Design and Construction
Northshore built the Southerly 100 in fiberglass with an iron swing keel, and the hull is a solid laminate rather than a cored layup hull of solid fiberglass construction. The keel itself is iron, and the boat draws between roughly 2.26 and 2.56 feet depending on load, which lets her tuck into shallow marinas that deeper fixed-keel boats cannot reach shallow draft under load. Her length-to-beam ratio is 3.20 against a beam of 10 feet 3 inches, and the ballast ratio sits at 47 percent on a displacement of 9,950 pounds. The wetted surface is about 322 square feet, and the immersion rate of 1,115 pounds per inch tells you how little she settles for a given load — a useful number when you consider provisioning for extended cruising.
Rig and Handling
The 100 is a masthead sloop carrying 509 square feet of sail area, returning a sail-area-to-displacement ratio of 17.30 — modest, and in keeping with a heavy-displacement cruiser rather than a light-air rocket modest sail-power-to-weight figure. The capsize screening value is 1.89, a formula-derived index that places her in the range accepted for offshore-capable cruisers of her type. With a comfort ratio near 25 and a displacement-length ratio above 284, the design reads as a steady, predictable sea boat rather than a featherweight racer, and the variable draft lets the owner trade a 5-foot-10-inch keel-down profile for the shallow-draft mode when coast-hopping or gunkholing.
Accommodations
The boat is equipped with six berths, laid out for a small cruising crew or a family aboard. The fixed keel trunk and the swing-keel machinery occupy space that in a conventional fin-keel 34-footer would be free floor area, but the trade is the draft flexibility noted above.
The Verdict
The Southerly 100 is a purpose-built variable-draft cruiser from Northshore's Carter-era design partnership, offering genuine shallow-water access with an iron swing keel and a ballast ratio that supports stable, comfortable motion when the keel is down. Her modest sail plan and heavy displacement suit relaxed coastal and inland-water cruising more than spirited upwind work, and the 96-boat production run makes her a recognizable if not ubiquitous name in the Southerly story.
Pros
- Swing keel draws as little as 2.26 ft loaded, opening shallow marinas
- Solid fiberglass hull with iron keel and 47% ballast ratio
- Capsize screening value of 1.89; steady heavy-displacement cruiser
Cons
- Sail-area/displacement of 17.30 limits light-air performance
- Only documented accommodation figure is the six-berth count
