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Seidelmann 25
Designer: Bob Seidelmann  ·  Builder: Seidelmann Yachts (Usa)  ·  First built: 1977
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About the Seidelmann 25

Introduced in 1977, this compact cruiser from designer Bob Seidelmann represents thoughtful engineering in a trailerable package. Built by Seidelmann Yachts with fiberglass construction, the boat features a modern fin keel with spade rudder configuration that delivers responsive handling and good upwind performance despite its modest 24.60-foot overall length. The design strikes an appealing balance between comfort and sailing ability, with a generous 9.50-foot beam providing stable accommodations while maintaining a respectable sail area of 281 square feet on a masthead sloop rig. The substantial displacement of 4,600 pounds, nearly half of which is ballast, contributes to predictable sailing characteristics and seaworthiness that exceeds what many expect from a boat this size. With a comfort ratio of 16.58, the Seidelmann 25 leans toward the performance end of the spectrum while still offering adequate creature comforts for weekend cruising or coastal exploration. The 4.33-foot draft allows access to moderately shallow waters, making it versatile for gunkholing and small harbor exploration. This design appeals to sailors seeking their first keelboat or those wanting a manageable coastal cruiser that can be trailered to different sailing grounds.

Core Dimensions
LOA (Length Overall) 24.60 ft / 7.50 m
LWL (Waterline Length) 20.00 ft / 6.10 m
Beam 9.50 ft / 2.90 m
Max Draft 4.33 ft / 1.32 m
Displacement 4,600.00 lb / 2,087 kg
Ballast 2,200.00 lb / 998 kg
Sail Area (Reported) 281.00 ft² / 26.11 m²
Design & Construction
Hull Type Fin w/spade rudder
Rigging Type Masthead Sloop
Construction FG
Designer Bob Seidelmann
Builder Seidelmann Yachts (USA)
First Built 1977
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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
 217
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
 16.3
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
 47.83
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
 256.7
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
 16.58
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
 2.29
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. 5.99 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
 2.05
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. 678.89 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. 16.35
Rig Dimensions
I (Foretriangle Height) 31.00 ft / 9.45 m
J (Foretriangle Base) 10.92 ft / 3.33 m
P (Mainsail Luff) 25.00 ft / 7.62 m
E (Mainsail Foot) 9.00 ft / 2.74 m
SA Fore 169.26 ft² / 15.72 m²
SA Main 112.50 ft² / 10.45 m²
SA Total (100%) 281.76 ft² / 26.18 m²
Est. Forestay Length 32.87 ft / 10.02 m
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