Does anyone out there have trouble with keeping their Raymarine wind instrument calibrated?I have a Hunter 33 with Raymarine wind instruments. Ever since I had the boat new 2 years ago the wind direction indication have been off. I follow the calibration procedures to put in the bias angle to correct the readout but the next time it is off again. The error is in the order of 10-20 degrees.I was told initially that this may be a problem with the windvane set screw being loose. I had some one climb the mast to tighten it and it seemed alright for a while but the boat always seem to sail better on one tack than the other tack. I attribute that to the wind instrument not being dead center.Lately, it is reading off by 20 or so degrees again(compared to the windex indicator). Can the set screw come loose again?Would appreciate any similar experiences and possible fixes.Thanks.