The Sj 30 Oyster is well-powered with enough sail area to move in light air, with a quick, snappy motion best suited to day sailing.
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 25.0′, the Sj 30 Oyster tops out around 6.7 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √25.0′ LWL = 6.7 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
18.9
Powerful cruiser/racer — quick in light air, reef early when it pipes up.
Comfort Ratio
16.0
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
2.31
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
960lbs
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
16.0
Quick, snappy motion — better for day sails and racing than long passages.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
2.31
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters
PHRF Fleet Position
Where the Sj 30 Oyster 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
Cape Dory 30 Mk Ii
192s/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° |
2.8 |
3.6 |
4.0 |
4.1 |
| Close Reach60° |
3.4 |
4.3 |
4.8 |
5.0 |
| Beam Reach90° |
4.2 |
5.3 |
5.9 |
6.1 |
| Broad Reach120–135° |
3.9 |
4.9 |
5.4 |
5.7 |
| Run150–180° |
3.1 |
3.9 |
4.4 |
4.5 |
These are simplified estimates based on hull speed (6.7 kts),
SA/D (18.9), 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 Sj 30 Oyster — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–6 kts
6–18 kts
18–26 kts
26+ kts
Ghosting
0–6 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
6–18 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 Sj 30 Oyster.
|
Sj 30 Oyster |
Cape Dory 30 Mk Ii |
First 305 Beneteau |
Maestro 31 |
Nonsuch 30 |
Oceanis 301 Beneteau |
| Dimensions |
| LOA |
30.4 |
30.5 |
30.5 |
30.5 |
30.3 |
30.5 |
| LWL |
25.0 |
24.2 |
26.8 |
23.6 |
28.8 |
26.3 |
| Beam |
10.8 |
10.5 |
10.5 |
10.2 |
11.9 |
10.8 |
| Displacement |
6 |
10 |
8 |
5 |
10 |
8 |
| Ballast |
2 |
4 |
2 |
2 |
4 |
3 |
| Sail Area |
410 |
495 |
410 |
— |
540 |
430 |
| Performance |
| PHRF |
— |
192 |
— |
— |
174 |
— |
| SA/Disp |
18.9 |
16.6 |
16.1 |
— |
18.1 |
16.1 |
| Bal/Disp |
— |
40.0 |
36.1 |
48.0 |
— |
35.0 |
| Comfort |
16.0 |
27.2 |
19.9 |
— |
20.5 |
— |
| Capsize |
2.31 |
1.92 |
2.08 |
— |
2.18 |
— |
| Hull Speed |
6.7 |
6.6 |
6.9 |
— |
7.2 |
— |