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Amphibi Con
Designer: Cyrus Hamlin, Farham Butler  ·  Builder: Mount Desert Yachts/Sailstar Boats (Usa)  ·  First built: 1954
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About the Amphibi Con

Originally designed by Cyrus Hamlin and Farham Butler in 1954, this 25-foot fractional sloop represents a classic era of American sailboat design when wood strip construction with fiberglass overlay was becoming the preferred method for quality small craft. With 125 hulls built by Mount Desert Yachts and later Sailstar Boats, the Amphibi Con developed a modest but dedicated following among sailors seeking a capable coastal cruiser. The boat's hybrid keel/centerboard configuration offers versatility that appeals to sailors who want both shoal water accessibility and offshore stability. Her substantial displacement of 3,500 pounds and generous ballast-to-displacement ratio provide reassuring stability, while the moderate sail area delivers predictable performance without being overpowering for smaller crews. Notable design characteristics include a comfortable beam that maximizes interior space without sacrificing sailing performance, and a hull speed capability that makes her suitable for extended coastal passages. The comfort ratio of 15.51 suggests this boat favors cruising over racing, while her capsize screening indicates reasonable stability for protected offshore work. Best suited for coastal cruising, weekend getaways, and protected bay sailing, the Amphibi Con appeals to sailors who appreciate traditional construction methods and timeless design aesthetics in a manageable package.

Core Dimensions
LOA (Length Overall) 25.42 ft / 7.75 m
LWL (Waterline Length) 21.67 ft / 6.61 m
Beam 7.75 ft / 2.36 m
Max Draft 4.25 ft / 1.30 m
Min Draft 2.33 ft / 0.71 m
Displacement 3,500.00 lb / 1,588 kg
Ballast 1,100.00 lb / 499 kg
Sail Area (Reported) 277.00 ft² / 25.73 m²
Design & Construction
Hull Type Keel/Cbrd.
Rigging Type Fractional Sloop
Construction wood strip/FG
Designer Cyrus Hamlin, Farham Butler
Builder Mount Desert Yachts/Sailstar Boats (USA)
First Built 1954
Number Built 125
Associations Amphibi-Con (Mount Desert Yachts, Controversy)
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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
19.28
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
31.43
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
153.55
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
15.51
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
2.04
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. 6.24 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
3.63
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. 600.08 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. 19.26
Rig Dimensions
I (Foretriangle Height) 24.00 ft / 7.32 m
J (Foretriangle Base) 9.50 ft / 2.90 m
P (Mainsail Luff) 26.75 ft / 8.15 m
E (Mainsail Foot) 12.17 ft / 3.71 m
SA Fore 114.00 ft² / 10.59 m²
SA Main 162.77 ft² / 15.12 m²
SA Total (100%) 276.77 ft² / 25.71 m²
Est. Forestay Length 25.81 ft / 7.87 m
How It Compares

vs. Ariel 26 Pearson, Offshore 26 Cheoy Lee, Victoire 26

This boat Similar boats
Dimensions
LOA
Amphibi Con ★
25.4 ft
Ariel 26 Pearson
25.6 ft
Offshore 26 Cheoy Lee
25.6 ft
Victoire 26
25.4 ft
LWL
Amphibi Con ★
21.7 ft
Ariel 26 Pearson
18.5 ft
Offshore 26 Cheoy Lee
23.3 ft
Victoire 26
20.2 ft
Beam
Amphibi Con ★
7.8 ft
Ariel 26 Pearson
8.0 ft
Offshore 26 Cheoy Lee
8.8 ft
Victoire 26
8.4 ft
Displacement
Amphibi Con ★
3 lbs
Ariel 26 Pearson
5 lbs
Offshore 26 Cheoy Lee
4 lbs
Victoire 26
5 lbs
Ballast
Amphibi Con ★
1 lbs
Ariel 26 Pearson
2 lbs
Offshore 26 Cheoy Lee
Victoire 26
1 lbs
Sail Area
Amphibi Con ★
277 sq ft
Ariel 26 Pearson
Offshore 26 Cheoy Lee
328 sq ft
Victoire 26
Performance
SA / Displacement (higher = more powerful)
Amphibi Con ★
19.3
Ariel 26 Pearson
Offshore 26 Cheoy Lee
19.3
Victoire 26
Ballast / Disp (higher = stiffer)
Amphibi Con ★
31.4 %
Ariel 26 Pearson
44.9 %
Offshore 26 Cheoy Lee
Victoire 26
34.0 %
Comfort Ratio (higher = more comfortable offshore)
Amphibi Con ★
15.5
Ariel 26 Pearson
Offshore 26 Cheoy Lee
16.0
Victoire 26
23.1
Capsize Screening (lower = safer)
Amphibi Con ★
2.04
Ariel 26 Pearson
Offshore 26 Cheoy Lee
2.14
Victoire 26
1.90
Displacement / Length (lower = lighter)
Amphibi Con ★
153
Ariel 26 Pearson
361
Offshore 26 Cheoy Lee
159
Victoire 26
299
Hull Speed
Amphibi Con ★
6.2 kts
Ariel 26 Pearson
Offshore 26 Cheoy Lee
6.5 kts
Victoire 26
6.0 kts
Speed Number (higher = faster)
Amphibi Con ★
3.6
Ariel 26 Pearson
Offshore 26 Cheoy Lee
3.5
Victoire 26
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