Mercury 300 XS OptiMax Manual page 120

MOUNTING HEIGHT - FLEET MASTER GEARCASE
Improper installation of an outboard can result in serious injury or death. Do
not allow the upper outboard mounting bolts to be closer than 25 mm (1 in.)
from the top of the boat transom, not including any shims used to increase
transom mouting height. Never install the upper mounting bolts through these
shims.
Install the outboard to a height so that the distance between the underside of
transom bracket hooks and the bottom of the boat (measurement "c" in the
diagram below) falls between the recommended mounting height range.
Ensure that this measurement is to the actual bottom of the boat, not to any
steps or notches in the hull.
IMPORTANT: The recommended mounting height is based on performance
testing with single‑engine applications on hulls with no stepped or notched
transoms. Your results may vary, depending on hull design.
c
722.6 mm
(28.45 in.)
a - Underside of transom bracket hooks
b - Bottom of the boat
c - Distance between "a" and "b"
d - Propeller shaft centerline
OUTBOARD INSTALLATION
WARNING
!
114
a
b
d
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