I have an old Aeries on a 31 ft fin keeled boat. from using this i would suggest that a red Fox is too "skittish" for a windvane
upwind they are fine certainly better than an electric autopilot without an in built vane
However, unlike some of the long keeled boats shown already ( & I have had 2) my boat is directionally unstable of the wind.
I suspect that the Red Fox is as well. But of course having not sailed one I cannot be sure.
If it is you will find that anytime the wind is aft of the beam or the wind is abeam & there is a bit of a sea the boat will not respond quick enough to the vane
The boat has to go off course ( by that I mean change angle to the wind not the compass) before the vane picks this up
By the time it does the boat can be surfing down a wave or rounding up. This changes the apparent wind & the vane does not react quick enough
hence the boat is nearly head on to the wind before bearing off. Once it reaches its desired course again the vane then carries on until the boat wants to gybe
Down wind this can be dangerous & I have done a few gybes because of it & if one is in ones bunk it can be a bit of as shock
there are lots of things one can do to reduce this & I would not be without my self steering. Although I would definitely prefer a lighter one such as the monitor
Even things such as stiffening the vane with GRP made a difference.
I spent 2 years getting it to work something like I want, but I still could not risk a really long downwind trip with it.
Even my second Raymarine ST 2000 or my 2 old Simrad 32 s did not really cope very well, hence 4 autopilots in 11 years
At least my Aeries will not burn out