I'm curious about sidemount

[divemonkey33]

Hmmm,

I have been trying to understand sidemounting before I get serious about trying it. But there is something I do not understand about it. Which is it appears that you have two tanks and two regs. Ok simple enough, but lets say you use up all the air in one bottle and go to the next by switching regs. Then at some point now your buddy needs to share air, but now all you have is a reg attached to an empty tank which may not have enough air to get back to the surface safely. I would guess that you would want to leave enough air in the tank for such a case but if you have to reserve half a tank for an emergency then what is the point. Am I missing something? Or is there a sidemount system that has a hose for a manifold? Or maybe I'm onto something here?

 

[Cave Diver]

Sidemount divers switch breathing back and forth between tanks, so they keep a somewhat balanced amount of gas in each tank. If your buddy has a gas emergency, either tank should have enough in it for you to resolve the problem and surface, providing that you followed a good gas management plan.

 

[TSandM]

Well, the basic answer is that you don't breathe one tank empty before switching to the other one. You breathe a few hundred psi out of one and switch to the next, breathe a few hundred psi out of that one and switch back to the first.

And sidemount began as a cave diving technique, where sizable gas reserves are maintained at all times.

 

[Doppler]

Here in the very simplest terms is A BASIC method to manage gas with SM

Begin with similar volumes in each cylinder.
Breathe one sixth of starting volume in cylinder A
Switch regs
Breathe one third of starting volume in cylinder B
Switch regs
Breathe one sixth of starting volume in cylinder A, TURN DIVE
Breathe an additional one sixth of starting volume from cylinder A (it now contains three sixths (1/2) of starting volume
Switch regs
continue to breath from cylinder B until exit (end of dive)

if at some point during exit your buddy needs gas, she will have access to at minimum one half of starting volume
Only THREE reg switches


Come out and take part in a SM clinic at Dutch Springs in the Fall...

 

[divemonkey33]

Thanks good to know, how that risk was addressed. Have to think twice about this now. I like the pros that sidemounts offer, but spending more effort on gas mangement seems like a big con.

 

[Cave Diver]

Thanks good to know, how that risk was addressed. Have to think twice about this now. I like the pros that sidemounts offer, but spending more effort on gas mangement seems like a big con.

The only extra effort (minimal) you're spending is switching between regs. The monitoring of your gas supply should be a part of any type of diving that you do.

 

[beanojones]

Thanks good to know, how that risk was addressed. Have to think twice about this now. I like the pros that sidemounts offer, but spending more effort on gas mangement seems like a big con.

People who want to spend a lot of time on gas management will always find ways to do so. In overhead environments it it necessary, in many cases it is just something that some divers like to do, but it is no more (or less) necessary in sidemount than in any diving.

You can also just keep basically the same amount of air in both tanks by checking gauges and what not.

But, since one of the advantages to sidemount is the ability to add one more tank (to dive with 3 tanks instead of two,for instance), worrying about gas management and switching in that circumstance will just make the dive confusing in many cases.

In that case, it is easier to just go ahead and kill one tank, then trail it, then balance the two remaining tanks.

 

[jago]

You can also use the pony bottle system : dive with a "small" (5,7L - 40cf) and a "big" tank (11,1L - 80cf), use only the small. It's not "elegant" or powerful but it works correctly for recreational, shallow and non overhead water. In case of emergency, the remaining air in the small plus the big one will provide enough gas to reach the surface.
There are many choices available.

 

[decompression]

Thanks good to know, how that risk was addressed. Have to think twice about this now. I like the pros that sidemounts offer, but spending more effort on gas mangement seems like a big con.

Remember, there is single tank sidemount as well.

 

[FoxHound]

single tank side mount is great, def still getting some weird looks when im rigged up though. just a simple glance down and there is my spg, no hands required

as for the gas management.....sure you may have to switch regs which is a pretty simple skill, checking gas pressures is actually easier then BM if you have the spg and hose pointing up.....don't need your hands at all, a simple glance down and you can see both gauges nice and easy