The Irwin 40 is well-powered with enough sail area to move in light air, with acceptable motion comfort for coastal passages, and respectable in club racing.
Hull Speed
The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 31.2′, the Irwin 40 tops out around 7.5 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √31.2′ LWL = 7.5 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
147s/nm
Cruiser/racer — competitive in club racing, comfortable cruising.
SA / Displacement
18.0
Powerful cruiser/racer — quick in light air, reef early when it pipes up.
Comfort Ratio
27.5
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
1.90
Below the 2.0 offshore threshold — acceptable for ocean passages.
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
27.5
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
1.90
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 40 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
Newport 41
113s/nm
Irwin 40 Citation
122s/nm
Irwin 40
147s/nm
Cruiser/racer — competitive in club racing, comfortable cruising.
Formosa 41
221s/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° |
3.1 |
3.9 |
4.3 |
4.5 |
| Close Reach60° |
3.7 |
4.7 |
5.2 |
5.5 |
| Beam Reach90° |
4.5 |
5.7 |
6.4 |
6.7 |
| Broad Reach120–135° |
4.2 |
5.3 |
5.9 |
6.2 |
| Run150–180° |
3.4 |
4.2 |
4.7 |
4.9 |
These are simplified estimates based on hull speed (7.5 kts),
SA/D (18.0), 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 40 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–6 kts
6–18 kts
18–26 kts
26+ kts
Ghosting
0–6 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
6–18 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
18–26 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
26+ 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 40.
|
Irwin 40 |
Formosa 41 |
Irwin 40 Citation |
Irwin 40 Mkii |
Newport 41 |
Offshore 41 Cheoy Lee |
| Dimensions |
| LOA |
40.8 |
40.9 |
40.8 |
40.8 |
40.7 |
40.9 |
| LWL |
31.2 |
32.0 |
31.2 |
31.2 |
30.0 |
32.5 |
| Beam |
12.2 |
12.2 |
12.2 |
12.2 |
11.2 |
12.8 |
| Displacement |
16 |
28 |
16 |
16 |
17 |
21 |
| Ballast |
— |
9 |
— |
6 |
8 |
8 |
| Sail Area |
738 |
780 |
738 |
737 |
— |
833 |
| Performance |
| PHRF |
147 |
221 |
122 |
— |
113 |
— |
| SA/Disp |
18.0 |
13.6 |
18.0 |
18.0 |
— |
17.5 |
| Bal/Disp |
— |
32.9 |
— |
38.5 |
46.8 |
42.1 |
| Comfort |
27.5 |
44.8 |
27.5 |
27.5 |
— |
31.4 |
| Capsize |
1.90 |
1.61 |
1.90 |
1.90 |
— |
1.85 |
| Hull Speed |
7.5 |
7.6 |
7.5 |
7.5 |
— |
7.6 |