The Southern Cross 39 is a double-ender following the theme of her two smaller siblings the Southern Cross 31 and Southern Cross 35. Designed by Thomas Gillmer, a professor of naval architecture at the US Naval Academy. The SC39 has the same canoe stern and sharply rising sheer line. She has a modified fin keel and skeg hung rudder arrangement. Her cutter rig with bowsprit has 774 sq. ft. of canvas and a displacement of 21,000 lbs.

Launched in 1981, the first 13 hulls were factory built, others were built as kits and some of the non factory finished boats are called Gillmer. This designation was added at a later date, somewhere around 1985, to distinguish between factory finished and owner completed. 

The most common configuration has a V-berth forward, quarter berth portside, and a u-shaped galley amidships providing a three cabin type layout. Some of the mid ship bullheads were reconfigured for these layouts. 

The hulls were built in fiberglass with Airex foam coring throughout while the deck and cabin house were balsa cored. The ballast is internally set (lead in most cases. Water tanks are set in the keel while the fuel tank is underneath the aft berth.

Design changes moved the prop to an aperture in the rudder. The first hulls had the VDrive and an exposed prop.  

These boats were built until 1990 when the Ryder factory closed in Bristol RI.