Analysis of Shearwater Petrel Dive Download

shearwater image
From left to right the colored lines are explained in conjunction with the data box captured at 34 minutes into the dive.
  • The white line is the depth line. Max Depth 94.5 ffw for a one hour and ten minute dive
  • The red box is at the point where the dive required staged decompression at time 34 minutes.
  • The blue line shows a constant temperature of 70 degrees F
  • The green line shows the partial pressure of oxygen throughout the dive
  • The orange line near the top shows the partial pressure of nitrogen throughout the dive
  • The yellow line shows a constant battery voltage
  • The orange ascending line near the bottom shows cumulative CNS O2 percentage
  • The pink line shows the GF% gradual increase with the ascent
  • The PpN2 is 2.61 ata - Compare this PpN2 to that at the end of the last decompression stop.
  • The image below shows the data box at the end of the dive
    shearwater image2
  • Ending CNS was 33%
  • Ending GF was 39%
  • PpN2 was -0.08% since we were breathing pure oxygen, this has been described to me as a "pressure vacancy" which is the crux of acelerated decompression. The pressure vacancy is essentially a large "pressure gradient" which allows/causes inert gas to come out of solution faster, thereby "accelerating decompression".

  • Shearwater NERD2 Download


    This is an image of a download from a NERD2 off of my Choptima Rebreather. Cell mV values are shown.


    Call or text Jim at 352-363-0013