It's an old lifeboat of some form by the looks of it. Either that or a crew boat, for getting workers on and off a drilling platform or island.
The mostly enclosed deck with small portholes is quirk of lifeboat design generally.
Google it, I'm sure someone has had the same thought previously.
Ted 'n' Laurie, plus Jackson (aka Deputy Dog, the Parson Russell Terrier 'fur kid') and, Rylie (who crossed the Rainbow Bridge June 14, 2012).