The Kirby 23 is aggressively canvassed for its weight, with a quick, snappy motion best suited to day sailing, designed for cruising comfort rather than 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 18.8′, the Kirby 23 tops out around 5.8 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √18.8′ LWL = 5.8 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
180s/nm
Typical cruiser — designed for comfort and ease, not podium finishes.
SA / Displacement
24.3
Performance-oriented — carries a lot of canvas for its weight.
Comfort Ratio
12.1
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
2.32
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
521lbs
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
12.1
Quick, snappy motion — better for day sails and racing than long passages.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
2.32
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters
PHRF Fleet Position
Where the Kirby 23 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
Kirby 23
180s/nm
Typical cruiser — designed for comfort and ease, not podium finishes.
Merit 23
201s/nm
Sonic 23
227s/nm
San Juan 23
236s/nm
Pearson 23
240s/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° |
2.7 |
3.5 |
3.9 |
4.0 |
| Close Reach60° |
3.3 |
4.2 |
4.7 |
4.9 |
| Beam Reach90° |
4.1 |
5.1 |
5.7 |
5.8 |
| Broad Reach120–135° |
3.8 |
4.7 |
5.3 |
5.5 |
| Run150–180° |
3.0 |
3.8 |
4.2 |
4.4 |
These are simplified estimates based on hull speed (5.8 kts),
SA/D (24.3), 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 Kirby 23 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–5 kts
5–16 kts
16–24 kts
24+ kts
Ghosting
0–5 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
5–16 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
16–24 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
24+ 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 Kirby 23.
|
Kirby 23 |
Merit 23 |
Pearson 23 |
San Juan 23 |
Sonar |
Sonic 23 |
| Dimensions |
| LOA |
23.0 |
23.0 |
23.0 |
23.0 |
23.0 |
23.0 |
| LWL |
18.8 |
19.0 |
20.0 |
20.3 |
19.9 |
20.0 |
| Beam |
7.8 |
8.0 |
8.0 |
8.0 |
7.8 |
7.6 |
| Displacement |
2 |
1 |
3 |
2 |
2 |
3 |
| Ballast |
900 |
— |
1 |
960 |
930 |
1 |
| Sail Area |
271 |
— |
238 |
— |
265 |
242 |
| Performance |
| PHRF |
180 |
201 |
240 |
236 |
— |
227 |
| SA/Disp |
24.3 |
— |
16.6 |
— |
25.9 |
17.2 |
| Bal/Disp |
— |
— |
37.1 |
35.6 |
44.3 |
44.1 |
| Comfort |
12.1 |
— |
16.3 |
— |
10.0 |
16.9 |
| Capsize |
2.32 |
— |
2.11 |
— |
2.45 |
2.02 |
| Hull Speed |
5.8 |
— |
6.0 |
— |
6.0 |
6.0 |