An experienced friend of mine (of whom I have asked permission to post this) recently undertook a mundane, unchallenging dive. 25mfw for 42 mins on 32% (twin 12’s) in a puddle, sitting around taking pictures. I was with him on my rebreather using 18/45 and a ppo2 set-point of 1.2.
A painfully slow descent due to my ears saw us @ 25mfw after 4mins where we stayed until 42mins. We then slowly followed the bottom up when he decided that a more direct route to the surface was preferable and his conservative Suunto computer said ok, 1min @5mfw and 3min optional. However, my unit was telling me that 2mins @16mfw were required, so I obliged. Having cleared that obligation, I was presented with 2mins @4.5mfw but a slow crawl around the place saw that reduced to nothing by the time I got there. After a minute he signalled that he was clear to surface and we did.
From 3mfw I took about a minute and a half to surface, by which time he was de-kitting on the pontoon.
Why this post?
He’s heading for an RN62 in the pot for a type 1 DCS in his elbow.
Why?
Mr. Suunto was happy.
PADI 32% RDP would give you NDL of 40mins @26msw.
Z-Plan gives you only 1min@3mfw if you don’t ask it for deep stops.
We think a number of main reasons.
1, It was -1deg on the surface and 5deg at the bottom.
2, His suit leaked at the wrists and he was soaked to the upper arms.
3, He’s not a teenager anymore – sorry mate!
4, Lack of deep stop?
I put a question mark on the last one as the jury is apparently now out again on deep stops. I personally will always agree with them, there’s now way I’m going straight to 3/ 4.5/ 6msw from any serious depth and as long as you’re past the M value line your off gassing, so what’s the harm?
We reckon it’s mainly 1 and 2. You don’t off gas as efficiently when you’re freezing your nuts off. We’re taught in training to add extra conservatism in extreme conditions be they cold or otherwise challenging, but I know that I for one haven’t altered any of my settings from the dives I do in the summer, but it takes something to happen to you or someone nearby to drum it in.
Would a minute or so at mid depth have prevented this? God knows. A bit of 50/80/100%, again who knows? All we know is that decompression theory is not an exact science – according to the RDP, this was not a deco dive anyway!
Would it save a couple of days off work, a drive to the chamber, a five hour £9000 NHS treatment and a good spell away from our favourite hobby plus any subsequent treatments or inconveniences?
Who knows?
Well, speedy recovery mate and thanks for letting me share this. Still it could be worse.......
It could be me in the pot hahahaha!
Sorry! :embarassed:
A painfully slow descent due to my ears saw us @ 25mfw after 4mins where we stayed until 42mins. We then slowly followed the bottom up when he decided that a more direct route to the surface was preferable and his conservative Suunto computer said ok, 1min @5mfw and 3min optional. However, my unit was telling me that 2mins @16mfw were required, so I obliged. Having cleared that obligation, I was presented with 2mins @4.5mfw but a slow crawl around the place saw that reduced to nothing by the time I got there. After a minute he signalled that he was clear to surface and we did.
From 3mfw I took about a minute and a half to surface, by which time he was de-kitting on the pontoon.
Why this post?
He’s heading for an RN62 in the pot for a type 1 DCS in his elbow.
Why?
Mr. Suunto was happy.
PADI 32% RDP would give you NDL of 40mins @26msw.
Z-Plan gives you only 1min@3mfw if you don’t ask it for deep stops.
We think a number of main reasons.
1, It was -1deg on the surface and 5deg at the bottom.
2, His suit leaked at the wrists and he was soaked to the upper arms.
3, He’s not a teenager anymore – sorry mate!
4, Lack of deep stop?
I put a question mark on the last one as the jury is apparently now out again on deep stops. I personally will always agree with them, there’s now way I’m going straight to 3/ 4.5/ 6msw from any serious depth and as long as you’re past the M value line your off gassing, so what’s the harm?
We reckon it’s mainly 1 and 2. You don’t off gas as efficiently when you’re freezing your nuts off. We’re taught in training to add extra conservatism in extreme conditions be they cold or otherwise challenging, but I know that I for one haven’t altered any of my settings from the dives I do in the summer, but it takes something to happen to you or someone nearby to drum it in.
Would a minute or so at mid depth have prevented this? God knows. A bit of 50/80/100%, again who knows? All we know is that decompression theory is not an exact science – according to the RDP, this was not a deco dive anyway!
Would it save a couple of days off work, a drive to the chamber, a five hour £9000 NHS treatment and a good spell away from our favourite hobby plus any subsequent treatments or inconveniences?
Who knows?
Well, speedy recovery mate and thanks for letting me share this. Still it could be worse.......
It could be me in the pot hahahaha!
Sorry! :embarassed: