Considering a Rebreather....

[JohnnyC]

A BOV by it's very nature has an open circuit second stage built into it. If it doesn't, it's a DSV, a dive surface valve.

Calling it an OCB is pretty much just APD trying to be different. Get a Shrimp, it's a better design anyway.

 

[The Chairman]

Can you speak "English" so I can follow? Remember the OP (me) is a layman (although I've heard of a Shrimp BOV - no idea how it differs from others

So sorry...

The SF2 has different size bores on it's hoses. 40mm on the "head" (contains the electronics and is the top part of my SF2) and 44mm on the DSV. Consequently, going to a BOV (A DSV with a built in second stage). I had to change hoses. Now, the SF2 hoses are among the shortest out there already as they go straight from the head to the DSV. The Cooper hoses I went with are even shorter and the valleys of the corrugation are very narrow and in a tight spiral. This makes them a very quiet hose and the shortness helps keep the mouthpiece in my mouth. They don't seem to cool off the air as much either. This leads to a lot less condensate in the loop which can become bothersome to me.

 

[The Chairman]

The main function of both the DSV (Dive Surface Valve) and the BOV (Bail Out Valve) is to maintain the water tight integrity of the loop. The loop must keep water out of the loop. Whenever the mouthpiece comes out of your mouth, the loop must be closed off to water at all times or you might create a toxic cocktail.

In addition to protecting the loop, the BOV supplies open circuit gas to the diver. The first thing you learn as a RB diver: When in doubt, bail the F*** out. With a DSV, the diver closes off the valve, releases it, pulls the Bail Out regulator to themself and the purges it in order to take their first sanity breath. With a BOV, you simply turn the valve and start breathing. To get back on the loop, the diver has to roll backwards a bit so they can grab the loop, pull it down, put it in their mouth, purge the thing, turn the valve on and then restow your bail out valve. To get back on the loop with a BOV, again, you just turn the valve.

 

[Diving Dubai]

@NetDoc @JohnnyC

Thank you, Really, that was exceptionally interesting.

One thought (irrational as it maybe) but the big hoses and the valves etc on the mouth piece. Is it heavy or uncomfortable at first as it sure looks unwieldy.

I appreciate all that I know about diving thus far including techniques amounts to squat and I'll be starting at the beginning almost like a OW, and I'm sure that once in a Unit certain things will become apparent, but I've always wondered about the mouth pieces

 

[The Chairman]

DSV stands for "Dive Surface Valve". It was defined earlier, so I didn't repeat it. Interestingly enough, while do use it on the surface, you also must use anytime you bail while at depth.

 

[The Chairman]

Is it heavy or uncomfortable at first as it sure looks unwieldy.

Not in the water. We have to add weights to get them neutral. BTW, that reminds me. I have to add some more to mine.

 

[ScubaInChicago]

With a BOV, you simply turn the valve and start breathing. To get back on the loop, the diver has to roll backwards a bit so they can grab the loop, pull it down, put it in their mouth, purge the thing, turn the valve on and then restow your bail out valve. To get back on the loop with a BOV, again, you just turn the valve.

The whole rolling backwards thing sound like the beginning of a big CF.

 

[PfcAJ]

The whole rolling backwards thing sound like the beginning of a big CF.

yea...rolling backwards? wut?

 

[The Chairman]

The whole rolling backwards thing sound like the beginning of a big CF.

It's just physics. When you are prone, the loop floats straight above your shoulders. Roll back a bit and the loop stays put, but now it's a lot easier to reach.

 

[KenGordon]

The whole rolling backwards thing sound like the beginning of a big CF.

I don't need to do this, the T pieces (where the breathing hoses meet the counterlungs) are more or less by my ears, so do not have to reach far to get the loop back.

There is no standard BOV for my JJ. I would probably prefer to have one. When more confident about messing with it I may fit one. I asked Jan at a show it they are likely to redo theirs with CE. I was told to take care packing my scrubber and avoid over exertion.

I see the OCB as an advantage of the inspiration, but still decided on a JJ. On the inspiration I think there is an o ring which you remove when filling it which you can forget to replace and allow bypass. The JJ goes not. Still, I could get hair or rubbish in the wrong place to the same effect, or swim too hard, or fail to change the sorb.

To have a BOV or not is a contentious subject.