Generally, it's not such a good idea to leave the motor on the boat when
trailering because the motor's mounting system is not designed to cope with
road bounce when in the raised position. This is quite apart from the
stresses put on the hull. Add that to the risk of theft and so I don't do it.
The MERCURY Outboard manual specifically warns against using the full tilt up
position when trailering. I came across an owner who had left the o/b on the
boat. getting the motor to tilt to the working position was a workshop job
because of a bent tilt support pin.
Bruce Longstaff
Uxbridge GB