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Cape 31
Designer: Mark Mills  ·  Builder: Cape Performance Sailing (South Africa)  ·  First built: 2017
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About the Cape 31

Designed by Mark Mills and launched in 2017, this South African-built performance cruiser represents a modern approach to coastal sailing with serious offshore potential. Cape Performance Sailing created the Cape 31 as a lightweight, responsive yacht that bridges the gap between pure racing machines and comfortable cruisers. The fin keel with bulb configuration and spade rudder deliver exceptional maneuverability and upwind performance, while the fractional sloop rig provides versatility across varying wind conditions. With a displacement of just 3,902 pounds and a substantial sail area of 534 square feet, the boat achieves an impressive sail area to displacement ratio of 34.57, indicating spirited performance in light to moderate winds. The relatively deep draft of 8.04 feet contributes to stability and tracking ability, making this yacht well-suited for coastal cruising and club racing. The comfort ratio of 9.25 suggests a motion that favors performance over pure comfort, typical of modern sport cruisers. Despite its performance orientation, the GRP construction and 15-horsepower auxiliary engine make it practical for extended coastal passages. This yacht appeals to sailors seeking a responsive, well-built boat capable of weekend racing while remaining comfortable enough for coastal cruising adventures.

Core Dimensions
LOA (Length Overall) 31.36 ft / 9.56 m
LWL (Waterline Length) 28.97 ft / 8.83 m
Beam 10.17 ft / 3.10 m
Max Draft 8.04 ft / 2.45 m
Displacement 3,902.18 lb / 1,770 kg
Ballast 1,565.28 lb / 710 kg
Ballast Type Carbon fin with lead bulb
Sail Area (Reported) 534.00 ft² / 49.61 m²
Design & Construction
Hull Type Fin w/bulb & spade rudder
Rigging Type Fractional Sloop
Construction GRP
Designer Mark Mills
Builder Cape Performance Sailing (South Africa)
First Built 2017
Associations Cape 31 Class Association
Related Sailboats ["J97" · "First 317 Beneteau" · "Sun Fast 31 Jeanneau" · "Northshore 310" · "Hansson 31"]
Owner Reviews

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Performance Ratios
PHRF Rating PHRF (Performance Handicap Racing Fleet) is a national racing handicap measured in seconds per nautical mile. Lower values indicate faster boats. Ratings are sourced from US Sailing's national database (median across 60+ regional fleets).
Under 0 — Ultralight racer0–90 — Performance racer90–150 — Cruiser/racer150–210 — Typical cruiserOver 210 — Heavy/slow cruiser
 20
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
 34.57
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
 40.11
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
 71.65
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
 9.25
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
 2.59
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. 7.21 kn
S# (Speed Number) The Speed Number (S#) is a quick performance index. Higher values indicate a faster, more powerful design relative to its size.
Under 3.0 — Slow cruiser3.0–5.0 — Average cruiser5.0–7.0 — Performance cruiserOver 7.0 — Racer
 7.66
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. 1,052.73 pounds/inch
SA/Displacement (Calc) Calculated Sail Area to Displacement ratio using actual measured sail dimensions rather than reported values. More precise than the reported SA/Disp figure. 34.57
Rig Dimensions
I (Foretriangle Height) 40.88 ft / 12.46 m
J (Foretriangle Base) 11.81 ft / 3.60 m
P (Mainsail Luff) 41.01 ft / 12.50 m
E (Mainsail Foot) 14.27 ft / 4.35 m
SA Fore 241.40 ft² / 22.43 m²
SA Main 292.61 ft² / 27.18 m²
SA Total (100%) 534.01 ft² / 49.61 m²
Est. Forestay Length 42.55 ft / 12.97 m
Engine & Accommodations
Engine Make Yanmar
Engine Model 2YM
Engine Type Diesel; Saildrive
Horsepower 15
How It Compares

vs. First 317 Beneteau, Northshore 310, Sun Fast 31 Jeanneau

This boat Similar boats
Dimensions
LOA
Cape 31 ★
31.4 ft
First 317 Beneteau
31.5 ft
Northshore 310
31.2 ft
Sun Fast 31 Jeanneau
31.2 ft
LWL
Cape 31 ★
29.0 ft
First 317 Beneteau
28.9 ft
Northshore 310
28.1 ft
Sun Fast 31 Jeanneau
27.2 ft
Beam
Cape 31 ★
10.2 ft
First 317 Beneteau
10.6 ft
Northshore 310
10.0 ft
Sun Fast 31 Jeanneau
10.8 ft
Displacement
Cape 31 ★
3 lbs
First 317 Beneteau
8 lbs
Northshore 310
7 lbs
Sun Fast 31 Jeanneau
8 lbs
Ballast
Cape 31 ★
1 lbs
First 317 Beneteau
2 lbs
Northshore 310
3 lbs
Sun Fast 31 Jeanneau
3 lbs
Sail Area
Cape 31 ★
534 sq ft
First 317 Beneteau
—
Northshore 310
502 sq ft
Sun Fast 31 Jeanneau
506 sq ft
Performance
SA / Displacement (higher = more powerful)
Cape 31 ★
34.6
First 317 Beneteau
—
Northshore 310
21.7
Sun Fast 31 Jeanneau
20.0
Ballast / Disp (higher = stiffer)
Cape 31 ★
40.1 %
First 317 Beneteau
27.3 %
Northshore 310
—
Sun Fast 31 Jeanneau
40.5 %
Comfort Ratio (higher = more comfortable offshore)
Cape 31 ★
9.3
First 317 Beneteau
—
Northshore 310
17.9
Sun Fast 31 Jeanneau
—
Capsize Screening (lower = safer)
Cape 31 ★
2.59
First 317 Beneteau
—
Northshore 310
2.07
Sun Fast 31 Jeanneau
—
Displacement / Length (lower = lighter)
Cape 31 ★
71
First 317 Beneteau
153
Northshore 310
—
Sun Fast 31 Jeanneau
180
Hull Speed
Cape 31 ★
7.2 kts
First 317 Beneteau
—
Northshore 310
7.1 kts
Sun Fast 31 Jeanneau
—
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