SM Exercises

Well, I ordered my SM package (Nomad with Hog regs) so I was wondering if anyone could suggest some "SM exercises" for me. I am going to be going to Fiji in a couple of weeks and all of the boat diving will be single tank. My thought was that I would BM the single tanks for the boat dives just so that I don't screw up anyone else's day. But, I will also have available unlimited shore diving which should lend itself nicely (I would think) to a novice SM diver trying out a few configurations. I don't know if I wil be permitted to use twin tanks for the shore dives or not. If I do get to take 2 tanks, what is the standard procedure for consuming from them? Do you draw one down a few hundred lb and switch?

I also have a question. I suspect that, since there are so many knowlegeable people here, this has been tried and discarded but I have to ask: Is it possible to take an LP hose from two 1st stages on separate tanks and feed them into a "T" with the center of the "T" feeding a 2nd stage? My first thought was that since you would never be able to get 2 1st stages to be perfectly balanced, this setup would draw one tank down to empty before the second tank began to be used. Is that a fair assumption?

Bert

PS: The abbreviations "SM" and "BM" certainly lend themselves to some serious misinterpretation, don't they??:shocked2:

When breathing the tanks down, you would breath one down about 500 psi, the other down 1000 psi, then switch back to the other for another 1000. If you keep the tanks within 500 psi they will stay close to trim. You can do in smaller or larger increments, but you always want to have a redundant supply of air.

I am going to be bringing my Nomad with me to Bonaire in June and I will be doing all my shore dives in SM.

There is a method of connecting the two tanks, I think it is UTD that has their own system for that, but with careful monitoring you can do without it.

There will be others who are definitely more knowlegable chiming in shortly.

Bert, you draw from each tank equally. You breath about 200psi, and then swap regs, as a beginner.

When you go to your bungeed short hose (left tank), you clip off your long hose reg to your D-ring. A good exercise would spend a whole dive swapping and practicing clipping off without looking.

Also, concentrate on knowing which reg you are on, and practice donating (offering to no one) your long hose. If you are on your bungeed hose, you need to smoothly unclip and offer the long hose. If on the long hose, reg out, duck head, offer and go to bungee smoothly.

So, practice swapping, and practice handing off, and you'll have a good start.

Later, you can do valve shutdowns . . .

no need for the long hose for that type of diving. It is an almighty PITA...
That being said. Couple stages of thought for diving SM.
What was suggested before, swap every couple of hundred pounds. This helps to establish the muscle memory required for doing these switches without looking.
The other school of thought is what I do, mainly because I'm lazy, it's what my cave instructor did, and it makes sense. I switch on thirds.
I.e. My tanks start at 3600psi each. I breathe my right tank* long hose in cave with mixed teams* down to 2400psi. Then switch to my left tank. When the left tank hits 2400psi, it's my "third" and time to turn. From that point, I stay on the left tank until it hits it's bottom third at 1200 psi then switch to the right tank. At this point there is a third of my gas remaining in the left, and up to 2/3 remaining in the right tank leaving an OOA diver with more gas. Which is probably a good thing.

When I'm in open water I switch every 500-1000 psi or whenever I notice the tanks start shifting. Usually switch whenever I feel so inclined if I'm not doing tech dives. Gets the "eh, I'm bored, I guess I'll switch now" which is every 5-10 minutes.

Nomad will work just fine for backmount singles, and as far as exercises, if you have access to an UW camera and/or a pool before you go I'd suggest going there and figuring out where you want the cam bands on the tanks. I measure from my armpit down to where my pants belt is and put the top of the cam band there ish. One thing. If the butts are riding high, the cam bands move UP not down to trim them out. I don't know why it's backwards, but it is up to a certain point. On an AL80 this will end up about the full width of your hand up from the bottom of the boot if they have them, or two ish full hands up from the very bottom.

Thanks for the responses, guys. I will definately try offering my long hose reg to a few fish to see if I get any takers. On second thought, I'm not sure what I would do if I did get taken up on my offer so maybe I shouldn't....

I don't have a good feel yet for what my consumption rate is (probably terrible) so I will keep a close eye on my pressure gauges and swap regs fairly frequently.

On the topic of swapping regs, has anyone tried securing their unused reg with magnets? I read about someone doing that - instead of clips, bungies etc - and it seemed like a good idea to me but I have never done that and I don't know anyone who has.

Bert

I have gate snaps on mine, or butterfly or whatever they're called. Magnets would be way too much of a pita for me... I don't switch very often, and even when I do, one gate clip is nothing in the grand scheme of things. Even if it's a normal bolt snap, no big deal. I have XTX's and I cross them over my neck or they go straight up in front, no suicide strap. So each one gets clipped off when it's done.
If you're donating your long hose, just do yourself a favor and don't fully deploy the damned thing. It's an almighty pain to stuff it back. I hate when I dive with BM divers that insist I give them the full hose during an S-drill. They then watch me have to stuff the bugger back and they usually apologize at the end of the dive, so just practice pushing it forward. The biggest thing is when you're breathing off of your left tank. So practice unclipping the right reg, take one or two quick breaths off of it *makes sure it's working, and also purges it* then donate it and switch back to left. When I was in class I got OOA's I had discussed with my instructor and the other students that if given an OOA, I'd immediately give them whatever regulator I was using, then once they were relaxed and settled and what not I'd give them the long hose so we could exit. Doesn't matter if we were on a stage bottle or back gas, if they are truly OOA, then they want whatever reg is in my mouth at the time anyway. Better to practice that way then just handing them a flooded regulator that may have a piece of something jammed in the lever and not breathe. Just my opinion... Same thinking behind donating on back mount

Very good advice, Tom. I always found the sharing of regs to be a tricky affair. Not because I had any problem with it but because unless you know the person who is OOA very well, you have no idea how s/he will behave in that situation. I learned a long time ago (as a hint, when I first started scuba diving, BC's weren't invented yet :amazed that the most effective process, for me, for starting breathing on a flooded reg is to clear it with your last breath and then breath in slowly. Too many times I have seen divers panic (during a practice, fortunately) when they breathed in a lung full of water from what they thought was a cleared reg. It only takes a drop of water to start a person gagging but if you breath in slowly, the water droplets in the reg won't get past your mouth.

Bert

saxplayer1004:

no need for the long hose for that type of diving. It is an almighty PITA...

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So what do you do in mixed teams? How do you donate a reg?

That being said. Couple stages of thought for diving SM.
What was suggested before, swap every couple of hundred pounds. This helps to establish the muscle memory required for doing these switches without looking.
The other school of thought is what I do, mainly because I'm lazy, it's what my cave instructor did, and it makes sense. I switch on thirds.
I.e. My tanks start at 3600psi each. I breathe my right tank* long hose in cave with mixed teams* down to 2400psi. Then switch to my left tank. When the left tank hits 2400psi, it's my "third" and time to turn. From that point, I stay on the left tank until it hits it's bottom third at 1200 psi then switch to the right tank. At this point there is a third of my gas remaining in the left, and up to 2/3 remaining in the right tank leaving an OOA diver with more gas. Which is probably a good thing.

Click to expand...

Okay, so you're moving along through the passage. You just passed through a tight, silty area, but you haven't hit 1/3s yet so you keep on. You hit 2400 on your first tank and switch to the other and it's full of silt and you can't clear it enough to breathe from it. You turn around but that tight, silty passage takes longer to get through it now because you can't see. Will you have enough air to make it out? I will, because I switch regs every 500-600 psi, which not only leaves me with a larger reserve in both tanks, but also keeps me on top of the operability of both my regs. You might not...

When I'm in open water I switch every 500-1000 psi or whenever I notice the tanks start shifting. Usually switch whenever I feel so inclined if I'm not doing tech dives. Gets the "eh, I'm bored, I guess I'll switch now" which is every 5-10 minutes.

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Your tanks don't start shifting in a cave??

Nomad will work just fine for backmount singles, and as far as exercises, if you have access to an UW camera and/or a pool before you go I'd suggest going there and figuring out where you want the cam bands on the tanks. I measure from my armpit down to where my pants belt is and put the top of the cam band there ish. One thing. If the butts are riding high, the cam bands move UP not down to trim them out. I don't know why it's backwards, but it is up to a certain point. On an AL80 this will end up about the full width of your hand up from the bottom of the boot if they have them, or two ish full hands up from the very bottom.

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It's not backwards, it's a matter of leverage.

In mixed team overhead or with deco there's a long hose on the right bottle. In open water recreational type dives none of my setups have a "long" hose. The backmounted stuff get a 40" under the right shoulder which is enough for vertical ascents. In sidemount each tank is on a 40" across the back of my neck which is fine for vertical ascents, and long enough for limited side by side kicking.

I don't squeeze through the really tight stuff, so I haven't come across a situation where that would matter, and I haven't noticed my tanks shifting noticeably with thirds. I don't know if I compensate for it by shifting air in my wing or what, but I haven't noticed flying thru a cave. On the regs working though, does that mean that every few hundred PSI that the guys in doubles should check their octo for breathability? because I have yet to see a guy diving doubles breathe on their octo every 15-20 minutes... I know they probably should, but unless you are kicking up silt or sliding through it whether it be in the water column already or because you are squeezing I just haven't come across the problem by switching on the third on each tank. Different schools of thought I guess, and for the type of diving I do vs the type that you do it's different. Sidemount for me was lifestyle because of my joints, never intend on going through true sidemount passages where that would be a problem.

I know it's leverage, but it's backwards from what some would think with tanks being light in the butt and what not. I had it backwards until I watched a tank shift on a buddy of mine and the light clicked that it was teetering on the cam band.

Bert,
I'm assuming you are going to be diving aluminum 80's. That being said, you don't want to dive down to thirds before switching. You will have one tank hanging low and one high. Listen to Rob and switch more often. If this seems like to much work, or task loading, then you shouldn't be diving sidemount. And be aware, when using the rails on the buttplate of the Nomad with Al80's, if your tanks aren't weighted, when your tanks get buoyant, they are going to ride up. You'll basically look like the Starship Enterprise. Better to use the double d-ring solution that Bogaerts uses.