The Southerly 430 is moderately powered for comfortable coastal cruising, with a steady, comfortable ride offshore.
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 36.5′, the Southerly 430 tops out around 8.1 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √36.5′ LWL = 8.1 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
14.9
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
32.4%
Typical cruising ballast — balanced stability and motion underway.
Displacement / Length
230
Moderate — a good balance of speed and load-carrying ability.
Comfort Ratio
32.5
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.81
Below the 2.0 offshore threshold — acceptable for ocean passages.
Pounds/Inch Immersion
1lbs
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
32.5
Good offshore comfort — steady enough for multi-day passages.
Under 20 — Snappy, racing motion
20–30 — Acceptable coastal
30–40 — Good offshore comfort
Over 40 — Very comfortable offshore
Capsize Screening Formula
1.81
Below the 2.0 offshore threshold — acceptable for ocean passages.
Under 2.0 — Acceptable for offshore
Over 2.0 — Coastal / protected waters
PHRF Fleet Position
Where the Southerly 430 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Racer 0–90
Cruiser/Racer 90–150
X 412
63s/nm
Hylas 42
87s/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° |
3.0 |
3.8 |
4.3 |
4.5 |
| Close Reach60° |
3.7 |
4.6 |
5.2 |
5.4 |
| Beam Reach90° |
4.5 |
5.7 |
6.3 |
6.6 |
| Broad Reach120–135° |
4.1 |
5.2 |
5.9 |
6.1 |
| Run150–180° |
3.3 |
4.2 |
4.7 |
4.9 |
These are simplified estimates based on hull speed (8.1 kts),
SA/D (14.9), 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 Southerly 430 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–7 kts
7–20 kts
20–28 kts
28+ kts
Ghosting
0–7 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
7–20 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
20–28 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
28+ 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 Southerly 430.
|
Southerly 430 |
Hylas 42 |
Nordship 40 Ds |
Oceanis 423 Beneteau |
Ovni 43 |
X 412 |
| Dimensions |
| LOA |
42.2 |
42.1 |
42.3 |
42.3 |
42.3 |
42.3 |
| LWL |
36.5 |
33.5 |
35.4 |
36.1 |
34.1 |
34.3 |
| Beam |
13.2 |
13.0 |
13.5 |
13.8 |
14.1 |
12.8 |
| Displacement |
25 |
17 |
23 |
21 |
18 |
16 |
| Ballast |
8 |
8 |
8 |
7 |
7 |
7 |
| Sail Area |
792 |
826 |
937 |
829 |
968 |
831 |
| Performance |
| PHRF |
— |
87 |
— |
— |
— |
63 |
| SA/Disp |
14.9 |
19.6 |
18.5 |
17.1 |
22.0 |
20.8 |
| Bal/Disp |
32.4 |
50.0 |
36.2 |
35.7 |
42.4 |
— |
| Comfort |
32.5 |
24.8 |
30.0 |
26.5 |
23.3 |
22.9 |
| Capsize |
1.81 |
2.00 |
1.89 |
1.98 |
2.13 |
2.03 |
| Hull Speed |
8.1 |
7.8 |
8.0 |
8.1 |
7.8 |
7.8 |