The Mariah 27 is an American sailboat that was designed by Graham & Schlageter as a Midget Ocean Racing Club (MORC) racer and first built in 1986.
The design is very similar to the G&S 27, which was designed the same year by Graham & Schlageter.
The Mariah 27 is a racing keelboat, built predominantly of fiberglass. It has a masthead sloop rig, an internally mounted spade-type rudder controlled by a tiller and a fixed fin keel. It displaces and carries of ballast.
The boat has a draft of with the standard keel. The boat is normally fitted with a small outboard motor for docking and maneuvering.
The design has a hull speed of .