Hull Speed
The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.
5.6 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 17.3′, the Seagull 18 tops out around 5.6 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √17.3′ LWL = 5.6 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
20.8%
Light ballast — tends to be tender; reef earlier than the numbers suggest.
Displacement / Length
146
Ultralight — responsive and fast, but carries less stores.
Hull Speed
5.6kts
Pounds/Inch Immersion
3lbs
Weight needed to sink the hull one inch — loading sensitivity.
PHRF Fleet Position
Where the Seagull 18 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Minuet
How It Compares
Side-by-side with the boats most often cross-shopped against the Seagull 18.
| Seagull 18 | Alacrity 19 | Goldeneye Herreshoff | Hurley 18 | Minuet | Peregrine Proctor | |
|---|---|---|---|---|---|---|
| Dimensions | ||||||
| LOA | 18.5 | 18.5 | 18.3 | 18.5 | 18.3 | 18.5 |
| LWL | 17.3 | 17.0 | 15.8 | 14.5 | 12.8 | 17.3 |
| Beam | 6.8 | 6.9 | 6.3 | 6.7 | 5.4 | 5.6 |
| Displacement | 1 | 1 | 2 | 2 | 1 | 720 |
| Ballast | 350 | 480 | 1 | 1 | 420 | 375 |
| Sail Area | — | 158 | 193 | 180 | 127 | — |
| Performance | ||||||
| PHRF | — | — | — | — | 336 | — |
| SA/Disp | — | 19.3 | 16.8 | 16.3 | 20.4 | — |
| Bal/Disp | 20.8 | 32.0 | 52.8 | 42.6 | 42.0 | 52.1 |
| Comfort | — | 10.1 | 20.0 | 18.5 | 11.2 | — |
| Capsize | — | 2.42 | 1.87 | 2.01 | 2.17 | — |
| Hull Speed | — | 5.5 | 5.3 | 5.1 | 4.8 | — |