The Thompson 27 is with acceptable motion comfort for coastal passages.
Hull Speed
The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.
6.2 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 21.5′, the Thompson 27 tops out around 6.2 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √21.5′ LWL = 6.2 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
45.4%
Race-oriented ballast ratio — very stiff and powerful.
Displacement / Length
274
Moderate-heavy — carries provisions well, deliberate in light air.
Comfort Ratio
25.6
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
1.75
Below the 2.0 offshore threshold — acceptable for ocean passages.
Hull Speed
6.2kts
Pounds/Inch Immersion
615lbs
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
25.6
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
1.75
Below the 2.0 offshore threshold — acceptable for ocean passages.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters
PHRF Fleet Position
Where the Thompson 27 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Niagara 26
Ericson 27
Islander 27
Coronado 27
How It Compares
Side-by-side with the boats most often cross-shopped against the Thompson 27.
| Thompson 27 | Cal 2 27 | Coronado 27 | Ericson 27 | Islander 27 | Niagara 26 | |
|---|---|---|---|---|---|---|
| Dimensions | ||||||
| LOA | 26.7 | 26.6 | 26.7 | 26.8 | 26.6 | 26.7 |
| LWL | 21.5 | 22.1 | 22.0 | 20.5 | 20.0 | 23.0 |
| Beam | 8.0 | 9.3 | 8.5 | 9.0 | 8.0 | 8.3 |
| Displacement | 6 | 6 | 6 | 6 | 4 | 4 |
| Ballast | 2 | 3 | 2 | 2 | 1 | 1 |
| Sail Area | — | 374 | 302 | 323 | 325 | 316 |
| Performance | ||||||
| PHRF | — | — | 231 | 207 | 228 | 188 |
| SA/Disp | — | 16.9 | 14.3 | 14.7 | 20.4 | 20.1 |
| Bal/Disp | 45.4 | 46.3 | 40.8 | 43.9 | 41.5 | — |
| Comfort | 25.6 | 22.8 | 23.9 | 24.4 | 18.1 | 15.2 |
| Capsize | 1.75 | 1.97 | 1.85 | 1.92 | 2.00 | 2.10 |
| Hull Speed | 6.2 | 6.3 | 6.3 | 6.1 | 6.0 | 6.4 |