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Tom Thumb 24

Designer: Grahame Shannon  ·  Builder: Various. Plans Available. See Links Below.  ·  First built: 1983
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About the Tom Thumb 24

Designed by Grahame Shannon in 1983, this compact cruiser stands out in the 24-foot category with its traditional gaffhead sloop rig and robust steel or aluminum construction. The Tom Thumb 24 embodies classic sailing aesthetics while delivering practical performance for coastal cruising and extended passages. The boat's long keel configuration provides excellent directional stability and predictable handling characteristics, making it particularly appealing to traditionalists and those seeking a forgiving sailing experience. With a substantial displacement of 7,900 pounds and generous ballast ratio, this design prioritizes seaworthiness over outright speed, reflected in its impressive comfort ratio of 26.99 that indicates exceptional motion comfort in choppy conditions. The gaff rig offers several advantages including easier sail handling, lower center of effort, and the ability to carry effective square sails for downwind passages. Combined with the steel or aluminum construction, these features make the Tom Thumb 24 well-suited for serious coastal cruising and short-handed sailing. Available as plans from various sources, this design appeals to amateur builders seeking a proven offshore-capable vessel. The capsize screening formula of 1.91 suggests good stability characteristics, while the moderate sail area provides manageable power for extended cruising adventures.

Core Dimensions
LOA (Length Overall) 23.83 ft / 7.26 m
LWL (Waterline Length) 22.00 ft / 6.71 m
Beam 9.50 ft / 2.90 m
Max Draft 4.00 ft / 1.22 m
Displacement 7,900.00 lb / 3,583 kg
Ballast 3,000.00 lb / 1,361 kg
Sail Area (Reported) 350.00 ft² / 32.52 m²
Design & Construction
Hull Type Long Keel
Rigging Type Gaffhead Sloop
Construction Steel/ALU
Designer Grahame Shannon
Builder Various. Plans available. See links below.
First Built 1983
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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
14.16
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
37.97
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
331.22
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
26.99
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
1.91
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. 6.29 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. 746.78 pounds/inch
How It Compares

vs. Achilles 24, Com Pac 23 Mk Iv, Ranger 24, Shaw 24 Yawl, Westwind 24 Paceship

This boat Similar boats
Dimensions
LOA
Tom Thumb 24 ★
23.8 ft
Achilles 24
23.8 ft
Com Pac 23 Mk Iv
23.9 ft
Ranger 24
23.9 ft
Shaw 24 Yawl
23.9 ft
Westwind 24 Paceship
23.9 ft
LWL
Tom Thumb 24 ★
22.0 ft
Achilles 24
19.5 ft
Com Pac 23 Mk Iv
20.2 ft
Ranger 24
20.0 ft
Shaw 24 Yawl
18.5 ft
Westwind 24 Paceship
18.1 ft
Beam
Tom Thumb 24 ★
9.5 ft
Achilles 24
7.1 ft
Com Pac 23 Mk Iv
7.8 ft
Ranger 24
8.3 ft
Shaw 24 Yawl
7.4 ft
Westwind 24 Paceship
8.0 ft
Displacement
Tom Thumb 24 ★
7 lbs
Achilles 24
2 lbs
Com Pac 23 Mk Iv
3 lbs
Ranger 24
3 lbs
Shaw 24 Yawl
4 lbs
Westwind 24 Paceship
4 lbs
Ballast
Tom Thumb 24 ★
3 lbs
Achilles 24
1 lbs
Com Pac 23 Mk Iv
1 lbs
Ranger 24
1 lbs
Shaw 24 Yawl
1 lbs
Westwind 24 Paceship
2 lbs
Sail Area
Tom Thumb 24 ★
350 sq ft
Achilles 24
210 sq ft
Com Pac 23 Mk Iv
Ranger 24
Shaw 24 Yawl
270 sq ft
Westwind 24 Paceship
Performance
SA / Displacement (higher = more powerful)
Tom Thumb 24 ★
14.2
Achilles 24
17.8
Com Pac 23 Mk Iv
Ranger 24
Shaw 24 Yawl
15.2
Westwind 24 Paceship
Ballast / Disp (higher = stiffer)
Tom Thumb 24 ★
38.0 %
Achilles 24
50.5 %
Com Pac 23 Mk Iv
44.7 %
Ranger 24
44.4 %
Shaw 24 Yawl
Westwind 24 Paceship
51.2 %
Comfort Ratio (higher = more comfortable offshore)
Tom Thumb 24 ★
27.0
Achilles 24
14.2
Com Pac 23 Mk Iv
Ranger 24
Shaw 24 Yawl
25.5
Westwind 24 Paceship
Capsize Screening (lower = safer)
Tom Thumb 24 ★
1.91
Achilles 24
2.06
Com Pac 23 Mk Iv
Ranger 24
Shaw 24 Yawl
1.76
Westwind 24 Paceship
Displacement / Length (lower = lighter)
Tom Thumb 24 ★
331
Achilles 24
156
Com Pac 23 Mk Iv
163
Ranger 24
175
Shaw 24 Yawl
Westwind 24 Paceship
349
Hull Speed
Tom Thumb 24 ★
6.3 kts
Achilles 24
5.9 kts
Com Pac 23 Mk Iv
Ranger 24
Shaw 24 Yawl
5.8 kts
Westwind 24 Paceship
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