Hull Speed
The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.
7.0 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 27.5′, the Thistle 31 tops out around 7.0 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √27.5′ LWL = 7.0 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
429
Heavy displacement — a slow, steady, seakindly hull.
Hull Speed
7.0kts
Pounds/Inch Immersion
6lbs
Weight needed to sink the hull one inch — loading sensitivity.
PHRF Fleet Position
Where the Thistle 31 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Island Packet 31
Rasmus 31
Cape George 31
Bombay Clipper 31
How It Compares
Side-by-side with the boats most often cross-shopped against the Thistle 31.
| Thistle 31 | Bombay Clipper 31 | Cape George 31 | Island Packet 31 | Offshore 31 Cheoy Lee | Rasmus 31 | |
|---|---|---|---|---|---|---|
| Dimensions | ||||||
| LOA | 31.1 | 31.0 | 31.0 | 31.0 | 31.0 | 31.0 |
| LWL | 27.5 | 25.6 | 27.5 | 27.8 | 23.3 | 24.8 |
| Beam | 11.0 | 11.0 | 9.6 | 11.6 | 8.8 | 10.0 |
| Displacement | 20 | 10 | 15 | 11 | 10 | 9 |
| Ballast | — | 3 | 7 | 4 | 3 | — |
| Sail Area | — | 419 | 634 | 530 | 403 | 414 |
| Performance | ||||||
| PHRF | — | 234 | 218 | 186 | — | 201 |
| SA/Disp | — | 14.5 | 16.2 | 17.2 | 13.3 | 14.8 |
| Bal/Disp | — | 34.0 | 49.3 | 40.9 | 35.5 | — |
| Comfort | — | 23.3 | 42.3 | 22.6 | 35.9 | 25.7 |
| Capsize | — | 2.05 | 1.53 | 2.09 | 1.59 | 1.89 |
| Hull Speed | — | 6.8 | 7.0 | 7.1 | 6.5 | 6.7 |