Interesting. It's a Bill Tripp design that debuted in 1965. Should be a great sailing
boat and it appears to have been well maintained. Some info, including layout drawings, here:
Columbia 50 Specifications
The Dashews circumnavigated on one, and that's certainly a plus that speaks well of the design and build.
on edit: I just saw Steve Dashew's note at the link. Looks like the only connection to the
Columbia 50 for the Dashew's
boat is the
hull design. Otherwise it was a custom built boat.