--- In firstname.lastname@example.org, "drdavegoodman"
one among the good windvane is Sailomat 601 . It can be installed
center-aft or off-center.
All the info(and there are a lot) can be downloaded thru the site
In case you decide for such a model I can offer you, at a very good
price, my windvane never used.
I am selling it because I am obliged to change my cruising plane.