what tunings are these?

[rack gear]

open tuning - low to high ;

F, F, C, F, A, C

F, F, C, F, F, C

[rack gear]

dan lanois: "I keep it in an open tuning; F,F,C,F,A,C low to high, or sometimes F,F,C,F,F,C."

I'd probably pick the FFCFAC as it gives all three notes of the major triad.

You can also switch to any minor chord by playing the three high strings dropping the third (2nd string) one fret.

I'm not sure what the advantage of the FFCFFC tuning would be.

this site is genius for stuff like this:
Guitar Chord Finder