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Sound One Design
Designer: Sparkman & Stephens  ·  Builder: Sound Marine Construction Co. (Usa)  ·  First built: 1949
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About the Sound One Design

Designed by the legendary Sparkman & Stephens firm in 1949, this classic 31-foot sailboat represents mid-century American yacht design at its finest. Built by Sound Marine Construction Co. with traditional wood construction, the Sound One Design embodies the craftsmanship and attention to detail that defined the post-war sailing renaissance. With her moderate displacement of 9,472 pounds and substantial ballast ratio, this fractional sloop offers excellent stability and seakeeping abilities for coastal cruising and weekend adventures. The 23-foot waterline length provides efficient sailing performance, while the comfortable 30.87 comfort ratio indicates she'll provide a pleasant motion in choppy conditions. Her conservative capsize screening value of 1.7 suggests good stability characteristics for protected waters and near-shore sailing. The keel/centerboard configuration offers versatility for exploring both deeper waters and shallow gunkholes, making her particularly well-suited for cruising areas like Long Island Sound, the Chesapeake, or similar protected coastal regions. Her fractional rig with 469 square feet of sail area provides balanced performance without being overpowering for a small crew. This design represents classic American sailing at its most refined, perfect for sailors seeking traditional character with proven seaworthiness.

Core Dimensions
LOA (Length Overall) 31.00 ft / 9.45 m
LWL (Waterline Length) 23.00 ft / 7.01 m
Beam 9.00 ft / 2.74 m
Max Draft 3.00 ft / 0.91 m
Displacement 9,472.00 lb / 4,296 kg
Ballast 3,140.00 lb / 1,424 kg
Ballast Type Lead
Sail Area (Reported) 469.00 ft² / 43.57 m²
Design & Construction
Hull Type Keel/Cbrd.
Rigging Type Fractional Sloop
Construction Wood
Designer Sparkman & Stephens
Builder Sound Marine Construction Co. (USA)
First Built 1949
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Performance Ratios
SA/Displacement Sail Area to Displacement ratio measures how much sail power a boat has relative to its weight. Higher values mean more performance and speed.
Under 14 — Heavy cruiser, slow14–18 — Cruising sailboat18–22 — Cruiser/racerOver 22 — Performance racer
 16.82
Ballast/Displacement Ballast to Displacement ratio shows what percentage of the boat's total weight is ballast. Higher values generally mean better initial stability and stiffer sail carrying.
30–35% — Typical cruiser35–45% — Stiff performance boatOver 45% — Racing oriented
 33.15
Displacement/Length Displacement to Length ratio measures how heavy a boat is relative to its waterline length. Lower values mean a lighter, faster boat.
Under 100 — Ultralight racer100–200 — Light cruiser/racer200–300 — Moderate cruiser300–400 — Heavy cruiserOver 400 — Very heavy
 347.54
Comfort Ratio Ted Brewer's Comfort Ratio predicts how comfortable a boat will feel in offshore conditions. Higher values mean a steadier, more comfortable motion in a seaway.
Under 20 — Uncomfortably rough20–30 — Acceptable coastal30–40 — Good offshore comfortOver 40 — Very comfortable offshore
 30.87
Capsize Screening Formula The USHS Capsize Screening Formula estimates offshore capsize risk. Lower is safer — values under 2.0 are considered acceptable for offshore sailing.
Under 2.0 — Safe for offshore2.0–2.2 — Borderline offshoreOver 2.2 — Coastal use recommended
 1.7
Hull Speed Hull Speed is the theoretical maximum speed of a displacement hull, calculated from waterline length. Most cruising sailboats reach this speed in moderate conditions. 6.43 kn
Pounds/Inch Immersion Pounds per Inch Immersion (PPI) tells you how much weight is needed to sink the boat one inch. Useful for calculating how additional gear and stores affect waterline. 739.63 pounds/inch
Engine & Accommodations
Engine Make Gray
Engine Model 4-91
Engine Type Gas
Fuel Capacity 23 gals / 87 L
Water Capacity 20 gals / 76 L
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