The Sunspot 15 is moderately powered for comfortable coastal cruising, 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 13.5′, the Sunspot 15 tops out around 4.9 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √13.5′ LWL = 4.9 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
17.9
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
44.4%
Stiff enough to carry a big genoa comfortably into moderate breeze.
Displacement / Length
165
Moderate — a good balance of speed and load-carrying ability.
Comfort Ratio
8.7
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
2.58
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
SA/Disp (Calculated)
16.6
Computed from measured I/J/P/E rather than reported sail area.
Pounds/Inch Immersion
299lbs
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
8.7
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
2.58
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° |
2.0 |
2.5 |
2.8 |
3.0 |
| Close Reach60° |
2.4 |
3.1 |
3.4 |
3.6 |
| Beam Reach90° |
3.0 |
3.8 |
4.2 |
4.6 |
| Broad Reach120–135° |
2.7 |
3.5 |
3.9 |
4.2 |
| Run150–180° |
2.2 |
2.8 |
3.1 |
3.2 |
These are simplified estimates based on hull speed (4.9 kts),
SA/D (17.9), 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 Sunspot 15 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–7 kts
7–22 kts
22–32 kts
32+ kts
Ghosting
0–7 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
7–22 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
22–32 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
32+ 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 Sunspot 15.
|
Sunspot 15 |
Commodore 15 |
Montgomery 15 |
Mutineer 15 |
Precision 15 K |
West Wight Potter 15 |
| Dimensions |
| LOA |
15.1 |
15.0 |
15.0 |
15.0 |
15.0 |
15.0 |
| LWL |
13.5 |
14.4 |
13.0 |
14.1 |
13.8 |
11.8 |
| Beam |
6.2 |
5.8 |
5.5 |
6.0 |
7.0 |
5.5 |
| Displacement |
900 |
270 |
475 |
410 |
600 |
475 |
| Ballast |
400 |
— |
175 |
— |
250 |
165 |
| Sail Area |
104 |
109 |
90 |
150 |
— |
— |
| Performance |
| SA/Disp |
17.9 |
42.1 |
23.6 |
43.5 |
— |
— |
| Bal/Disp |
44.4 |
— |
36.8 |
— |
41.7 |
34.7 |
| Comfort |
8.7 |
2.7 |
5.5 |
4.1 |
— |
— |
| Capsize |
2.58 |
3.60 |
2.82 |
3.23 |
— |
— |
| Hull Speed |
4.9 |
5.1 |
4.8 |
5.0 |
— |
— |