Back-up computer on a JJ

[Janos]

30mins at 80m on .7
leave bottom change set piont to 1.5 ,

about 8 mins more deco than running the full dive at 1.3

tho you could all ways do the same deco as your buddy if he had changed his set piont when he should have , backup for your backup , lol

Mr. Gobbers is spot on.

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Another way to think of it is that each 0.1 of the setpoint is equivalent to 1m in depth.

So a 60m dive on a setpoint of 1.2 is the same from a deco perspective as a 65m dive on 0.7

It makes a bit of difference but not that much during the bottom phase. The real difference is on deco. A 6m stop on 1.2 now becomes a virtual "11m stop" if you're on a 0.7 setpoint. And 6m vs 11m is a big difference...

Janos

 

[Iain3]

Thats why we all carry printed backup tables... we "all" do that don't we? :naughty:

I tried carrying tables for normal dive, and for dive on 0.7 with deco at 1.3 for various depths for various times, but too many variations and at what point might you notice that you didn't change, can't carry a table for every scenario.

Once when my computer failed I just remembered the time to surface last time I looked and counted it down on my depth timer, never looked at the tables anyway.

If I realised I had not changed setpoint I would change up immediately then check the time to surface on the primary computer and compare to the backup. That way if the primary fails I know the backup gets me out the water X minutes too early so stay in that much longer, plus some padding. All academic as I have never forgotten on a dive where the computer then failed.