The Marstrom 20 is with a quick, snappy motion best suited to day sailing.
Hull Speed
The theoretical displacement-mode speed limit — determined by waterline length, not engine or sail power.
5.7 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 18.0′, the Marstrom 20 tops out around 5.7 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √18.0′ LWL = 5.7 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
19
Ultralight — responsive and fast, but carries less stores.
Comfort Ratio
1.0
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
6.32
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Hull Speed
5.7kts
Pounds/Inch Immersion
4lbs
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
1.0
Quick, snappy motion — better for day sails and racing than long passages.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
6.32
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
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 Marstrom 20.
| Marstrom 20 | Astus 201 | Com-Pac Horizon Cat | Hobie Fox | Nacra 20 | Tornado Catamaran | |
|---|---|---|---|---|---|---|
| Dimensions | ||||||
| LOA | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 |
| LWL | 18.0 | 19.2 | 17.8 | — | — | — |
| Beam | 10.0 | 12.7 | 8.3 | 8.5 | 8.5 | 10.0 |
| Displacement | 254 | 838 | 2 | 419 | 390 | 300 |
| Ballast | — | — | 900 | — | — | — |
| Sail Area | — | — | 192 | 146 | — | 235 |
| Performance | ||||||
| SA/Disp | — | 58.2 | 16.7 | 41.8 | — | — |
| Bal/Disp | — | — | 36.0 | — | — | — |
| Comfort | 1.0 | 2.2 | 12.4 | 2.1 | 1.9 | 1.2 |
| Capsize | 6.32 | 5.41 | 2.46 | 4.55 | 4.66 | 5.98 |
| Hull Speed | 5.7 | 5.9 | 5.7 | 5.5 | 5.5 | 5.5 |