The Oyster 70 is aggressively canvassed for its weight, with a gentle bluewater motion.
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 58.0′, the Oyster 70 tops out around 10.2 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √58.0′ LWL = 10.2 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
23.8
Performance-oriented — carries a lot of canvas for its weight.
Comfort Ratio
51.5
Very comfortable in a seaway — a genuine bluewater motion.
Capsize Screening
1.54
Below the 2.0 offshore threshold — acceptable for ocean passages.
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
51.5
Very comfortable in a seaway — a genuine bluewater motion.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
1.54
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° |
4.8 |
6.1 |
6.8 |
7.1 |
| Close Reach60° |
5.8 |
7.4 |
8.2 |
8.6 |
| Beam Reach90° |
7.1 |
9.0 |
10.1 |
10.2 |
| Broad Reach120–135° |
6.6 |
8.3 |
9.3 |
9.7 |
| Run150–180° |
5.3 |
6.7 |
7.4 |
7.8 |
These are simplified estimates based on hull speed (10.2 kts),
SA/D (23.8), 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 Oyster 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 Oyster 70.
|
Oyster 70 |
Baltic 73 |
Cnb 66 |
Oyster 675 |
Swan 68 |
Swan 70 |
| Dimensions |
| LOA |
70.0 |
73.2 |
67.6 |
69.1 |
67.7 |
70.1 |
| LWL |
58.0 |
60.7 |
60.5 |
60.1 |
54.7 |
61.7 |
| Beam |
17.3 |
18.0 |
18.1 |
18.5 |
17.8 |
17.5 |
| Displacement |
91 |
77 |
68 |
82 |
88 |
66 |
| Ballast |
24 |
29 |
20 |
— |
35 |
23 |
| Sail Area |
2 |
2 |
2 |
— |
— |
2 |
| Performance |
| SA/Disp |
23.8 |
22.0 |
22.2 |
— |
— |
24.6 |
| Bal/Disp |
— |
38.6 |
30.1 |
— |
40.0 |
36.2 |
| Comfort |
51.5 |
39.3 |
35.9 |
— |
— |
35.2 |
| Capsize |
1.54 |
1.70 |
1.77 |
— |
— |
1.74 |
| Hull Speed |
10.2 |
10.4 |
10.4 |
— |
— |
10.5 |