The number of wraps will not be boat specific.
You could check the manual for your Harken furler but I believe the standard is to always have 3 -4 wraps remaining on the drum when the sail is completely furled including wrapping the sheets around the furler a few times.
I always wrap my sheets 3 turns around the furled sail and that leaves 3-4 wraps on the drum. I've done the same on Furlex and Schaffer furlers.
At the start of the season, if I took the furling line off of the drum, I put about 35 wraps on the drum, install the sail and furl the sail. If I too many or too little wraps on the drum I remove the sheets and add or remove wraps until I have 6 or 7 wraps. I put the sheets back on and furl until I have 3 wraps of the sheets and the drum should have 3-4 wraps of line.
Hope that helps