Seidelmann 245 vs Sonar
How do the Seidelmann 245 and Sonar compare? Below, their dimensions, displacement, sail area and the standard design ratios side by side, followed by a data-driven summary.
Seidelmann 245 
Sonar | Seidelmann 245 | Sonar | |
|---|---|---|
| Length overall | 24.2 ft7.37 m | 23.0 ft7.00 m |
| Waterline length | 20.5 ft6.25 m | 19.9 ft6.07 m |
| Beam | 8.0 ft2.44 m | 7.9 ft2.40 m |
| Draft | 4.4 ft1.35 m | 3.9 ft1.19 m |
| Displacement | 3,000 lb1,361 kg | 2,100 lb953 kg |
| Ballast | 1,300 lb590 kg | 930 lb422 kg |
| Sail area | 267 ft²24.8 m² | 265 ft²24.6 m² |
| SA / Displacement | 20.54 | 25.86 |
| Displacement / Length | 155 | 119 |
| Comfort ratio | 13.4 | 10.0 |
| Capsize screening | 2.22 | 2.46 |
| Hull speed (kn) | 6.1 | 6.0 |
Seidelmann 245 vs Sonar: the short version
- The Seidelmann 245 is the larger boat at 24.2 ft7.37 m LOA versus 23.0 ft7.00 m for the Sonar.
- The Seidelmann 245 is heavier, displacing about 43% more, which usually means a steadier but slower-to-accelerate hull.
- On sail area/displacement the Sonar carries the more powerful rig (25.9 vs 20.5), favouring lighter-air performance.
- The Seidelmann 245 scores higher on the Brewer comfort ratio, suggesting an easier motion in a seaway.
- By the capsize screening formula the Seidelmann 245 rates better for offshore work (2.22 vs 2.46).
Ratios are guidelines computed from published specs; condition, layout and gear matter as much as the numbers.