Kirby 23 vs Sonic 23
How do the Kirby 23 and Sonic 23 compare? Below, their dimensions, displacement, sail area and the standard design ratios side by side, followed by a data-driven summary.
Kirby 23 
Sonic 23 | Kirby 23 | Sonic 23 | |
|---|---|---|
| Length overall | 23.0 ft7.01 m | 23.0 ft7.01 m |
| Waterline length | 18.8 ft5.73 m | 20.0 ft6.10 m |
| Beam | 7.8 ft2.36 m | 7.6 ft2.31 m |
| Draft | 3.9 ft1.19 m | 3.8 ft1.14 m |
| Displacement | 2,400 lb1,089 kg | 3,400 lb1,542 kg |
| Ballast | 900 lb408 kg | 1,500 lb680 kg |
| Sail area | 273 ft²25.4 m² | 242 ft²22.5 m² |
| SA / Displacement | 24.37 | 17.12 |
| Displacement / Length | 161 | 190 |
| Comfort ratio | 12.1 | 16.9 |
| Capsize screening | 2.32 | 2.02 |
| Hull speed (kn) | 5.8 | 6.0 |
Kirby 23 vs Sonic 23: the short version
- The Kirby 23 and Sonic 23 are close in length (23.0 ft7.01 m vs 23.0 ft7.01 m ).
- The Sonic 23 is heavier, displacing about 42% more, which usually means a steadier but slower-to-accelerate hull.
- On sail area/displacement the Kirby 23 carries the more powerful rig (24.4 vs 17.1), favouring lighter-air performance.
- The Sonic 23 scores higher on the Brewer comfort ratio, suggesting an easier motion in a seaway.
- By the capsize screening formula the Sonic 23 rates better for offshore work (2.02 vs 2.32).
Ratios are guidelines computed from published specs; condition, layout and gear matter as much as the numbers.