The Oyster 825 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 72.0′, the Oyster 825 tops out around 11.4 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √72.0′ LWL = 11.4 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
SA / Displacement
23.7
Performance-oriented — carries a lot of canvas for its weight.
Ballast / Displacement
30.4%
Typical cruising ballast — balanced stability and motion underway.
Displacement / Length
138
Ultralight — responsive and fast, but carries less stores.
Comfort Ratio
41.5
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
41.5
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
1.70
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° |
5.4 |
6.8 |
7.6 |
7.9 |
| Close Reach60° |
6.5 |
8.2 |
9.1 |
9.5 |
| Beam Reach90° |
7.9 |
10.0 |
11.2 |
12.2 |
| Broad Reach120–135° |
7.3 |
9.3 |
10.4 |
11.2 |
| Run150–180° |
5.9 |
7.4 |
8.3 |
8.6 |
These are simplified estimates based on hull speed (11.4 kts),
SA/D (23.7), 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 825 — 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 825.
|
Oyster 825 |
Challenge 72 |
Hylas 70 |
Oyster 625 |
Oyster 655 |
| Dimensions |
| LOA |
82.5 |
72.2 |
69.7 |
62.4 |
67.6 |
| LWL |
72.0 |
61.8 |
61.6 |
56.6 |
59.5 |
| Beam |
20.7 |
18.1 |
18.0 |
17.8 |
18.4 |
| Displacement |
115 |
83 |
75 |
73 |
85 |
| Ballast |
35 |
— |
28 |
22 |
— |
| Sail Area |
3,500 |
2,700 |
2 |
1,921 |
2 |
| Performance |
| SA/Disp |
23.7 |
22.6 |
21.7 |
17.5 |
17.6 |
| Bal/Disp |
30.4 |
— |
38.5 |
29.8 |
— |
| Comfort |
41.5 |
41.9 |
38.4 |
41.9 |
44.0 |
| Capsize |
1.70 |
1.65 |
1.71 |
1.70 |
1.67 |
| Hull Speed |
11.4 |
10.5 |
10.5 |
10.1 |
10.3 |