graham_hk(Offline)

First Gledders - thanks for sorting the link thingo - I saw that but had no idea how to fix it

Everything right now - but really for deeper than 70m (wreck and reef) and caves in logistically challenging places. Plus hopefully a few extended dives in Florida.

All of this is my opinion - I won't argue with anybody else's decisions or gear selections so if you disagree - lets agree to disagree (unless you come up with a good idea which I will adopt)

There is no other RB out there that allows so much gas to be carried so efficiently. I like have gas to solve problems in OC - on CCR I was always apprehensive to bailout. This does make the RB80 configuration bigger than many RBs - but compare apples to apples - ie how much gas are you carrying?

I don't like OTS counter lungs so every thing should be self contained (rules out many CCRs)

I don't trust O2 sensors and typically moisture can be a problem on the face of sensors (this is pure speculation but could this be the cause of some of this unexplained deaths?) or computers generally - look at an ipod they hand occasionally for no reason - what is to stop the RB electronics doing the same thing?

In a slightly heads up prone position the WOB was excellent and comparable or better to any RB that I have tried. I don't spend too much time upside down or upright so not too worried about those position where the WOB does suck or blow. In wrecks I just hold my breath for those portions of the dive or grin and bear it or bailout if its extended

I wanted to dive RB for logistical reasons the only choice for GUE diver is RB80.

The only other RB I would consider is MK15s but I sold mine becasue they are a real pain to travel with, if anything breaks you can search forever or pay a small fortune, you can not easily carry large amounts of bailout and despite the best O2 sensor placement I still don't trust the sensors.

Graham

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ah herro

Steve Blanchard(Offline)

Thanks for the report Graham...I enjoyed reading this thread. It makes me look foward to my future RB80 course.

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Roel(Offline)

Hi Graham,

Thank for your clear answer, nice to understand a little more your choice.
I'm not diving RB and no plans yet since OC will be sufficient for me for the current dives, so no big argument (yet) from my side.

First cave 2 and maybe tech 2, we'll see what happens after that.

Enjoy your diving, the plans sound great!

Roel

nskdrs(Offline)

Hi Graham,
Thanks for your detailed report.

I assume, old and new WKPP gasprotocols are different from what is teached in the course?

Thanks,
Hoffi

graham_hk(Offline)

Hi Hoffi

Not sure - I was taught by David Rhea he didn't really say what WKPP does but I assume its what we were taught.


Graham

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nskdrs(Offline)

Ah, ok.

I would think there is a difference in shallow gaschoice and OCswitch depth, as WKPP runs a new protocol, at least when diving in Wakulla.

Well then, enjoy

Here in Germany/Switzerland/France ( assumingly highest pSCR density worldwide ) there are problems with people adopting pSCR ( mostly selftought ) choosing questionable shallow gases too often.

Therefore your report could make a difference, at least some people might get an idea,
how sophisticated training for pSCR could be,
how well a strict approach from scratch would make a big difference.

Thanks in the name of those people,
I hope those in question will read it.


Best,
Hoffi

tim(Offline)

Fascinating report, thankyou Graham! Way ahead of anything I'd even dream of doing, but very interesting to read about how the advanced courses work and reassuring that fundies skills continue to be bugbears even at the top level

One thing remains puzzling me:

I can imagine the buoyancy being neutral with breaths (assuming gas moves from the counterlungs to lungs with no compression so same volume) but can't think of a reason why the volume hence buoyancy would change to negative on moving gas to your lungs. This seems to either imply that the lungs are compressing gas or that gas is being lost from the system (and not replaced) when you breathe in. What am I missing here?

Tim

graham_hk(Offline)

Tim - this is whatI think is going on:

Archimedes' Principle, states that, "Any object wholly or partly immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object."

Your lungs don't displace as much water when you breath in since they are already enclosed in your body (of course your chest will expand a little) than the counter lung. Futhermore as you breath in gas is dumped from the counter lung - further reducing your buoyancy and only injected at the end of the breath.


Graham

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ah herro

David Martin(Offline)

Really? The rest of the body is pretty incompressible and the gas in the lungs is pretty much at ambient pressure, so I would expect that the increase in lung volume and thus the increase in total body displacement to be virtually identical to the volume of gas breathed in at ambient from the counter lung. (With any variation being essentially unmeasureable.)

This would seem to reflect what you're saying, could this be the only reason?

David

graham_hk(Offline)

But the gas is going into a space in your body and thus not causing any more displacement. I would agree but I have seen it in other RBs too where no gas is dumped on inhalation.

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ah herro