The Southerly 28 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.
6.6 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 24.0′, the Southerly 28 tops out around 6.6 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √24.0′ 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.
Displacement / Length
275
Moderate-heavy — carries provisions well, deliberate in light air.
Comfort Ratio
27.9
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
1.77
Below the 2.0 offshore threshold — acceptable for ocean passages.
Hull Speed
6.6kts
Pounds/Inch Immersion
772lbs
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
27.9
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
1.77
Below the 2.0 offshore threshold — acceptable for ocean passages.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters