This was an unusual build project for Parkol, a Foyboat is a small vessel primarily used to assist the mooring and servicing of a larger vessel. It is not a Tug per se. The word has often been associated with the rivers of North East England.
Foyboat's etymology directly ties this dialect word to a workboat of the River Tyne (and also the Wear and Tees) used to assist larger vessels, the term is known to have been used elsewhere in Britain. Around Ramsgate and Margate are a couple of examples & the presence of anchored vessels in The Downs would explain the need for such service
