Rebreather World - View Single Post - What setpoint for 100m+ diving do you use?

Drmike · 13th February 2008, 03:32

Quote: (Originally Posted by rogeringebo)

Hi Mike!
I know you have a lot of experience in deep CCR diving.
What have you learned over the years when it comes to planning the dive, working out bailout, safety factors, algorithms and so on?
Where do you put your po2 on the bottom phase on a dive like this?
It would be interesting to hear about your lessons learned if you would like to share them.

Roger

Hi Roger,

I am conservative.

My approach is 'anything that is unknown is great risk' 'long deco is not a risk'

I can 'manage' deco to make it safe (enough gas, hydrated, habitat etc) but you cant 'manage' the unknowns - so to me they are a greater risk and need to be illiminated or I have to be very conservative with them.

To me O2 tox and CO2 are biggest unknowns and risks

CO2 I manage by diving a unit with great wob, use of scooter and knowing my limits

O2 tox (and efficent lung off gassing) I manage by being very conservative with ppo2s and considering what Im doing when im breathing them (high ppo2 during resting deco is infinitely safer than medium high poo2 during working part of dive)

I dont run unecessary high PPO2s. I take the time to determine if the benefit (slightly shorter run times) outweigh the unknown risk (possible death)

Often theres no advantage to running high ppo2s at depth. Where we need increasingly high ppo2s is during ascent but there is a possible disadvantage as we are on high He mixes and exerting at depth - both contributors to toxing.

Theres still so much we dont know for sure about this stuff. I stay on the loop when possible and dont do air breaks even on 8+hr long dives because I dont take high ppo2s. YMMV

For deco I blindly follow VPM VR3 for all dives regardless of depth and duration (2 VR3 and tables as back up) What works-works

For bailout, you dont have enough. thats what Ive learnt

Best method is to carefully calculate exactly how much bail gas you need then double it - you may then be close . people planning RMV <30 at bottom are deluding the sh1t out of themselves

Big dives im using bail gas and bail Rebreather for added safety and because if you use a realistic bottom RMV its a silly number of stage tanks

For planning; i plan the dive using v-planner, I execute it using VPM VR3. If I bail I bail following Vr3 and likely blow some of the deep stops

13th February 2008, 03:32	#23 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,328	Re: What setpoint for 100m+ diving do you use? Quote: (Originally Posted by rogeringebo) Hi Mike! I know you have a lot of experience in deep CCR diving. What have you learned over the years when it comes to planning the dive, working out bailout, safety factors, algorithms and so on? Where do you put your po2 on the bottom phase on a dive like this? It would be interesting to hear about your lessons learned if you would like to share them. Roger Hi Roger, I am conservative. My approach is 'anything that is unknown is great risk' 'long deco is not a risk' I can 'manage' deco to make it safe (enough gas, hydrated, habitat etc) but you cant 'manage' the unknowns - so to me they are a greater risk and need to be illiminated or I have to be very conservative with them. To me O2 tox and CO2 are biggest unknowns and risks CO2 I manage by diving a unit with great wob, use of scooter and knowing my limits O2 tox (and efficent lung off gassing) I manage by being very conservative with ppo2s and considering what Im doing when im breathing them (high ppo2 during resting deco is infinitely safer than medium high poo2 during working part of dive) I dont run unecessary high PPO2s. I take the time to determine if the benefit (slightly shorter run times) outweigh the unknown risk (possible death) Often theres no advantage to running high ppo2s at depth. Where we need increasingly high ppo2s is during ascent but there is a possible disadvantage as we are on high He mixes and exerting at depth - both contributors to toxing. Theres still so much we dont know for sure about this stuff. I stay on the loop when possible and dont do air breaks even on 8+hr long dives because I dont take high ppo2s. YMMV For deco I blindly follow VPM VR3 for all dives regardless of depth and duration (2 VR3 and tables as back up) What works-works For bailout, you dont have enough. thats what Ive learnt Best method is to carefully calculate exactly how much bail gas you need then double it - you may then be close . people planning RMV <30 at bottom are deluding the sh1t out of themselves Big dives im using bail gas and bail Rebreather for added safety and because if you use a realistic bottom RMV its a silly number of stage tanks For planning; i plan the dive using v-planner, I execute it using VPM VR3. If I bail I bail following Vr3 and likely blow some of the deep stops __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment Last edited by Drmike : 13th February 2008 at 03:42.
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