Honda BF115A, BF130A Outboard Motors Shop Manual., Page 441Get this manual
HONDA BF115A-BF130A
Boat Transom Center Line
Measure across the transom to determine the transom center line and draw vertical lineOn "V" bottom boat, the vertical line should pass through the keelUse pencil and tape measure to locate center line1
If dual outboards are to be installed, mark transom at minimum of 13 inches (330 mm) from center line
13in 13in (330 mm) (330 mm)
Put one end of the tape measure on chine and place the other end on the upper edge of the transom, somewhere past the "visual" centerPlace mark on the transom and record the distance measuredMARK