In the days when light vessels were still found in tight waters frequented by ships heading up for ports, the pilots used the way they were lying to tell at a glance how the tide was setting. When the Calshot Lightship in the central Solent came up for replacement, a compromise was reached. Today, the light float that replaced the old ship carries an anchor ball on the side to which the mooring is attached – ie, the up-tide side.
Sadly, by no means all light floats have done the same, but a good number follow the example of the Roaring Middle safe water mark in the Wash. While not a fully fledged lightship, the tower part of this important mark is mounted on a small boat with a defined bow and stern. She lies to the tide as sweetly as any of our yachts.
