Design and Construction
The Atlanta 31 draws between 4.0 and 4.3 feet depending on load, riding a long keel of iron with 4,480 pounds of ballast against a 15,680-pound displacement. Her length-to-beam ratio of 3.20 and displacement-length ratio of 319 place her among heavy cruisers, while a motion comfort ratio of 40.5 suggests a damped, steady motion. The wetted bottom surface runs about 290 square feet, and the immersion rate of 944 pounds per inch shows how reluctantly she changes trim as loaded.
Rig and Handling
As a ketch, the Atlanta 31 carries 360 square feet of sail area, and the sail-area-to-displacement ratio of 9.20 confirms she is built to carry rather than sprint. Her capsize screening value of 1.55 is conservative for her length. The theoretical hull speed of 7.1 knots is the displacement limit for her waterline. Listed sheet diameters are 12 mm for jib, genoa, mainsheet, and spinnaker. The ketch with long keel favors manageable offshore sail splits.
Accommodations
The heavy displacement and 9-foot-8 beam imply volume traded for ballast security. The Atlanta 31 was produced in owner and charter configurations, the latter more often seen resale. Colvic's practice of selling hulls unfinished means interiors vary widely.
Known Issues
The sensitivity to loading from the 944 pounds-per-inch immersion rate means an overloaded Atlanta 31 loses freeboard and helm balance as her draft grows from 4.0 to 4.3 feet. Treat ballast ratio and immersion as a hard load ceiling.
Refits and Ownership
Colvic sold many hulls as bare or part-finished shells, so systems reflect the assembler. The iron keel needs rust vigilance; the long keel makes inspection straightforward.
The Verdict
The Atlanta 31 is a stable, well-ballasted ketch rigged for offshore cruising, not speed.
Pros
- Conservative capsize screening value of 1.55 and 29 percent ballast ratio
- Heavy-cruiser displacement-length ratio of 319 for steady motion
- Solid fibreglass hull with straightforward iron long keel
Cons
- Modest sail area for her weight limits light-air performance
- Immersion rate of 944 lbs/inch penalizes overloading heavily
- Varying completion quality from Colvic's kit-built sales model
