Two 50 - foot ( 15 m ) long versions were built as the first of a proposed fleet of Thames - class lifeboats .
The class was cancelled in favour of an Arun class with a different hull shape and improved crew facilities .
Two 50 - foot ( 15 m ) long versions were built as the first of a proposed fleet of Thames - class lifeboats but the class was cancelled in favour of an Arun class with a different hull shape and improved crew facilities .