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Islander 40 Ms
Designer: Charles Davies  ·  Builder: Islander (Usa)  ·  First built: 1970
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About the Islander 40 Ms

Designed by Charles Davies and built by Islander USA starting in 1970, this masthead ketch represents classic American cruising yacht design from the golden age of fiberglass boatbuilding. With her traditional long keel configuration and substantial 28,000-pound displacement, the Islander 40 Ms prioritizes seaworthiness and comfort over pure performance. The yacht's generous beam of 13.17 feet creates spacious accommodations below, while her moderate draft of 4.75 feet opens up more cruising destinations than deeper-drafted vessels. Her masthead ketch rig with 720 square feet of sail area provides versatile sail handling options, particularly appreciated during long passages or when sailing short-handed. Built for serious coastal and offshore cruising, this yacht excels in comfort with a notable comfort ratio of 38.86, indicating excellent motion characteristics in rough seas. The capsize screening formula of 1.74 demonstrates good stability for extended offshore passages. While not built for speed, her hull speed potential of 7.64 knots is respectable for a traditional cruising design. The Islander 40 Ms appeals to sailors seeking a proven, comfortable platform for extended cruising, offering the security and sea-kindly motion that comes with her substantial construction and time-tested design philosophy.

Core Dimensions
LOA (Length Overall) 44.00 ft / 13.41 m
LWL (Waterline Length) 32.50 ft / 9.91 m
Beam 13.17 ft / 4.01 m
Max Draft 4.75 ft / 1.45 m
Displacement 28,000.00 lb / 12,701 kg
Ballast 6,000.00 lb / 2,722 kg
Sail Area (Reported) 720.00 ft² / 66.89 m²
Design & Construction
Hull Type Long Keel
Rigging Type Masthead Ketch
Construction FG
Designer Charles Davies
Builder Islander (USA)
First Built 1970
Related Sailboats ["Csy 44 Mid Cockpit" · "Endurance 44" · "Bounty 44" · "Antigua 44" · "Cherubini 44"]
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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
 12.54
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
 21.43
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
 364.13
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
 38.86
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
 1.74
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. 7.64 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
 0.97
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. 1,529.38 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. 11.71
Rig Dimensions
I (Foretriangle Height) 45.00 ft / 13.72 m
J (Foretriangle Base) 17.30 ft / 5.27 m
P (Mainsail Luff) 39.00 ft / 11.89 m
E (Mainsail Foot) 14.50 ft / 4.42 m
SA Fore 389.25 ft² / 36.16 m²
SA Main 282.75 ft² / 26.27 m²
SA Total (100%) 672.00 ft² / 62.43 m²
Est. Forestay Length 48.21 ft / 14.69 m
How It Compares

vs. Antigua 44, Bounty 44, Endurance 44

This boat Similar boats
Dimensions
LOA
Islander 40 Ms ★
44.0 ft
Antigua 44
44.0 ft
Bounty 44
44.0 ft
Endurance 44
44.0 ft
LWL
Islander 40 Ms ★
32.5 ft
Antigua 44
36.3 ft
Bounty 44
32.3 ft
Endurance 44
37.0 ft
Beam
Islander 40 Ms ★
13.2 ft
Antigua 44
13.3 ft
Bounty 44
13.3 ft
Endurance 44
13.0 ft
Displacement
Islander 40 Ms ★
28 lbs
Antigua 44
38 lbs
Bounty 44
31 lbs
Endurance 44
38 lbs
Ballast
Islander 40 Ms ★
6 lbs
Antigua 44
14 lbs
Bounty 44
8 lbs
Endurance 44
16 lbs
Performance
Ballast / Disp (higher = stiffer)
Islander 40 Ms ★
21.4 %
Antigua 44
36.8 %
Bounty 44
26.5 %
Endurance 44
42.1 %
Displacement / Length (lower = lighter)
Islander 40 Ms ★
364
Antigua 44
353
Bounty 44
412
Endurance 44
334
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