SM Exercises

[BertP]

I think I will try a number of different techniques. When shore diving, I may even let my 1st tank go down to 50% just so I can get an idea of what it feels like. Of course, if it gets too cumbersome, I will stitch before I get down that far but I would like to know what "imbalanced" feels like when I am just fooling around rather than finding out at a more inopportune time.

Bert

 

[tbone1004]

With AL80's you notice a lot, with my PST's, I honestly don't notice a tank shift at a third. I may compensate for it without thinking, but even when I ended up with one tank at 3300 and one at 1500psi *had a first stage failure, long story, but had a full tank on the right side* the shift wasn't that bad. I keep my cam bands relatively low since I have a long torso and an extra long transpac.

With the AL80's, you may want to move your hip D-rings back a little bit and when they get lighter switch them to the hip D-rings instead of the butt. There's a youtube video demonstrating this somewhere

 

[Colliam7]

I was wondering if anyone could suggest some "SM exercises" for me. ... 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.

Is the shore diving 'supervised' in any way? If not, I am not sure why you would be 'permitted' or 'not permitted' to dive SM. I haven't been to Fiji, so my comment may come from ignorance. But, using Bonaire as an example of another location with lots of shore diving, you can do virtually anything you want to do with your shore diving - and I just take out two (or four) tanks and rig them for SM and away I go.

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?

You have received several good suggestions for the amount of drawdown on each tank before you switch. All are reasonable - e.g. keeping the tanks within 200 PSI of each other, or within 500 PSI of each other, or drawing down by thirds. (In fact, some of us get lazy at times in shallow OW and draw one down to 500 PSI, then switch to the other - I am not recommending that, BTW). Since you asked the question in the context of exercises that will allow you as a relatively new SM diver to pracice skills, I very much agree with Jax - practice at this point with smaller increments (keep the tanks within 200 PSI) to improve 'muscle memory' factor. The practice never hurts.

I fully appreciate what saxplayer1004 is saying about the PITA factor on the long hose, but I will disagree with the recommendation. I would go ahead and use the shore diving to practice deploying the long hose on the right, AND re-stowing it. Yes, it is a bit of a PITA, but that is exactly why it is good to practice it.

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.

I have not tried it, although I have seen comments that some people do it. I use a bolt snap to secure the right side (long hose) second stage, and a bungee necklace to secure the left side (short hose) second stage. Those configurations seem more secure, but others may have better experiences with magnets.

One other thing to consider as 'practice', given the discussion about trim as tanks empty out: if you are using cam bands, such as the 1.5" cam bands that DR sells along with the Nomad (or a couple of 2" cam bands), you can practice shifting the position of the cambands, DURING the dive, to get a feel for how the cam band position on the tank affects your trim. (If you are using stage bottle rigging, this really isn't possible, other than shifting the point of attachment of the lower clip on each tank, from the buttplate to a waist D ring, for example.)

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 stage s 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?

I may be the only one, but I am not sure I understand exactly what you are proposing to do here. It sounds like you would use a single second stage and regulate air use by your tanks valves.

 

[tbone1004]

re. the last question. I think he's getting at something similar to the new UTD system with a manifold block, or something along those lines. At that point you lose the truly independent nature of the sidemount system and it gets awfully bulky
http://www.scubaboard.com/forums/dir/370515-new-utd-rig-thoughts.html
http://www.scubaboard.com/forums/side-mount-divers/366335-playing-utd-z-system.html
couple of big threads there

 

[BertP]

I may be the only one, but I am not sure I understand what you are proposing to do here.

Basically, each tank has its own 1st stage and the LP lines from those two 1st stages go through a "T" and into a single 2nd stage. It would be similar to normal BM twins but instead of having a hard manifold connecting the two tanks, you would have a soft hose connecting them. Probably not a good idea anyway, but I thought I'd ask :blinking:

Bert

 

[gearhound]

He's talking about the UTD system, a solution looking for a problem.
I'm assuming that since he is going to Fiji, that he will be diving AL80's. If so, deploying and re-stowing the long hose is rather easy. You can unclip the tank and stuff the hose away. If you're just starting out, might as well start out right, rather than developing bad habits right away.

 

[BertP]

Just for clarification: I am not getting anything to join the tanks nor do I plan on joining them at this point. It was just an idea that hit me and I thought I would ask here to see if it is possible or advisable.

I have also never dived (dove?) with side mounted tanks so I am a complete newbie in this area. I don't even have my equipment yet (ordered last Saturday).

Bert

 

[tbone1004]

watch all of the videos on the diverite website... They are immensely helpful

 

[Colliam7]

At that point you lose the truly independent nature of the sidemount system and it gets awfully bulky

Thanks for the link, I thought that was the case but wanted to be sure. I agree - I like SM for the very reason of true independence [and REALLY easy valve shutdowns ] I am not sure why you would want to lose the redundancy.

 

[Colliam7]

Basically, each tank has its own 1st stage and the LP lines from those two 1st stages go through a "T" and into a single 2nd stage. It would be similar to normal BM twins but instead of having a hard manifold connecting the two tanks, you would have a soft hose connecting them.

OK, I have now also looked at those threads, and it IS a 'soft' manifold, and you DO regulate gas by turning valves on and off. Honestly, I would not try to add this factor in at the beginning of my sidemount diving. Maybe, I am being too conservative (or just an 'old fuddy duddy' as my daughters say) but I would probably focus on working on rigging and trim, and gas switching, and becoming comfortable with with my rig.