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Quarter Ton Class
Designer: Various  ·  Builder: Various  ·  First built: 1967
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About the Quarter Ton Class

Developed as part of the International Offshore Rule (IOR) racing series that gained prominence in the late 1960s, Quarter Ton Class sailboats represent a fascinating chapter in competitive sailing history. These 23-foot racers emerged from various designers and builders who interpreted the strict rating requirements differently, resulting in diverse hull forms united by common performance characteristics. With their fin keel and spade rudder configuration, Quarter Tonners exhibit nimble handling and responsive steering that made them formidable competitors on the racing circuit. The relatively light 3,000-pound displacement combined with 270 square feet of sail area creates a spirited sailor capable of impressive performance in moderate conditions. The masthead sloop rig provides versatility for both racing and recreational sailing. While originally conceived for offshore racing under the Quarter Ton Cup rules, these boats translate well to coastal cruising and club racing today. The comfortable 13.74 comfort ratio suggests reasonable motion at sea, though the racing-oriented design prioritizes performance over creature comforts. Modern sailors appreciate their historical significance and engaging sailing characteristics, making them sought-after classics for those wanting to experience the golden age of IOR racing while enjoying weekend adventures on protected waters.

Core Dimensions
LOA (Length Overall) 23.00 ft / 7.01 m
LWL (Waterline Length) 18.00 ft / 5.49 m
Beam 8.50 ft / 2.59 m
Max Draft 4.50 ft / 1.37 m
Displacement 3,000.00 lb / 1,361 kg
Ballast 1,200.00 lb / 544 kg
Sail Area (Reported) 270.00 ft² / 25.08 m²
Design & Construction
Hull Type Fin w/spade rudder
Rigging Type Masthead Sloop
Construction FG
Designer Various
Builder Various
First Built 1967
Related Sailboats ["Sonar" · "Pearson 23" · "Irwin 23" · "North American 23" · "San Juan 23"]
Owner Reviews

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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
 20.82
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
 40
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
 229.64
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
 13.74
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
 2.36
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. 5.69 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. 546.69 pounds/inch
How It Compares

vs. Irwin 23, North American 23, Pearson 23

This boat Similar boats
Dimensions
LOA
Quarter Ton Class ★
23.0 ft
Irwin 23
23.0 ft
North American 23
23.0 ft
Pearson 23
23.0 ft
LWL
Quarter Ton Class ★
18.0 ft
Irwin 23
18.5 ft
North American 23
20.0 ft
Pearson 23
20.0 ft
Beam
Quarter Ton Class ★
8.5 ft
Irwin 23
8.0 ft
North American 23
7.9 ft
Pearson 23
8.0 ft
Displacement
Quarter Ton Class ★
3 lbs
Irwin 23
3 lbs
North American 23
2 lbs
Pearson 23
3 lbs
Ballast
Quarter Ton Class ★
1 lbs
Irwin 23
1 lbs
North American 23
800 lbs
Pearson 23
1 lbs
Sail Area
Quarter Ton Class ★
270 sq ft
Irwin 23
256 sq ft
North American 23
215 sq ft
Pearson 23
238 sq ft
Performance
PHRF Rating (lower = faster)
Quarter Ton Class ★
—
Irwin 23
228 s/nm
North American 23
249 s/nm
Pearson 23
240 s/nm
SA / Displacement (higher = more powerful)
Quarter Ton Class ★
20.8
Irwin 23
18.9
North American 23
17.4
Pearson 23
16.6
Ballast / Disp (higher = stiffer)
Quarter Ton Class ★
40.0 %
Irwin 23
—
North American 23
28.6 %
Pearson 23
37.1 %
Comfort Ratio (higher = more comfortable offshore)
Quarter Ton Class ★
13.7
Irwin 23
15.6
North American 23
13.2
Pearson 23
16.3
Capsize Screening (lower = safer)
Quarter Ton Class ★
2.36
Irwin 23
2.17
North American 23
2.25
Pearson 23
2.11
Displacement / Length (lower = lighter)
Quarter Ton Class ★
229
Irwin 23
—
North American 23
156
Pearson 23
195
Hull Speed
Quarter Ton Class ★
5.7 kts
Irwin 23
5.8 kts
North American 23
6.0 kts
Pearson 23
6.0 kts
Speed Number (higher = faster)
Quarter Ton Class ★
—
Irwin 23
2.7
North American 23
3.3
Pearson 23
2.6
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