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Seguin 40
Designer: Craig V. Walters  ·  Builder: Lyman Morse Boatbuilding (Usa)  ·  First built: 1983
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About the Seguin 40

Designed by Craig V. Walters and built by the renowned Lyman Morse Boatbuilding, this rare 40-footer represents classic Maine craftsmanship from the early 1980s. With only five hulls constructed beginning in 1983, the Seguin 40 stands as an exclusive example of quality fiberglass construction combined with thoughtful design principles. The boat's substantial displacement of 17,200 pounds and impressive 50% ballast ratio create exceptional stability and seaworthiness, making it well-suited for serious coastal cruising and offshore passages. The deep 7.33-foot draft and keel/centerboard configuration provide excellent upwind performance while offering shallow-water versatility when the board is raised. With a moderate sail area-to-displacement ratio of 18.15 and comfortable 28.25 comfort ratio, this masthead sloop prioritizes seakindly motion and steady progress over pure speed. The low capsize screening value of 1.89 indicates strong stability characteristics that inspire confidence in challenging conditions. Lyman Morse's reputation for meticulous construction quality ensures these boats have aged gracefully. The Seguin 40 appeals to discerning sailors seeking a capable, well-built cruiser that balances performance with comfort, though its rarity means finding one requires patience and typically commands premium pricing.

Core Dimensions
LOA (Length Overall) 39.67 ft / 12.09 m
LWL (Waterline Length) 31.25 ft / 9.53 m
Beam 12.16 ft / 3.71 m
Max Draft 7.33 ft / 2.23 m
Min Draft 2.33 ft / 0.71 m
Displacement 17,200.00 lb / 7,802 kg
Ballast 8,600.00 lb / 3,901 kg
Ballast Type Lead
Sail Area (Reported) 753.00 ft² / 69.96 m²
Design & Construction
Hull Type Keel/Cbrd.
Rigging Type Masthead Sloop
Construction FG
Designer Craig V. Walters
Builder Lyman Morse Boatbuilding (USA)
First Built 1983
Number Built 5
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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
 99
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
 18.15
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
 50
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
 251.61
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
 28.25
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
 1.89
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. 7.49 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
 2.26
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. 1,357.78 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. 18.15
Rig Dimensions
I (Foretriangle Height) 52.00 ft / 15.85 m
J (Foretriangle Base) 15.70 ft / 4.79 m
P (Mainsail Luff) 46.00 ft / 14.02 m
E (Mainsail Foot) 15.00 ft / 4.57 m
SA Fore 408.20 ft² / 37.92 m²
SA Main 345.00 ft² / 32.05 m²
SA Total (100%) 753.20 ft² / 69.97 m²
Est. Forestay Length 54.32 ft / 16.56 m
Engine & Accommodations
Engine Type Diesel
Horsepower 22
Fuel Capacity 40 gals / 151 L
Water Capacity 120 gals / 454 L
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