Wakulla Springs B-Tunnel Video (WKPP)

[rddvet]

kelemvor, CCR’s have a tremendous amount of capability in a small package, 10 hours strapped to your back. But, there are some other significant considerations involved that make the RB80 an equal or better choice in some cases.

I’m surprised GUE didn’t go with the SF2 when they developed their CCR program. It’s basically just an RB80 with a solenoid and a different bellows setup.

And electronically driven, which automatically rules it out. Wasn't there an SF rebreather that was kind of between the RB80 and the SF2 that was fully closed, but not electronic? I would've thought that would be a contender over the SF2, though never thought either would.

I wouldn't be surprised if the Fathom gets a close look though, but I doubt WKPP/GUE really has any reason to switch from the RB80

 

[PfcAJ]

The scrap of efficiency gained from a ccr just doesn’t outweigh the added complexity.

For reference, I used 37 cubic feet of 10/85 on that dive (roughly 65mins at 270’). That’s including wing inflation.

 

[JohnnyC]

The GUE JJ is electronically driven. I should have been clearer with my comment. I should have said I’m surprised they chose the JJ for their eCCR as opposed to the SF2. Interestingly enough, the SF2 scales far better than the JJ, which is one of the great things about the RB80.

Scubaforce had the SF1, but it was just another of the RB80 clones coming out of Europe. I don’t know if they had an mCCR at any point.

 

[Lobzilla]

The scrap of efficiency gained from a ccr just doesn’t outweigh the added complexity.

For reference, I used 37 cubic feet of 10/85 on that dive (roughly 65mins at 270’). That’s including wing inflation.

Wow. Did that require a special bellows ratio?
And somewhat related, how do you deal with the larger difference between gas FO2 and loop FO2 in shallow depths? Do you switch to OC, dump loop volume through nose when coming up, or just rely on previous experience with an O2 gauge?

 

[PfcAJ]

Wow. Did that require a special bellows ratio?
And somewhat related, how do you deal with the larger difference between gas FO2 and loop FO2 in shallow depths? Do you switch to OC, dump loop volume through nose when coming up, or just rely on previous experience with an O2 gauge?

Nope. Just a a good sac rate and good loop management. The unit mechanically is 10:1. 8:1 is pretty reasonable in practice and I tend to hover around there, especially if I’m just chillin’ on the scooter and not doing anything taxing.

Ask 10 rb80 Divers and you’ll probably get 11 different opinions on dealing with the po2 drop.

Personally, I vent the loop pretty often on deco and “ignore it” as far as tables and my computer are concerned. I understand that I doing that increase my DCS odds a a bit that but it seems to work fine.

I do NOT ignore the drop when driving the rebreather with gases that would be hypoxic in the shallows. For instance, 300 gas (10/85) is hypoxic through the rebreather shallower than about 130’. Hypoxia is probably th biggest risk with the RB80, and it’s also the most insidious.

 

[KevinNM]

Googling USDCT I found this

So that is the tomahawk guidance package guys?

 

[karstdvr]

that could be. the USDCT used some wacky mapping thing in there I think

I think the original Wakulla 2 (USDCT) project featured a sonar mapper developed by Bill Stone, that has developed into Sunfish. Would be very cool to see accurate maps of these cave systems.