Hello Mojo47,
From your post, I'm guessing that you got your vessel names from the CLIP (Crew List Indexing Project) crew lists at FindMyPast. You need to go back there and get a more important piece of information for each of them - the Official Number - sometimes written as ON, O. N. or O/N.
The O/N is a unique and permanent identifier for a vessel, remaining constant throughout changes of ownership, changes of registry and changes of name. It is invaluable in distinguishing between multiple vessels of the same name.
I can't do it for you because I don't have a sub.
Please also tell us John Davy's rank/s aboard each and any numbers that may be written in beside his name (could be register ticket number or certificate number, both useful leads to further information).
Have you also looked for him in the merchant navy records at Ancestry? They have ones different to FindMyPast's offerings.
If the crew list for FISHER includes the O/N for SIGNUS, so much the better. You can take that to the CLIP website ......
http://www.crewlist.org.uk/data/vesselsnum.php... and feed it into the "Ships by Official Number" search box to find out if the name has indeed been phonetically mispelt and should be CYGNUS.
Cheers,
Westoe
