Hull Speed
The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.
4.9 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 13.5′, the Us1 tops out around 4.9 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √13.5′ LWL = 4.9 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
Displacement / Length
34
Ultralight — responsive and fast, but carries less stores.
Hull Speed
4.9kts
Pounds/Inch Immersion
1lbs
Weight needed to sink the hull one inch — loading sensitivity.
How It Compares
Side-by-side with the boats most often cross-shopped against the Us1.
| Us1 | 470 | Bandit 15 | Coronado 15 | Snipe | Windmill | |
|---|---|---|---|---|---|---|
| Dimensions | ||||||
| LOA | 15.4 | 15.4 | 15.3 | 15.3 | 15.5 | 15.5 |
| LWL | 13.5 | 14.6 | 15.0 | — | 12.7 | 14.5 |
| Beam | 4.6 | 5.5 | 5.9 | 5.7 | 5.0 | 4.8 |
| Displacement | 190 | 269 | 260 | 385 | 380 | 198 |
| Sail Area | — | 137 | — | 139 | 128 | 119 |
| Performance | ||||||
| SA/Disp | — | 52.7 | — | 42.1 | 39.1 | 56.1 |
| Comfort | — | 2.9 | — | 4.3 | 5.1 | 2.6 |
| Capsize | — | 3.41 | — | — | 2.76 | 3.26 |
| Hull Speed | — | 5.1 | — | 4.8 | 4.8 | 5.1 |