The S2 91 Sd is well-powered with enough sail area to move in light air, with acceptable motion comfort for coastal passages.
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 S2 91 Sd 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
19.9
Powerful cruiser/racer — quick in light air, reef early when it pipes up.
Comfort Ratio
20.0
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
2.12
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
938lbs
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
20.0
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
2.12
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 S2 91 Sd sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
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° |
2.9 |
3.7 |
4.1 |
4.3 |
| Close Reach60° |
3.5 |
4.4 |
4.9 |
5.1 |
| Beam Reach90° |
4.3 |
5.4 |
6.1 |
6.3 |
| Broad Reach120–135° |
4.0 |
5.0 |
5.6 |
5.8 |
| Run150–180° |
3.2 |
4.0 |
4.5 |
4.7 |
These are simplified estimates based on hull speed (6.7 kts),
SA/D (19.9), 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 S2 91 Sd — 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 S2 91 Sd.
|
S2 91 Sd |
J30 |
Pearson 30 |
S2 91 |
S2 91 Se |
S2 91 Sm |
| Dimensions |
| LOA |
29.8 |
29.8 |
29.8 |
29.8 |
29.8 |
29.8 |
| LWL |
25.0 |
25.0 |
25.0 |
25.0 |
25.8 |
25.0 |
| Beam |
10.5 |
11.2 |
9.5 |
10.5 |
10.5 |
10.5 |
| Displacement |
7 |
7 |
8 |
7 |
7 |
7 |
| Ballast |
— |
2 |
3 |
3 |
— |
— |
| Sail Area |
490 |
444 |
445 |
490 |
— |
444 |
| Performance |
| PHRF |
— |
— |
174 |
— |
— |
— |
| SA/Disp |
19.9 |
19.5 |
17.4 |
19.9 |
— |
18.0 |
| Bal/Disp |
— |
— |
42.8 |
40.8 |
— |
— |
| Comfort |
20.0 |
16.4 |
24.3 |
20.0 |
— |
20.0 |
| Capsize |
2.12 |
2.34 |
1.88 |
2.12 |
— |
2.12 |
| Hull Speed |
6.7 |
6.7 |
6.7 |
6.7 |
— |
6.7 |