The Calshot Spit Light Float seen in this image sits in the Solent Southampton marking the Calshot Spit pebble bank that poses a danger to shipping in-bound or out-bound for the Port of Southampton. I did not know until I did an Internet search that the catamaran floats allow the light to always align with the tide aiding Pilots navigate the Thorn (deep water) channel and the sharp turn into Southampton Water. There is a wealth of information on the Internet about the Calshot Light Float and about the history of Calshot Spit itself.