Mercury 40 4-Stroke Manual page 76

INSTALLATION SPECIFICATIONS
a - Minimum transom opening
Minimum Transom Opening
Single engine (remote)
Single engine (tiller)
Dual engines
Engine Centerline
Minimum
LIFTING OUTBOARD
Use the lifting eye on the engine.
OUTBOARD INSTALLATION
A
A
b - Engine centerline for dual engines
48.3 cm (19 in.)
76.2 cm (30 in.)
101.6 cm (40 in.)
66 cm (26 in.)
28510
70
B
2763