2004 SR Johnson 2-stroke 40, 50HP Service Manual, Page 35Get this manual
INSTALLATION AND PREDELIVERV TRANSOM MEASURING AND DRILLING
TRANSOM MEASURING AND DRILLING
Inspect Transom Area
Transom Clearances Make sure the transom and splash well area provide adequate outboard clearancesConfirm that the proposed mounting hole locations will provide adequate clearance for mounting bolts and washersCheck the inside area of the transom for obstructions prior to drilling mounting holesWater Flow Inspect the hull area directly in front of the hull's centerlineBoat-mounted equipment should not create turbulence in the water flow directly in front of the outboard's gearcaseTurbulence or disruptions in the water flow directly in front of the gearcase will affect engine cooling and propeller performanceAvoid locating outboard centerlines within in(76 mm) of bottom strakes on dual-outboard installations
Use 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