Irwin 37
Core Dimensions
LOA (Length Overall)
37.00 ft / 11.28 m
LWL (Waterline Length)
30.00 ft / 9.14 m
Beam
11.50 ft / 3.51 m
Max Draft
5.50 ft / 1.68 m
Displacement
18,000.00 lb / 8,165 kg
Ballast
6,700.00 lb / 3,039 kg
Sail Area (Reported)
558.00 ft² / 51.84 m²
Design & Construction
Hull Type
Fin with rudder on skeg
Rigging Type
Masthead Sloop
Construction
FG
Designer
Ted Irwin
Builder
Irwin Yachts
First Built
1971
Last Built
1975
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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
138
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
13.05
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
33.51
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
1.76
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.
7.34
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
1.43
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.
1.0
Rig Dimensions
I (Foretriangle Height)
42.0
J (Foretriangle Base)
14.33
P (Mainsail Luff)
35.5
E (Mainsail Foot)
14.5
SA Fore
300.93
SA Main
257.38
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