Given the size and relative speed of your boat, I would suggest that somewhere around 60 degrees should work well for you. Even if you don't get it perfect, as tigerregis points out, read how to use the instrument properly and it will still tell you all that you need to know once you get used to the normal tail to square positions for various wind speeds and wave conditions. The next step is to add teletales to the leading edge of your
jib.
Jeff