Per APBA page 160-161 of the handbook
12. X-Dimension - For the 2002 racing season, the Factory I and Factory II Classes will be limited to maximum drive heights. The maximum drive height for all boats eligible to run standoff boxes shall be limited to the centerline of the propshaft being a minimum of 2 ¼” below the bottom of the boat as measured with a straightedge off of the aft running surface directly in front of the drive. (strakes and notches excluded) For purposes of measurement, the centerline of the propeller shaft must be parallel with the aft running surface. All other boats in Factory I and Factory II Classes shall be limited to the centerline of the propshaft being a minimum of 3 ¼” below the bottom of the boat using the same measurement procedure detailed above. APBA Offshore, at its discretion, may further regulate drive heights for parity or safety reasons.