The Swan 70 is aggressively canvassed for its weight, 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 61.7′, the Swan 70 tops out around 10.5 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √61.7′ LWL = 10.5 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
24.6
Performance-oriented — carries a lot of canvas for its weight.
Ballast / Displacement
36.2%
Typical cruising ballast — balanced stability and motion underway.
Displacement / Length
126
Ultralight — responsive and fast, but carries less stores.
Comfort Ratio
35.2
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.74
Below the 2.0 offshore threshold — acceptable for ocean passages.
SA/Disp (Calculated)
25.2
Computed from measured I/J/P/E rather than reported sail area.
Pounds/Inch Immersion
3lbs
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
35.2
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
1.74
Below the 2.0 offshore threshold — acceptable for ocean passages.
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° |
5.0 |
6.3 |
7.0 |
7.3 |
| Close Reach60° |
6.0 |
7.6 |
8.5 |
8.8 |
| Beam Reach90° |
7.4 |
9.3 |
10.4 |
11.3 |
| Broad Reach120–135° |
6.8 |
8.6 |
9.6 |
10.4 |
| Run150–180° |
5.4 |
6.9 |
7.7 |
8.0 |
These are simplified estimates based on hull speed (10.5 kts),
SA/D (24.6), 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 Swan 70 — 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 Swan 70.
|
Swan 70 |
Baltic 73 |
Cnb 66 |
Oyster 675 |
Oyster 70 |
Swan 68 |
| Dimensions |
| LOA |
70.1 |
73.2 |
67.6 |
69.1 |
70.0 |
67.7 |
| LWL |
61.7 |
60.7 |
60.5 |
60.1 |
58.0 |
54.7 |
| Beam |
17.5 |
18.0 |
18.1 |
18.5 |
17.3 |
17.8 |
| Displacement |
66 |
77 |
68 |
82 |
91 |
88 |
| Ballast |
23 |
29 |
20 |
— |
24 |
35 |
| Sail Area |
2 |
2 |
2 |
— |
2 |
— |
| Performance |
| SA/Disp |
24.6 |
22.0 |
22.2 |
— |
23.8 |
— |
| Bal/Disp |
36.2 |
38.6 |
30.1 |
— |
— |
40.0 |
| Comfort |
35.2 |
39.3 |
35.9 |
— |
51.5 |
— |
| Capsize |
1.74 |
1.70 |
1.77 |
— |
1.54 |
— |
| Hull Speed |
10.5 |
10.4 |
10.4 |
— |
10.2 |
— |