Which is precisely why I have a wind vane
for sailing, and will be installing an AP for motoring or motorsailing.
I can justify curtailing the charge going to the battery
banks if I am doing a nice straight line in calm water
(especially if it's sunny), but to use a 10 Ah AP while sailing would make me think "well, if I have THAT to spare, I can put in a beer-only fridge!"
Anyway, having been on a passage
where the windvane
and the AP had issues (both resolved but leaving me with a distaste for hand-steering in lumpy offshore
swells), I couldn't really imaging shoving off with only one means of self-steering.
We haven't even discussed bolting in the tiller and tying bungee cord to the weather