Historians have dispelled a rumour that the Royal Navy once launched a ship called HMS Friday to encourage sailors to set sail on that day.
According to the myth, the Royal Navy launched HMS Friday on a Friday and put a Captain James Friday in command before it myseriously disappeared.
But Portsmouth's Royal Navy Museum said no HMS Friday had ever existed.
The museum's Julian Thomas said the story "regularly arose", particularly around a superstitious Friday the 13th.
'Sailors are superstitious'
He added there was "absolutely no truth to the tale which has many internet references".
"Presumably, it has surfaced because of it being Friday the 13th this week and there are dozens of references to it on the internet," said Mr Thomas.
"Sailors certainly are superstitious - it's something to do with being at the mercy of such an unpredictable element as the sea - and anyway who would want to give up a weekend ashore.
"But we can confirm that there has never been a Royal Navy ship named HMS Friday - or after any other day of the week for that matter."