Federation vessels used as private colony transports. They are about four times larger than the Danube-class runabout.

The Erewhon has been spelled as Erewon in the Star Trek Encyclopedia. The registry BDR-529 is the license plate number in the movie "Blues Brothers." The Erewhon itself is also another joke, switch the 'w' and 'h', then spell it backwards.

SS Santa Maria BDR-529
   Crash landed on planet in Orelious Minor system while on a mission to Gemulon V in 2360.
   Named for Christopher Columbus' ship used to travel to the Americas.
   "Paradise" - DS9.