The Thumb 15 is aggressively canvassed for its weight, 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.
A displacement hull pushes a bow wave whose speed is limited by the waterline length.
With a waterline of 13.8′, the Thumb 15 tops out around 5.0 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √13.8′ LWL = 5.0 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
SA / Displacement
60.4
Performance-oriented — carries a lot of canvas for its weight.
Comfort Ratio
2.1
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
4.04
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
291lbs
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
2.1
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
4.04
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
Estimated Speed by Wind
Rough boat speed estimates at different true wind speeds and points of sail — derived from hull speed, SA/D, and displacement, not measured polars.
| Point of Sail |
6 kts TWS |
10 kts TWS |
15 kts TWS |
20 kts TWS |
| Close-hauled40–50° |
2.3 |
3.0 |
3.3 |
3.4 |
| Close Reach60° |
2.8 |
3.6 |
4.0 |
4.2 |
| Beam Reach90° |
3.5 |
4.4 |
4.9 |
5.0 |
| Broad Reach120–135° |
3.2 |
4.1 |
4.5 |
4.7 |
| Run150–180° |
2.6 |
3.2 |
3.6 |
3.8 |
These are simplified estimates based on hull speed (5.0 kts),
SA/D (60.4), and empirical efficiency curves — not instrument-measured
polars. Real-world speed varies with sea state, bottom condition, sail trim, and current.
Speeds in gold approach hull speed;
bold gold means near or at hull speed.
Wind Range & Comfort Envelope
Estimated wind ranges for comfortable sailing on the Thumb 15 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–5 kts
5–16 kts
16–24 kts
24+ kts
Ghosting
0–5 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
5–16 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
16–24 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
24+ kts
Storm conditions. Storm jib or bare poles. Seek shelter if coastal.
How It Compares
Side-by-side with the boats most often cross-shopped against the Thumb 15.
|
Thumb 15 |
Albacore |
Caprice 15 |
Mutineer 15 |
Precision 15 Cb |
Tasar |
| Dimensions |
| LOA |
14.8 |
15.0 |
14.7 |
15.0 |
15.0 |
14.8 |
| LWL |
13.8 |
14.8 |
— |
14.1 |
13.8 |
14.0 |
| Beam |
5.9 |
5.1 |
6.0 |
6.0 |
7.0 |
5.8 |
| Displacement |
200 |
240 |
250 |
410 |
390 |
141 |
| Sail Area |
129 |
125 |
123 |
150 |
130 |
123 |
| Performance |
| SA/Disp |
60.4 |
51.8 |
49.6 |
43.5 |
39.0 |
72.7 |
| Comfort |
2.1 |
2.9 |
2.7 |
4.1 |
3.2 |
1.5 |
| Capsize |
4.04 |
3.27 |
3.84 |
3.23 |
3.83 |
4.42 |
| Hull Speed |
5.0 |
5.2 |
4.7 |
5.0 |
5.0 |
5.0 |