Design and Construction
The Atlanta 31 displaces 15,680 pounds and carries 4,480 pounds of ballast, giving her a ballast ratio of 29 percent. Draft varies from 4.0 to 4.3 feet depending on load.
Her length-to-beam ratio of 3.20 and displacement-length ratio of 319 place her among heavy cruisers. A motion comfort ratio of 40.5 suggests a damped, steady motion. The wetted bottom surface is about 290 square feet.
An immersion rate of 944 pounds per inch indicates that she changes trim reluctantly as weight comes aboard. However, as loading increases and draft grows from 4.0 to 4.3 feet, she loses freeboard and helm balance. Ballast ratio and immersion should therefore be treated as a hard load ceiling.
Rig and Handling
The ketch rig carries 360 square feet of sail. A sail-area-to-displacement ratio of 9.20 confirms that the Atlanta 31 is built to carry rather than sprint, and her modest sail area limits light-air performance.
The ketch rig and long keel favor manageable offshore sail splits. Her capsize screening value of 1.55 is conservative for a boat of this length, while the theoretical hull speed of 7.1 knots marks the displacement limit for her waterline.
Listed sheet diameters are 12 mm for the jib, genoa, mainsheet, and spinnaker.
Accommodations
The Atlanta 31’s heavy displacement and 9-foot-8 beam imply volume traded for ballast security. She was produced in owner and charter configurations, with charter versions appearing more often on the resale market.
Colvic sold many boats as bare hulls or part-finished shells, so interiors and onboard systems vary widely according to the assembler.
Refit and Ownership Considerations
Completion quality can vary because of Colvic’s kit-built sales model. Systems likewise reflect whoever assembled and finished each boat.
The iron keel requires vigilance for rust; the long keel makes inspection straightforward.
The Verdict
The Atlanta 31 is a stable, well-ballasted ketch rigged for offshore cruising rather than speed.
Pros
- Conservative capsize screening value of 1.55 and a 29 percent ballast ratio
- Heavy-cruiser displacement-length ratio of 319, contributing to steady motion
- Solid fibreglass hull and straightforward iron long keel
Cons
- Modest sail area for her weight limits light-air performance
- An immersion rate of 944 lbs/inch heavily penalizes overloading
- Completion quality varies because of Colvic’s kit-built sales model
