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Irwin 37 4
Designer: Ted Irwin  ·  Builder: Irwin Yachts  ·  First built: 1977
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About the Irwin 37 4

Built during Irwin Yachts' productive era, this 37-footer represents the company's commitment to creating affordable cruising sailboats for the growing recreational sailing market. Irwin established a solid reputation for producing practical, well-built vessels that offered good value for coastal cruising and extended passages. This model likely features the classic Irwin characteristics that made the brand popular among cruising sailors: a spacious interior layout optimized for comfort, a moderate displacement hull designed for steady sailing performance, and construction quality that balanced durability with affordability. The design philosophy emphasized livability below decks while maintaining respectable sailing capabilities. The boat would be well-suited for coastal cruising, weekend sailing, and potentially longer passages in capable hands. Irwin's designs typically incorporated sensible deck layouts and rigging arrangements that made them manageable for couples or small crews. The hull form likely provides a good compromise between interior volume and sailing performance, making it an attractive option for sailors prioritizing comfort without sacrificing seaworthiness. For prospective buyers seeking a mid-sized cruiser with proven genetics and reasonable maintenance requirements, this Irwin model represents the brand's practical approach to recreational sailing vessel design.

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 20,000.00 lb / 9,072 kg
Ballast 6,700.00 lb / 3,039 kg
Sail Area (Reported) 627.00 ft² / 58.25 m²
Design & Construction
Hull Type Fin with rudder on skeg
Rigging Type Cutter
Construction FG
Designer Ted Irwin
Builder Irwin Yachts
First Built 1977
Last Built 1982
Related Sailboats ["Endeavour 37" · "Gulfstar 37" · "Valiant 37" · "Irwin 37 5" · "Esprit 37"]
Owner Reviews

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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
 13.67
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
 37.23
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
 1.7
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
 1.29
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) 17.5
P (Mainsail Luff) 35.6
E (Mainsail Foot) 14.6
SA Fore 367.5
SA Main 259.88
How It Compares

vs. Gulfstar 37, Irwin 37 5, Valiant 37

This boat Similar boats
Dimensions
LOA
Irwin 37 4 ★
37.0 ft
Gulfstar 37
37.0 ft
Irwin 37 5
37.0 ft
Valiant 37
37.0 ft
LWL
Irwin 37 4 ★
30.0 ft
Gulfstar 37
32.0 ft
Irwin 37 5
30.0 ft
Valiant 37
31.6 ft
Beam
Irwin 37 4 ★
11.5 ft
Gulfstar 37
11.8 ft
Irwin 37 5
11.5 ft
Valiant 37
11.5 ft
Displacement
Irwin 37 4 ★
20 lbs
Gulfstar 37
19 lbs
Irwin 37 5
20 lbs
Valiant 37
17 lbs
Ballast
Irwin 37 4 ★
6 lbs
Gulfstar 37
8 lbs
Irwin 37 5
7 lbs
Valiant 37
6 lbs
Sail Area
Irwin 37 4 ★
627 sq ft
Gulfstar 37
614 sq ft
Irwin 37 5
625 sq ft
Valiant 37
667 sq ft
Performance
SA / Displacement (higher = more powerful)
Irwin 37 4 ★
13.7
Gulfstar 37
13.6
Irwin 37 5
13.6
Valiant 37
16.2
Comfort Ratio (higher = more comfortable offshore)
Irwin 37 4 ★
37.2
Gulfstar 37
33.5
Irwin 37 5
37.2
Valiant 37
30.6
Capsize Screening (lower = safer)
Irwin 37 4 ★
1.70
Gulfstar 37
1.76
Irwin 37 5
1.70
Valiant 37
1.79
Hull Speed
Irwin 37 4 ★
7.3 kts
Gulfstar 37
7.6 kts
Irwin 37 5
7.3 kts
Valiant 37
7.5 kts
Speed Number (higher = faster)
Irwin 37 4 ★
1.3
Gulfstar 37
1.8
Irwin 37 5
1.3
Valiant 37
2.2
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