The Rival 31 is with a steady, comfortable ride offshore.
Hull Speed
The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.
6.6 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 24.5′, the Rival 31 tops out around 6.6 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √24.5′ LWL = 6.6 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
Ballast / Displacement
40.0%
Stiff enough to carry a big genoa comfortably into moderate breeze.
Displacement / Length
340
Moderate-heavy — carries provisions well, deliberate in light air.
Comfort Ratio
31.9
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.73
Below the 2.0 offshore threshold — acceptable for ocean passages.
Hull Speed
6.6kts
Pounds/Inch Immersion
847lbs
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
31.9
Good offshore comfort — steady enough for multi-day passages.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
1.73
Below the 2.0 offshore threshold — acceptable for ocean passages.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters
How It Compares
Side-by-side with the boats most often cross-shopped against the Rival 31.
| Rival 31 | Berwick 31 Westerly | Longbow 31 Westerly | Offshore 31 Cheoy Lee | Seafarer 31 Mkii | Thompson 31 | |
|---|---|---|---|---|---|---|
| Dimensions | ||||||
| LOA | 31.0 | 31.0 | 31.0 | 31.0 | 31.0 | 31.0 |
| LWL | 24.5 | 25.0 | 25.0 | 23.3 | 25.1 | 22.0 |
| Beam | 9.7 | 9.5 | 9.5 | 8.8 | 9.8 | 9.3 |
| Displacement | 11 | 9 | 9 | 10 | 10 | 8 |
| Ballast | 4 | 4 | 4 | 3 | 4 | 3 |
| Sail Area | — | — | 371 | 403 | — | — |
| Performance | ||||||
| SA/Disp | — | — | 13.4 | 13.3 | — | — |
| Bal/Disp | 40.0 | 45.3 | — | 35.5 | 47.1 | — |
| Comfort | 31.9 | — | 27.0 | 35.9 | — | 27.5 |
| Capsize | 1.73 | — | 1.80 | 1.59 | — | 1.82 |
| Hull Speed | 6.6 | — | 6.7 | 6.5 | — | 6.3 |