The Irwin 27 is moderately powered for comfortable coastal cruising, with acceptable motion comfort for coastal passages.
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 20.5′, the Irwin 27 tops out around 6.1 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √20.5′ LWL = 6.1 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
225s/nm
Heavy or slow cruiser — all about the journey, not the elapsed time.
SA / Displacement
16.2
Moderate sail power — a capable coastal cruiser, not overpowered.
Displacement / Length
342
Moderate-heavy — carries provisions well, deliberate in light air.
Comfort Ratio
25.6
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
1.85
Below the 2.0 offshore threshold — acceptable for ocean passages.
SA/Disp (Calculated)
17.0
Computed from measured I/J/P/E rather than reported sail area.
Pounds/Inch Immersion
635lbs
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
25.6
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
1.85
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 27 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
Santana 27
201s/nm
Cs 27
204s/nm
Cape Dory 27
222s/nm
Irwin 27
225s/nm
Heavy or slow cruiser — all about the journey, not the elapsed time.
Tartan 27
234s/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° |
2.4 |
3.0 |
3.3 |
3.5 |
| Close Reach60° |
2.9 |
3.6 |
4.0 |
4.2 |
| Beam Reach90° |
3.5 |
4.4 |
5.0 |
5.2 |
| Broad Reach120–135° |
3.2 |
4.1 |
4.6 |
4.8 |
| Run150–180° |
2.6 |
3.3 |
3.7 |
3.8 |
These are simplified estimates based on hull speed (6.1 kts),
SA/D (16.2), 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 27 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–7 kts
7–20 kts
20–28 kts
28+ kts
Ghosting
0–7 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
7–20 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
20–28 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
28+ 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 27.
|
Irwin 27 |
Cape Dory 27 |
Columbia 83 |
Cs 27 |
Santana 27 |
Tartan 27 |
| Dimensions |
| LOA |
27.1 |
27.1 |
27.1 |
27.0 |
27.0 |
27.0 |
| LWL |
20.5 |
20.0 |
21.3 |
23.9 |
22.5 |
21.4 |
| Beam |
8.7 |
8.5 |
9.3 |
9.3 |
9.0 |
8.6 |
| Displacement |
6 |
7 |
7 |
6 |
5 |
7 |
| Ballast |
— |
3 |
3 |
2 |
2 |
2 |
| Sail Area |
356 |
365 |
344 |
453 |
348 |
— |
| Performance |
| PHRF |
225 |
222 |
— |
204 |
201 |
234 |
| SA/Disp |
16.2 |
15.3 |
14.7 |
21.8 |
19.1 |
— |
| Bal/Disp |
— |
40.0 |
42.5 |
39.3 |
46.0 |
32.4 |
| Comfort |
25.6 |
30.3 |
25.3 |
19.4 |
17.4 |
— |
| Capsize |
1.85 |
1.74 |
1.91 |
2.05 |
2.11 |
— |
| Hull Speed |
6.1 |
6.0 |
6.2 |
6.6 |
6.4 |
— |