The Thai Mk Iv 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.
5.1 kts
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
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
37
Ultralight — responsive and fast, but carries less stores.
Comfort Ratio
2.3
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
3.81
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Hull Speed
5.1kts
Pounds/Inch Immersion
2lbs
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
2.3
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
3.81
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
PHRF Fleet Position
Where the Thai Mk Iv sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Thistle
How It Compares
Side-by-side with the boats most often cross-shopped against the Thai Mk Iv.
| Thai Mk Iv | Harpoon 52 | Hobie 17 | Nacra 52 | Thistle | Tiger Cat | |
|---|---|---|---|---|---|---|
| Dimensions | ||||||
| LOA | 17.0 | 17.0 | 17.0 | 17.0 | 17.0 | 17.0 |
| LWL | — | 15.0 | — | — | 17.0 | 15.8 |
| Beam | 6.0 | 7.5 | 7.9 | 8.0 | 6.0 | 8.0 |
| Displacement | 250 | 565 | 315 | 350 | 515 | 585 |
| Sail Area | 220 | 160 | 168 | — | — | — |
| Performance | ||||||
| PHRF | — | — | — | — | 186 | — |
| SA/Disp | — | 37.5 | 58.1 | — | — | — |
| Comfort | 2.3 | 3.8 | — | 2.2 | — | 3.5 |
| Capsize | 3.81 | 3.63 | — | 4.54 | — | 3.81 |
| Hull Speed | 5.1 | 5.2 | — | 5.1 | — | 5.3 |