Depending on the angle of the ramp, the depth of the water, the design
of the trailer, and the draft of the boat on the trailer you will need
to submerge the trailer to different depths to launch. Often this means
the trailer will be almost completely submerged.

Thanks. This makes sense. The ramp in the boat dealer's place is kind
of flat. This probably explains the reason why the boat dealer needed
to almost fully submerge the trailer in order to launch the boat.

It's important to make sure that your wiring is waterproof
(most people disconnect the brake lights before backing in)
and that your wheel bearings are protected.

Yes, I will make sure I will put this in the check-list of "Pre-Launch
Preparation".

Thanks.

Jay Chan