Choice of Dil for Surface Swim

[ardhill]

Hi

I was on a boat the other week with a RB diver and he asked the skipper to drop him as close to the shot as he could. He didn't want to surface swim as he was using 10/50 dil and said it tired him out too quickly on the surface.

Now, this confused me a bit as it was eCCR, surely the unit would pump in more O2 and wouldn't have him breathing pure 10/50? Or is there a factor to the quantity of Helium over Nitrogen being breathed to increase fatigue? Or is it his imagination?

Thanks
.

[David Pye]

Weird, that!

Yeah, as you say, if he's on ECCR, that ought to bring the O2 content to maybe 70%, assuming his setpoint was 0.7 bar on the surface.

Perhaps he's just a bit fat and lazy?

[RichardGreen]

Originally Posted by ardhill

Hi

I was on a boat the other week with a RB diver and he asked the skipper to drop him as close to the shot as he could. He didn't want to surface swim as he was using 10/50 dil and said it tired him out too quickly on the surface.

Now, this confused me a bit as it was eCCR, surely the unit would pump in more O2 and wouldn't have him breathing pure 10/50? Or is there a factor to the quantity of Helium over Nitrogen being breathed to increase fatigue? Or is it his imagination?

Thanks
.

Your right total bull shit, initial set point would be .7 so shed loads of O2.


Richard Green

[al kennedy]

i know there are issues with low O2 mixes on open circuit at the surface and in shallow water, but i understand that he should be breathing around 70% on the surface depending on his set-point?

would suggest he needs to do his swim-test again!

or he is spoofing to get dropped on the shot

or he is imagining it

or there is a fault with his CCR

[turbanator]

Have a look at this thread on RBW, I don't recall if Keith posted it here.

After reading Keith's (extremely frank) report, I don't think that being dropped near the shot is the safest option in this instance.

r
P

[Depth-junkie]

Originally Posted by ardhill

Hi

I was on a boat the other week with a RB diver and he asked the skipper to drop him as close to the shot as he could. He didn't want to surface swim as he was using 10/50 dil and said it tired him out too quickly on the surface.

Now, this confused me a bit as it was eCCR, surely the unit would pump in more O2 and wouldn't have him breathing pure 10/50? Or is there a factor to the quantity of Helium over Nitrogen being breathed to increase fatigue? Or is it his imagination?

Thanks
.

Imagination pure and simple.

The only way this would be a problem was if his elecs or 02 were turned off.

If the unit was switched on and the 02 also on as well, the unit would be holding low setpoint (0.70) which aquates to an 02 content of 70% at the surface or 43% 02 @6m.





ATB
Gareth

[ardhill]

Thanks Guys you helped settle my mind on this.

I am still learning about CCR, so for all I know there could have been an issue, but I had never heard of something like that before.

Personally I think the guy is a bit unfit from other things I have noticed in the past. And the sea was a bit choppy and the current was running so...
.

[onthetrain]

Originally Posted by ardhill

Hi

I was on a boat the other week with a RB diver and he asked the skipper to drop him as close to the shot as he could. He didn't want to surface swim as he was using 10/50 dil and said it tired him out too quickly on the surface.

Now, this confused me a bit as it was eCCR, surely the unit would pump in more O2 and wouldn't have him breathing pure 10/50? Or is there a factor to the quantity of Helium over Nitrogen being breathed to increase fatigue? Or is it his imagination?

Thanks
.

He's talking bollocks. He would be breathing 70%

It would be very interesting if he forgot to switch his o2 on though

Alan

[ardhill]

Originally Posted by onthetrain

It would be very interesting if he forgot to switch his o2 on though

He was pre-breathing on the boat and didn't fall over, so I guess it was turned on
.

[Mick F]

Originally Posted by ardhill

Personally I think the guy is a bit unfit from other things I have noticed in the past.

Now I know it wasn't me coz I had an air dil*. So it must have been that fat barsteward Midnight.

*That and the fact I'm so fit and svelte