What are the units displayed for SAC?

[rlmalisz]

I have gotten my dives (finally) massaged into MacDive...just in time apparently, since it looks like Suunto has pulled all of the standalone versions of SDM and replaced them with some semi-cloud-based nonsense. Anxiously awaiting for the iOS synch stuff to settle.

In the interim, one thing is still puzzling me: what units are the displayed SAC values in? SDM displays them in SCFM (surface cubic feet per minute), and for my last dive is showing 0.36. For the same dive, MacDive shows "5.75". My units are set to Imperial. The tank in question is a AL80 (aka 77 cubic feet, with a working pressure of 3000 psi (which shows up in the Gear interface of MacDive as "206", which I am assuming is "bar" (shouldn't this number be in PSI if units are "Imperial"?). I am not having anything jump out at me as to how this number maps to my air consumption in terms of units. Anyone know?

--Richard

[findbenjamin]

Richard,
Once I've assigned my tank and the beginning/ending pressures, my Dive Inspector (Cmd-I) under "General" shows x.xx CF/min (which should equate to Suunto's SCFM)

HTH,
B.

[rlmalisz]

Yes, my bad. When my SDM data got imported, MacDive created tanks with working pressures and sizes, but seems to have created the pressures in bar...even though my units were all imperial. Once I changed both the tank size and pressure to imperial, I got pretty reasonable SAC numbers. Off from what SDM shows by about 10% (high), but I can live with that.

--Richard

[findbenjamin]

Hrm, I don't know why they would be off by that much, given that it's formulaic. You might want to consult Nick with a x-post to the support forum.

[nick]

Without investigating further it's likely SDM using the devices "bottom time" versus MacDive using the total length of the dive based on samples.

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