Vessel can not be regarded as particle while vessel is berthing, so distance of vessel and shoreline is not distance of point and line, it should be calculated as space between polygon and line.

The parallel approaching method based on position signals of the line of sight (LOS) is often used in control of approaching phase of the space rendezvous and berthing.

If the ship can safely berthing, must ensure that the parallel berthing, maintenance of ship and the pier parallel to the line end to end.