The Irwin 37 2 is modestly canvassed and unhurried, with a steady, comfortable ride offshore.
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 2 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.
SA / Displacement
12.8
Modestly canvassed — a comfortable, unhurried cruiser.
Comfort Ratio
37.2
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.70
Below the 2.0 offshore threshold — acceptable for ocean passages.
Hull Speed
7.3kts
S# (Speed Number)
1.2
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
37.2
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
1.70
Below the 2.0 offshore threshold — acceptable for ocean passages.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters
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 | 3.6 | 3.8 |
| Close Reach60° | 3.1 | 3.9 | 4.4 | 4.6 |
| Beam Reach90° | 3.8 | 4.8 | 5.4 | 5.6 |
| Broad Reach120–135° | 3.5 | 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 (12.8), 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 2 — based on sail area, ballast, and displacement characteristics.
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.