I have a hydraulic setup with two
helm stations that will use a ComNav or similar AP, but with the turn of a handle, the hydraulics can be bypassed in favour of a Voyager windvane attached to a seven-foot tiller.
Inshore, or while motoring, the hydraulic/AP combo is preferable.
Offshore and on
passage, down to about eight knots apparent
wind, the windvane/tiller is much more pleasant on a number of levels.
The point is twofold, literally. I have two means to self-steer that are completely independent of each other. Aside from suggesting rather rare and old
books like Tony Meisel's Single-handed Sailor, I would suggest you
experiment with your vane and tiller, which may require many repositionings of turning blocks and line tensioning before you find what works.
Once done, however, you'll have a reliable method of self-steering in most conditions.