I understood the reason for seperating the 2nd stages and inflator hoses over the two posts(i left out the words "for redundancy" from my last post), just not the reason for left=drysuit and right=wing and not right=drysuit, left=wing. I dont dive dry so cant be sure, but arent the connections on the end of the LP inflator hoses for the wing and DS the same - ie you could unplug one and put it in the other? Any kind of trouble with a failure requiring a post shutdown would be cause to turn a dive and mostly that will mean ascending or going along at a similar depth til the deco/ascending point - ie mostly a little dumping from the two main air pockets rather than a lot of air adding - unless in some kind of sump or wreck where you might have to go down a bit to get up and out. As such i guess you could deal with neither LP hoses being plugged in - even inflating manually on the wing. So is it a hose routing reason for putting one on the right and the other on the left in that order and not the other way around? I also understood the primary buoyancy device on right post arguement, again if you can interchange the two hoses on the inflation points what is the trouble? Just seems sensible to put the wing LP inflator on the left post as that is the side where the actual wing inflator hose is and have things coming down over the left and right shoulders linearly and directly than criss-crossing around the back (unless you want to stow a bunch of hose that is too long). Or am i still missing something? From wearing a set of doubles for a couple of fairly shallow dives/hours i saw and felt how hoses were routed on that set, i know that makes me nothing like an expert in this, just somethings arent that obvious, unlike a whole host of other diving practices.

BTW, if someone is mostly correct or whatever other phrase may be used, please point out where the margin of misunderstanding is, so that the answer in my head is correct and not mostly correct

 

[Boogie711]

If or when the crap hits the fan, do you really want to play around with unplugging this hose, unplugging that hose, rerouting this other hose, reconnecting this hose, etc. etc. etc.

Especially because no, a drysuit inflator may NOT necessarily connect with a wing, or vice versa... the hoses are designed to reach the point they need to, not all the way back over to the other attachment.