Honda BF9.9A Owner's Manual page 28

To avoid damaging the motor, use the utmost care when mooring a
boat, especially when its motor is tilted up. Don't allow the motor to
strike against the pier or other boats.
Trailering
When trailering or transporting the boat with the motor attached, it is
recommended that the motor remain in normal running position with
the steering friction bolt tightened securely.
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Do not trailer or transport the boat with the motor in the tilted
position. The boat or motor could be severely damaged if the motor
drops.
The motor should be trailered in the normal running position. If there
is insufficient road clearance in this position, then trailer the motor in
the tilted position using a motor support device such as a transom
saver bar, or remove the motor from the boat. Tilt lever should be in
the tilt position.
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