Columbia built four very different 31 footers. The first was constucted in the mid to late 1960''s and was a coastal cruising boat, the second and third used the same hull and were the 5.5 and the Sabre and was a very strange boat. The last was called the 9.6 was constructed from the mid 1970''s through the 1980''s.
The 1960''s 31 is generally ascribed as a Charlie Morgan design. (Although I have seen it ascribed to Crealock) In the 1960''s Columbia was very much a ''value oriented'' boat in much the same way as Catalinas or Hunters are today. They were simple and inexpensive, and not terribly highly regarded in their day.
That said the 31 was a pretty nice boat. They sailed pretty well and had a simple but workable interior layout. Charlie Morgan designed a number of nice boats in this general size range. Most were derived from Charlie Morgan''s successful race boat, ''Paper Tiger'' which was a moderately beamy keel centerboard boat. I beleive that the 31 was offered in both fixed keel and keel/centerboard configurations. By today''s standards, with PHRF ratings between the mid 230 to low 250 range) these are very slow boats for a 31 footer. Still they sail well and do not have some of the bad habits of other boats of this era.
35 to 40 years ago, when these boats were being built, they were considered to have pretty mediocre build quality. After nearly 40 years I would be very careful buying one of these boats. You need to have an extremely careful survey. If not carefully maintained and upgraded these boats are likely to be a real project to put into safe workable condition costing far more than the boat can ever be worth.
The second pair of 31''s (Sabre and 5.5 meter) are an interesting footnote in history. The 5.5 meters were a development class that were raced in the Olympics. The class rules required that the boats be of wooden construction. In the mid 1960''s the Olympic Sanction Bodies were concerned that 5.5 meters were too expensive thereby eliminating too many nations from racing in this class.
In response the 5.5 meter class proposed allowing fiberglass construction. Columbia tooled up a fiberglass 5.5 meter in anticipation of the 5.5 meter class approving fiberglass constuction, but when the 5.5 meter class association met, they decided to not to approve glass construction and the IYRU and the Olympic Sanctioning committee chose to use Solings instead as the Olympic Keelboat class.
Meanwhile, Columbia was stuck with the tooling for a race boat that could not be raced. A number of 5.5 were built and used as daysailors and one design racers but not very many. Columbia in desperation added a cruising deck house and a very cramped interior and sold these boats as the ''Sabre''. Sabres are interesting looking boats, long, low and narrow with long overhangs. They are really an interesting pice of history that would make an interesting daysailor in an area with pretty steady winds in the low teens and minimal chop.
The last 31 was the Alain Payne designed 9.6. The 9.6 was part of a series that that Columbia called their ''wide bodies''. The 9.6 in poarticular was most close in their hull and rig design to Payne''s IOR race boats of that era. These were beamier than earlier Columbias boats and had the pinched in ends of early 1970''s IOR boats. I raced on one of these when it was a nearly new boat. I thought they only sailed so so and reflected many of the sailing characteristics that made IOR boats notorious. They had reasonably good upwind performance but they tended to be quite rolly off the wind and had a pretty uncomfortable motion. They were pretty poor boats in a chop. They were quite slow reaching and running. This was one of the first, if not the first, boats that I sailed on with a mid- boom cabin top mounted main sheet and at least on the boat I sailed it worked very poorly.
Build quality was not the best. It was very odd about these boats, Columbia was in a state of change. They were trying to present an image of a quality boat builder and some details reflected some nicer quality decisions (such as teake veneer plywood instead of the earlier formica covered plywood), but when you got into the details there were a lot of corners cut. For example, the one that I raced on had way undersized winches for the headsails. She had problems with her bulkhead tabbing which had let loose in places allegedly while being trucked to Georgia from California.
That''s about it.