In the early '60s, Columbia published a newsletter. Volume 1, No. 3 is dated Fall/Winter 1965. In it is an announcement of new models. I am familiar with the C-34 and the C-50 mentioned, but there are a few other models that I had never heard of before. They are:
I also have a copy of an early ad for a C-24. At the bottom of the page is the familiar row of Columbia shields, one for each model. At the far right are shields for a 30, a 35, and a 40 - power yachts.
Could this be a 1964 C-30 power yacht?
Check here for more information on Columbia's Power Yachts
What I have listed above is all I know about any of these models.