C210 PLT VIOLATED BOS CLASS B AIRSPACE.

Narrative

ON SEP/XA/98; I DEPARTED BVY (NE OF BOSTON) TO THE N WITH THE PLAN OF FLYING N OUT FROM UNDER CLASS B AIRSPACE AND CLBING OVER IT AND PROCEEDING SW TO NEW YORK. MY PRIMARY NAV TOOL FOR THIS WAS AN APOLLO PRECEDUS. I WAS CLBING TO THE W WITH THE INTENTION OF SKIRTING THE EDGE OF CLASS B LIKE A DME ARC. I WAS NOT IN THE CLASS B. SUDDENLY I WAS IN THE CLASS B; I REFERRED TO THE LORAN AND IT CONFIRMED I WAS IN THE CLASS B ABOUT 1.5 MI. I WENT FROM CRUISE CLB TO A FASTER CLB. I WAS NOT SURE HOW I MANAGED THIS ERROR; UNTIL ON MY RETURN TRIP. ON RETURN; I OVERFLEW BVY AT 7800 FT AND PROCEEDED NE AND WAS WATCHING EVERYTHING. WHILE WATCHING THE PRECEDUS MAP DISPLAY; AT SEVERAL MI N OF BVY; THE CLASS B RING DISAPPEARED! I NEVER SUSPECTED THAT THE PRECEDUS WAS UNRELIABLE IN THAT FASHION. WHAT CAUSED MY VIOLATION: BAD SOFTWARE AND TRUSTING GPS ONLY WHEN I HAD A LORAN ALSO. PRECEDUS SOFTWARE VERSION 6.2. HOW TO CORRECT THIS: 1) WATCH BOTH. I WILL. 2) FORWARD THIS TO APOLLO BY EMAIL AND PHONE. I WILL; AND I WILL BE A PEST ABOUT IT.