Why were lightships invented and where were they first used?

 title: 'THE BEACON FIRE.'

Lightships were invented because there are many parts of coasts that are unsuitable for lighthouse construction[253].

Robert Hamblin and David Avery combined resources to establish a floating light at The Nore, and subsequently levied a toll for its maintenance[254]. It was first used at The Nore, according to The Lighthouses and Lightships document[254].