Probably from the same mold as the COLUMBIA 28. At this time both Columbia and Coronado were divisions of Whittaker Corp.

In 1966 Offshore Yachts aquired the molds and renamed the boat the HALCYON 27. See HALCYON 27.
Shown here is the DIAMOND MKII. An earlier version had a fractional rig.

Based on the earlier DIAMOND 27 built by Thames Marine Ltd.(UK).

A keel centerboard version was also available.
Draft (max.): 4.50′ / 1.37m Draft (min.): 2.50′ / 0.76m
Displacement: 4300 lbs./ 1950 kgs. Ballast: 1800 lbs. / 816 kgs.

It’s likely that this design is based on the earlier BLUE WATER 24.

Hull #1 for this boat is listed as having been completed in 1965. It appears that, from the beginning, it was called the SPENCER 42-2. If there was in fact an earlier version, how it may have differed from the one shown here is unknown. A number have been completed as kits. The boats that were completed at the factory were usually customized to the original customers requirements. Listed dimensions are from a builder’s brochure but can vary.
A sloop rig was standard. Cutter rig optional.
Also available as an optional ketch. Sail area: 778 sqft

Built from the modified hull mold of the SPENCER 42. Most had more freeboard to acommodate a center cockpit layout but details differ from one boat to another. Sloop or ketch rig.

Shoal draft: 4.67′.