What is the Irwin 37's sail area to displacement ratio?

The Irwin 37 has a Sail Area to Displacement ratio (SA/D) of 13.05. Values between 14–18 are typical cruising sailboats; 18–22 is cruiser/racer; over 22 is performance racing.

What is the Irwin 37's comfort ratio?

The Irwin 37 has a Ted Brewer Comfort Ratio of 33.51. A ratio over 30 indicates good offshore comfort; over 40 is very comfortable offshore.

Is the Irwin 37 safe for offshore sailing?

The Irwin 37 has a Capsize Screening Formula value of 1.76. Values under 2.0 are considered acceptable for offshore sailing; under 1.8 is ideal.

What is the hull speed of the Irwin 37?

The theoretical hull speed of the Irwin 37 is 7.34 knots, calculated from its waterline length.

How much does a Irwin 37 weigh?

The Irwin 37 has a displacement of 18,000.00 lb and a length overall (LOA) of 37.00 ft.

How much does a used Irwin 37 cost?

Based on 1 recent market listings, used Irwin 37 sailboats typically sell for between $48,000 and $48,000, with a median asking price of $48,000. Price varies significantly based on year, condition, location, and included equipment.

Who designed the Irwin 37?

The Irwin 37 was designed by Ted Irwin, first built in 1971.

Irwin 37 Performance — PHRF, SA/D, Hull Speed & Sailing Characteristics

The Irwin 37 is modestly canvassed and unhurried, with a steady, comfortable ride offshore, and respectable in club racing.

Hull Speed

The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.

7.3 kts

A displacement hull pushes a bow wave whose speed is limited by the waterline length. With a waterline of 30.0′, the Irwin 37 tops out around 7.3 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.

1.34 × √30.0′ LWL = 7.3 kts

Performance Ratios

Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.

PHRF Rating

138s/nm

Cruiser/racer — competitive in club racing, comfortable cruising.

SA / Displacement

13.1

Modestly canvassed — a comfortable, unhurried cruiser.

Ballast / Displacement

37.2%

Typical cruising ballast — balanced stability and motion underway.

Displacement / Length

298

Moderate-heavy — carries provisions well, deliberate in light air.

Comfort Ratio

33.5

Good offshore comfort — steady enough for multi-day passages.

Capsize Screening

1.76

Below the 2.0 offshore threshold — acceptable for ocean passages.

Hull Speed

7.3kts

S# (Speed Number)

1.4

Pounds/Inch Immersion

1lbs

Weight needed to sink the hull one inch — loading sensitivity.

Motion & Offshore Suitability

Two ratios that matter most when you're planning passages — how the boat feels in a seaway, and whether the hull geometry is suitable for open ocean.

Comfort Ratio

33.5

Good offshore comfort — steady enough for multi-day passages.

Under 20 — Snappy, racing motion

20–30 — Acceptable coastal

30–40 — Good offshore comfort

Over 40 — Very comfortable offshore

Capsize Screening Formula

1.76

Below the 2.0 offshore threshold — acceptable for ocean passages.

Under 2.0 — Acceptable for offshore

Over 2.0 — Coastal / protected waters

PHRF Fleet Position

Where the Irwin 37 sits on the PHRF handicap spectrum — lower numbers mean faster boats.

Racer 0–90

Cruiser/Racer 90–150

Cruiser 150–210

C&C 37 60s/nm

Irwin 37 138s/nm Cruiser/racer — competitive in club racing, comfortable cruising.

Gulfstar 37 153s/nm

Endeavour 37 174s/nm

Tartan 37 174s/nm

Estimated Speed by Wind

Rough boat speed estimates at different true wind speeds and points of sail — derived from hull speed, SA/D, and displacement, not measured polars.

Point of Sail	6 kts TWS	10 kts TWS	15 kts TWS	20 kts TWS
Close-hauled40–50°	2.6	3.3	3.7	3.8
Close Reach60°	3.1	4.0	4.4	4.6
Beam Reach90°	3.8	4.9	5.4	5.7
Broad Reach120–135°	3.6	4.5	5.0	5.2
Run150–180°	2.8	3.6	4.0	4.2

These are simplified estimates based on hull speed (7.3 kts), SA/D (13.1), and empirical efficiency curves — not instrument-measured polars. Real-world speed varies with sea state, bottom condition, sail trim, and current. Speeds in gold approach hull speed; bold gold means near or at hull speed.

Wind Range & Comfort Envelope

Estimated wind ranges for comfortable sailing on the Irwin 37 — based on sail area, ballast, and displacement characteristics.

Ghost

Sweet Spot

Reef

Heavy

0–8 kts 8–22 kts 22–30 kts 30+ kts

Ghosting

0–8 kts

Light air, motor-sailing likely. Need patience and a light genoa.

Sweet Spot

8–22 kts

Comfortable under full sail. Best speed-to-comfort ratio.

Time to Reef

22–30 kts

Time to shorten sail. Reef the main, swap to a working jib.

Heavy Weather

30+ kts

Storm conditions. Storm jib or bare poles. Seek shelter if coastal.

How It Compares

Side-by-side with the boats most often cross-shopped against the Irwin 37.

	Irwin 37	C&C 37	Endeavour 37	Gulfstar 37	Tartan 37	Valiant 37
Dimensions
LOA	37.0	—	37.0	37.0	37.0	37.0
LWL	30.0	—	30.0	32.0	25.5	31.6
Beam	11.5	—	11.6	11.8	10.5	11.5
Displacement	18	—	20	19	14	17
Ballast	6	—	8	8	4	6
Sail Area	558	—	574	614	654	667
Performance
PHRF	138	60	174	153	174	—
SA/Disp	13.1	—	12.5	13.6	17.6	16.2
Bal/Disp	37.2	—	40.0	41.0	—	39.4
Comfort	33.5	—	36.9	33.5	34.0	30.6
Capsize	1.76	—	1.71	1.76	1.72	1.79
Hull Speed	7.3	—	7.3	7.6	6.8	7.5