The Cape Dory 30K is moderately powered for comfortable coastal cruising, with a steady, comfortable ride offshore.
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 22.8′, the Cape Dory 30K tops out around 6.4 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √22.8′ LWL = 6.4 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
PHRF Rating
228s/nm
Heavy or slow cruiser — all about the journey, not the elapsed time.
SA / Displacement
15.0
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
40.0%
Stiff enough to carry a big genoa comfortably into moderate breeze.
Displacement / Length
375
Heavy displacement — a slow, steady, seakindly hull.
Comfort Ratio
33.1
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.67
Below the 2.0 offshore threshold — acceptable for ocean passages.
SA/Disp (Calculated)
12.7
Computed from measured I/J/P/E rather than reported sail area.
Pounds/Inch Immersion
734lbs
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
33.1
Good offshore comfort — steady enough for multi-day passages.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
1.67
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 Cape Dory 30K sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
Nonsuch 30
174s/nm
Pearson 303
198s/nm
Cape Dory 30K
228s/nm
Heavy or slow cruiser — all about the journey, not the elapsed time.
Alberg 30
228s/nm
Westerly 30
231s/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° |
2.4 |
3.0 |
3.4 |
3.5 |
| Close Reach60° |
2.9 |
3.7 |
4.1 |
4.3 |
| Beam Reach90° |
3.6 |
4.5 |
5.0 |
5.3 |
| Broad Reach120–135° |
3.3 |
4.2 |
4.7 |
4.9 |
| Run150–180° |
2.6 |
3.3 |
3.7 |
3.9 |
These are simplified estimates based on hull speed (6.4 kts),
SA/D (15.0), 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 Cape Dory 30K — 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 Cape Dory 30K.
|
Cape Dory 30K |
Alberg 30 |
Nonsuch 30 |
Pearson 303 |
Wanderer 30 Pearson |
Westerly 30 |
| Dimensions |
| LOA |
30.2 |
30.3 |
30.3 |
30.3 |
30.3 |
30.2 |
| LWL |
22.8 |
21.7 |
28.8 |
25.4 |
23.3 |
25.8 |
| Beam |
9.0 |
8.8 |
11.9 |
10.9 |
9.3 |
8.7 |
| Displacement |
10 |
9 |
10 |
10 |
9 |
7 |
| Ballast |
4 |
3 |
4 |
3 |
3 |
3 |
| Sail Area |
434 |
410 |
540 |
459 |
— |
— |
| Performance |
| PHRF |
228 |
228 |
174 |
198 |
— |
231 |
| SA/Disp |
15.0 |
15.2 |
18.1 |
15.8 |
— |
— |
| Bal/Disp |
40.0 |
36.7 |
— |
34.7 |
38.8 |
44.0 |
| Comfort |
33.1 |
31.9 |
20.5 |
24.1 |
— |
— |
| Capsize |
1.67 |
1.69 |
2.18 |
2.02 |
— |
— |
| Hull Speed |
6.4 |
6.2 |
7.2 |
6.8 |
— |
— |