[PATCH] MOD of oxygen at pO2 of 1.6 is 20ft

Rick Walsh rickmwalsh at gmail.com
Sun Jul 5 14:03:09 PDT 2015


On 6 Jul 2015 4:26 am, "Robert C. Helling" <helling at atdotde.de> wrote:
> Hi,
>> On 05 Jul 2015, at 15:09, Dirk Hohndel <dirk at hohndel.org> wrote:
>> But what I've seen in diver training and in blender training (I'm a
certified trimix diver and trimix blender) is that you round to the nearest
foot. Not truncate.

Here people do that, but they also have the big semi-permanent label
indicating MOD down the side.  That is the depth they switch at, which is
always a normal deco stop depth (multiple of 3m /10ft).  21 m (not 22 m)
for 50%, etc.  And the switch depth in feet is always 0.3 x the switch
depth in metres.

Serious question: does anyone switch to 50% at 22m?

For the planner, we need the switch depth, not the true MOD.  Maybe we need
to rename the function to something like gas_switch_depth.  Or we can
create a new function if the current one is used elsewhere.

> I guess that is the best solution: Round to the nearest meter/foot
depending on units. Will later send a patch for this.

To calculate switch depth, I'd be tempted to round to nearest metre.  Then
round down to nearest 5m.  And finally, do a psuedo conversation of 1ft
=0.3m to get the imperial gas switch depth.

I have work to go to, so won't be sending a patch in the next 12 hr.

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