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Triangle 20
Designer: Charles Angle  ·  Builder: Triangle Marine Co./Grampian Marine Ltd.  ·  First built: 1961
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About the Triangle 20

Designed by Charles Angle and produced during a brief but notable three-year run from 1961 to 1963, this compact fractional sloop represents an interesting chapter in early fiberglass sailboat development. With only 75 hulls built by Triangle Marine Co. and later Grampian Marine Ltd., the Triangle 20 has become something of a rare find in today's used boat market. The boat's proportions reveal a design focused on coastal sailing and daysailing adventures. Her generous beam of just over seven feet provides surprising interior volume for a 20-footer, while the substantial displacement of 2,300 pounds suggests solid construction and seakindly handling characteristics. The keel/centerboard configuration offers versatility for both deeper waters and shoal exploration, making her well-suited for varied cruising grounds. Performance-wise, the Triangle 20 strikes a balance between comfort and capability. Her comfort ratio of 14.7 indicates relatively quick motion in a seaway, typical of smaller boats, while the capsize screening value suggests reasonable stability for coastal conditions. The fractional rig with 205 square feet of sail area should provide adequate power in light to moderate conditions, though heavy-weather performance would naturally be limited by her size. This vintage design appeals most to sailors seeking an affordable entry into classic fiberglass boats with character.

Core Dimensions
LOA (Length Overall) 20.50 ft / 6.25 m
LWL (Waterline Length) 16.67 ft / 5.08 m
Beam 7.08 ft / 2.16 m
Max Draft 4.75 ft / 1.45 m
Min Draft 2.17 ft / 0.66 m
Displacement 2,300.00 lb / 1,043 kg
Sail Area (Reported) 205.00 ft² / 19.05 m²
Design & Construction
Hull Type Keel/Cbrd.
Rigging Type Fractional Sloop
Construction FG
Designer Charles Angle
Builder Triangle Marine Co./Grampian Marine Ltd.
First Built 1961
Last Built 1963
Number Built 75
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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
18.87
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
221.65
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
14.7
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
2.15
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. 5.47 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. 421.71 pounds/inch
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