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Thompson 27
Designer: Guy Thompson  ·  Builder: Uk  ·  First built: 1971
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About the Thompson 27

Designed by Guy Thompson and first launched in 1971, this British-built 27-footer represents classic early-1970s sailing design philosophy with its traditional fin keel configuration and masthead sloop rig. The fiberglass construction delivers durability while maintaining the refined lines characteristic of Thompson's work during this era. With a displacement of 6,100 pounds and substantial ballast of 2,767 pounds, this boat offers reassuring stability for coastal cruising and weekend adventures. The generous beam of 8 feet provides comfortable interior space despite the compact 26.67-foot overall length, while the moderate 5.67-foot draft allows access to a variety of harbors and anchorages. The Thompson 27's comfort ratio of 25.62 indicates a relatively stiff, performance-oriented design that favors sailing efficiency over pure comfort, making it well-suited for sailors who enjoy spirited sailing in moderate conditions. The capsize screening formula of 1.75 suggests good stability characteristics for coastal and near-shore sailing, though extended offshore passages would require careful weather planning. Built during an era when British boatbuilding was renowned for solid construction and practical design, the Thompson 27 appeals to sailors seeking a manageable boat that doesn't sacrifice sailing performance for size.

Core Dimensions
LOA (Length Overall) 26.67 ft / 8.13 m
LWL (Waterline Length) 21.50 ft / 6.55 m
Beam 8.00 ft / 2.44 m
Max Draft 5.67 ft / 1.73 m
Displacement 6,100.00 lb / 2,767 kg
Ballast 2,767.00 lb / 1,255 kg
Design & Construction
Hull Type Fin Keel
Rigging Type Masthead Sloop
Construction FG
Designer Guy Thompson
Builder UK
First Built 1971
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Performance Ratios
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
45.36
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
274.01
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
25.62
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
1.75
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. 6.21 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. 614.57 pounds/inch
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