The Oyster 625 is moderately powered for comfortable coastal cruising, 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 56.6′, the Oyster 625 tops out around 10.1 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √56.6′ LWL = 10.1 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
17.5
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
29.8%
Light ballast — tends to be tender; reef earlier than the numbers suggest.
Displacement / Length
182
Moderate — a good balance of speed and load-carrying ability.
Comfort Ratio
41.9
Very comfortable in a seaway — a genuine bluewater motion.
Capsize Screening
1.70
Below the 2.0 offshore threshold — acceptable for ocean passages.
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
41.9
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
1.70
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° |
4.1 |
5.1 |
5.7 |
6.0 |
| Close Reach60° |
4.9 |
6.2 |
6.9 |
7.2 |
| Beam Reach90° |
6.0 |
7.6 |
8.5 |
9.2 |
| Broad Reach120–135° |
5.6 |
7.0 |
7.9 |
8.5 |
| Run150–180° |
4.5 |
5.6 |
6.3 |
6.6 |
These are simplified estimates based on hull speed (10.1 kts),
SA/D (17.5), 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 625 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–7 kts
7–18 kts
18–26 kts
26+ kts
Ghosting
0–7 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
7–18 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 Oyster 625.
|
Oyster 625 |
Hylas 63 |
Hylas 70 |
Oyster 575 |
Oyster 655 |
| Dimensions |
| LOA |
62.4 |
63.0 |
69.7 |
59.0 |
67.6 |
| LWL |
56.6 |
57.8 |
61.6 |
51.5 |
59.5 |
| Beam |
17.8 |
17.7 |
18.0 |
16.4 |
18.4 |
| Displacement |
73 |
73 |
75 |
61 |
85 |
| Ballast |
22 |
28 |
28 |
17 |
— |
| Sail Area |
1,921 |
2 |
2 |
2,097 |
2 |
| Performance |
| SA/Disp |
17.5 |
18.9 |
21.7 |
21.5 |
17.6 |
| Bal/Disp |
29.8 |
38.8 |
38.5 |
28.9 |
— |
| Comfort |
41.9 |
41.7 |
38.4 |
42.4 |
44.0 |
| Capsize |
1.70 |
1.68 |
1.71 |
1.66 |
1.67 |
| Hull Speed |
10.1 |
10.2 |
10.5 |
9.6 |
10.3 |