Boat lift
A boat lift, ship lift, or lift lock is a machine for transporting boats between water at two different elevations, and is an alternative to the canal lock and the canal inclined plane.
http://en.wikipedia.org/wiki/Boat_lift
A boat lift, ship lift, or lift lock is a machine for transporting boats between water at two different elevations, and is an alternative to the canal lock and the canal inclined plane.
http://en.wikipedia.org/wiki/Boat_lift