The Tempest 31 Westerly is moderately powered for comfortable coastal cruising, 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 24.5′, the Tempest 31 Westerly tops out around 6.6 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √24.5′ LWL = 6.6 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
14.8
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
274
Moderate-heavy — carries provisions well, deliberate in light air.
Comfort Ratio
22.2
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
2.08
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
948lbs
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
22.2
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
2.08
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 Tempest 31 Westerly sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
Tanzer 31
165s/nm
Pearson 31 2
180s/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° |
2.5 |
3.1 |
3.5 |
3.6 |
| Close Reach60° |
3.0 |
3.8 |
4.2 |
4.4 |
| Beam Reach90° |
3.7 |
4.6 |
5.2 |
5.4 |
| Broad Reach120–135° |
3.4 |
4.3 |
4.8 |
5.0 |
| Run150–180° |
2.7 |
3.4 |
3.8 |
4.0 |
These are simplified estimates based on hull speed (6.6 kts),
SA/D (14.8), 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 Tempest 31 Westerly — 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 Tempest 31 Westerly.
|
Tempest 31 Westerly |
Etap 32I |
Oceanis 301 Beneteau |
Pearson 31 2 |
Regatta 310 Westerly |
Tanzer 31 |
| Dimensions |
| LOA |
30.6 |
30.7 |
30.5 |
30.7 |
30.6 |
30.6 |
| LWL |
24.5 |
26.3 |
26.3 |
25.4 |
24.5 |
25.0 |
| Beam |
10.8 |
11.2 |
10.8 |
10.7 |
10.8 |
10.5 |
| Displacement |
9 |
9 |
8 |
10 |
9 |
8 |
| Ballast |
2 |
2 |
3 |
3 |
2 |
3 |
| Sail Area |
400 |
588 |
430 |
493 |
— |
468 |
| Performance |
| PHRF |
— |
— |
— |
180 |
— |
165 |
| SA/Disp |
14.8 |
20.7 |
16.1 |
17.1 |
— |
18.3 |
| Bal/Disp |
29.8 |
29.4 |
35.0 |
38.0 |
29.8 |
39.8 |
| Comfort |
22.2 |
21.9 |
— |
24.5 |
— |
21.0 |
| Capsize |
2.08 |
2.10 |
— |
1.98 |
— |
2.08 |
| Hull Speed |
6.6 |
6.9 |
— |
6.8 |
— |
6.7 |