DETECTING LATERAL MOTION
It is second nature for an experienced mariner, who lives and works closely with the elements than perhaps any other professional, to make allowances for wind and current. It is equally important that the shiphandler also develop an appreciation for the less obvious lateral motion that results from
1. Turning as the ship is approaching the berth.
2. Extended use of tugs.
3. Checking or holding the lines before the ship is alongside.
These actions cause sideward motion independent of any motion caused by the wind and current, even when the ship is making no headway. If not checked, the ship moves laterally toward or away from the berth or comes alongside with excessive force. Lateral motion may be desirable at times and is not so much an effect to be avoided as a factor to be watched for and used to advantage.
Lateral motion is easier to detect when working from the centerline of the ship because you have a better view of the vessel and her heading. Watch objects ashore located ahead or astern, Use their change in alignment as a range to detect lateral motion, and note when the distance from the pier increases or decreases independent of heading, wind, and current.
The ability to detect this sideward slide through the water and make use of it, is a mark of an accomplished shiphandler because it is one of the effects that is least appreciated by an inexperienced pilot or master.
