The Dark Harbor 12 12 is well-powered with enough sail area to move in light air, with acceptable motion comfort for coastal passages.
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 12.5′, the Dark Harbor 12 12 tops out around 4.7 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √12.5′ LWL = 4.7 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
SA / Displacement
21.2
Powerful cruiser/racer — quick in light air, reef early when it pipes up.
Displacement / Length
457
Heavy displacement — a slow, steady, seakindly hull.
Comfort Ratio
22.5
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
1.69
Below the 2.0 offshore threshold — acceptable for ocean passages.
Pounds/Inch Immersion
1lbs
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
22.5
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
1.69
Below the 2.0 offshore threshold — acceptable for ocean passages.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters
PHRF Fleet Position
Where the Dark Harbor 12 12 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
Highlander
191s/nm
Barnegat 20
228s/nm
Cal 20
258s/nm
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° |
2.1 |
2.7 |
3.0 |
3.1 |
| Close Reach60° |
2.6 |
3.2 |
3.6 |
3.8 |
| Beam Reach90° |
3.1 |
4.0 |
4.4 |
4.6 |
| Broad Reach120–135° |
2.9 |
3.7 |
4.1 |
4.3 |
| Run150–180° |
2.3 |
2.9 |
3.3 |
3.4 |
These are simplified estimates based on hull speed (4.7 kts),
SA/D (21.2), 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 Dark Harbor 12 12 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–6 kts
6–18 kts
18–26 kts
26+ kts
Ghosting
0–6 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
6–18 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
18–26 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
26+ 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 Dark Harbor 12 12.
|
Dark Harbor 12 12 |
Barnegat 20 |
C Scow |
Cal 20 |
Flying Fifteen |
Highlander |
| Dimensions |
| LOA |
20.2 |
20.1 |
20.0 |
20.0 |
20.0 |
20.0 |
| LWL |
12.5 |
18.0 |
— |
18.0 |
15.0 |
19.7 |
| Beam |
5.3 |
7.0 |
7.0 |
7.0 |
7.0 |
6.7 |
| Displacement |
2 |
1 |
650 |
1 |
725 |
830 |
| Ballast |
— |
— |
— |
900 |
372 |
— |
| Sail Area |
210 |
175 |
216 |
195 |
142 |
225 |
| Performance |
| PHRF |
— |
228 |
— |
258 |
— |
191 |
| SA/Disp |
21.2 |
23.0 |
46.1 |
20.0 |
28.2 |
40.8 |
| Bal/Disp |
— |
— |
— |
46.2 |
51.3 |
— |
| Comfort |
22.5 |
8.4 |
4.2 |
12.1 |
5.1 |
5.2 |
| Capsize |
1.69 |
2.54 |
3.23 |
2.24 |
3.12 |
2.84 |
| Hull Speed |
4.7 |
5.7 |
5.5 |
5.7 |
5.2 |
5.9 |