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Adams 21
Designer: Adams  ·  Builder: Jarkan Yachts (Au)  ·  First built: 1977
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About the Adams 21

Originally launched in 1977 by Australian builder Jarkan Yachts, this compact fractional sloop represents a thoughtful approach to small boat design from the Adams drawing board. With its fiberglass construction and keel-centerboard configuration, the design offers versatility for both shallow water exploration and deeper water sailing performance. The boat's moderate displacement of 1,964 pounds combined with 220 square feet of sail area creates a responsive sailing character well-suited to day sailing and weekend coastal cruising. The fractional rig provides excellent sail shape control and reduces weather helm, making it manageable for smaller crews. At just over 21 feet overall, the design maximizes its waterline length of 17.49 feet, contributing to a respectable hull speed of 5.6 knots. The comfort ratio of 10.38 indicates this is definitely a performance-oriented design rather than a heavy cruiser, while the capsize screening formula of 2.53 suggests reasonable stability for coastal waters. The keel-centerboard arrangement allows access to shallow anchorages while maintaining good windward ability when the board is deployed. This Adams 21 would appeal to sailors seeking an affordable entry into keelboat sailing or those wanting a spirited day sailor with trailering capability.

Core Dimensions
LOA (Length Overall) 21.16 ft / 6.45 m
LWL (Waterline Length) 17.49 ft / 5.33 m
Beam 7.91 ft / 2.41 m
Max Draft 4.00 ft / 1.22 m
Min Draft 1.51 ft / 0.46 m
Displacement 1,964.00 lb / 891 kg
Ballast Type Lead
Sail Area (Reported) 220.00 ft² / 20.44 m²
Design & Construction
Hull Type Keel/Cbrd.
Rigging Type Fractional Sloop
Construction FG
Designer Adams
Builder Jarkan Yachts (AU)
First Built 1977
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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
22.5
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
163.88
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
10.38
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
2.53
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. 5.60 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. 494.33 pounds/inch
How It Compares

vs. Hunter 212, Us 21, Venture 21

This boat Similar boats
Dimensions
LOA
Adams 21 ★
21.2 ft
Hunter 212
21.0 ft
Us 21
21.3 ft
Venture 21
21.0 ft
LWL
Adams 21 ★
17.5 ft
Hunter 212
18.0 ft
Us 21
18.0 ft
Venture 21
18.5 ft
Beam
Adams 21 ★
7.9 ft
Hunter 212
9.2 ft
Us 21
8.0 ft
Venture 21
6.8 ft
Displacement
Adams 21 ★
1 lbs
Hunter 212
1 lbs
Us 21
1 lbs
Venture 21
1 lbs
Ballast
Adams 21 ★
Hunter 212
140 lbs
Us 21
200 lbs
Venture 21
400 lbs
Sail Area
Adams 21 ★
220 sq ft
Hunter 212
202 sq ft
Us 21
220 sq ft
Venture 21
Performance
PHRF Rating (lower = faster)
Adams 21 ★
Hunter 212
216 s/nm
Us 21
201 s/nm
Venture 21
252 s/nm
SA / Displacement (higher = more powerful)
Adams 21 ★
22.5
Hunter 212
21.9
Us 21
24.8
Venture 21
Ballast / Disp (higher = stiffer)
Adams 21 ★
Hunter 212
7.8 %
Us 21
Venture 21
26.7 %
Comfort Ratio (higher = more comfortable offshore)
Adams 21 ★
10.4
Hunter 212
7.7
Us 21
8.7
Venture 21
Capsize Screening (lower = safer)
Adams 21 ★
2.53
Hunter 212
3.02
Us 21
2.68
Venture 21
Displacement / Length (lower = lighter)
Adams 21 ★
163
Hunter 212
137
Us 21
Venture 21
105
Hull Speed
Adams 21 ★
5.6 kts
Hunter 212
5.7 kts
Us 21
5.7 kts
Venture 21
Speed Number (higher = faster)
Adams 21 ★
Hunter 212
4.3
Us 21
4.8
Venture 21
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