Gas Management With Sidemount

[wetb4igetinthewater]

Now that I've completed mod 1, I need to see if I can start a thread on rebreathers that will last so many years!

 

[halocline]

My instructor had me switch at my preference and depending on where we were in a cave cause as you know, switching in small areas is a B****, but I'm always open to trying to new ideas and diving methods.

I'm not sure I understand your reply, are you saying that you would have trouble reg switching in a restriction? That's a real problem, unless of course you're talking about a major, no-mount restriction in which case you'd probably be a very advanced SM diver with little interest in discussing reg switching on an internet forum.

Also, I'd be a little concerned about a cave instructor telling a student to 'switch at your preference' although I suspect he probably gave you more specific instructions than that.

Reg switching should be absolutely an easy, one handed, no-problems-at-all skill that you can do in your sleep. And IMO tanks should stay as close to evenly balanced as possible in a cave. In an emergency air share it immediately becomes critical.

In zero vis drills I was taught to switch regs at every tie off, since you can't monitor your SPGs. This is while keeping contact with the line at all times. It's a good drill to run from time to time.

I really don't want to sound judgemental, and I hope I'm not coming off that way. I just think these issues are fairly important for cave diving.

 

[tbone1004]

@halocline what precludes those of us that are experience in no-mount restrictions from wanting to discuss basic sidemount procedures and how we do them when not in squeezy ****?

in some of the squeezy stuff, unclipping the long hose can actually be really annoying, and if it's in a bedding plane you may be wiggling to get through but it's wide enough to not need to no mount. In that case though, we will typically go into the restrictions on the long hose since coming off of it is easy if we have to and the short hose is typically more out of the way when it's not being used, and we also don't really care about the tanks being balanced when doing that section. Once you come out, you rebalance them.

 

[mdwalter]

I do not understand this "cave fill" thing at all.

Cylinders do have their rated fill pressures for a reason. Stick to them. A fill is a fill is a fill.
Open water or overhead should make no difference. The cylinder remains the same.

You can do a cave dive as well with 3600 psi as with 1800 psi. Just turn around when one third of the gas (or less) is consumed.

Yeah, well you could start with half a fill, but then you'll only get about half a dive, too, before you hit your thirds.

 

[Subcooled]

Yeah, well you could start with half a fill, but then you'll only get about half a dive, too, before you hit your thirds.

True, but what is the difference between "a fill" and "a cave fill"???

 

[Six Feet Under]

True, but what is the difference between "a fill" and "a cave fill"???

The tanks are overfilled. It's a common practice in cave country here in Florida. Typically 3500-3800psi.

My PST LP80 steels hold 80 cubic feet of air per tank at 2460psi (rating on the tank), and 117 cubic feet at 3600psi (what they get filled to). That's 74 cubic feet of extra gas, or an additional 24 cubic feet of gas I have for exploring the system I'm diving, before I hit turn pressure and have to begin my exit.