2006 SD Johnson 4 Stroke 9.9-15HP Outboards Service Manual, Page 33Get this manual
INSTALLATION AND PREDELIVERY OUTBOARD INSTALLATION
Transom Measuring and Drilling
Hull Centerline Locate the centerline of the boat transom as it relates to the hull (bottom) of the boatUse straightedge to draw line connecting the port and starboard chinesThe chines should be used as reference points for determining the centerline of the hUllUse framing square to accurately place line on the transomThe centerline of the hull should be in line with the keel of the hull and perpendicular to the midpoint of the line connecting the port and starboard chines
Determine transom height by measuring from the top edge of the transom, along the centerlineUse straightedge as reference to extend the bottom of the boatPosition the straightedge along centerlineThe distance from the top edge of the straightedge to the top edge of the transom is the actual transom height2
1Top edge of transom 2Actual transom height