That's a Clyde Puffer designed by Simon Richardson. These small coasters used to carry essential supplies (like whisky) around the highlands and islands of Scotland.
They were immortalised by the author Neil Munro in "Para Handy tales" a very famous book in Scotland detailing the voyages of the SS Vital Spark. The book was the inspiration for the Ealing comedy "the Maggie", a fantastic 1960's and 70's BBC TV sitcom "The Vital Spark" and another TV series "Tales of Para Handy" in the 1990's.
Hopefully at some point she will become playable at some point and V-Step can make the Firth of Clyde area to sail her in, that would be "chust sublime" as Para would say.
You can find out more about puffers here (http://en.wikipedia.org/wiki/Clyde_puffer)