The Hb 31 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 23.6′, the Hb 31 tops out around 6.5 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √23.6′ LWL = 6.5 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
19.1
Powerful cruiser/racer — quick in light air, reef early when it pipes up.
Ballast / Displacement
48.1%
Race-oriented ballast ratio — very stiff and powerful.
Displacement / Length
187
Moderate — a good balance of speed and load-carrying ability.
Comfort Ratio
14.5
Quick, snappy motion — better for day sails and racing than long passages.
Capsize Screening
2.38
Above the 2.0 offshore threshold — best suited for coastal and protected waters.
Pounds/Inch Immersion
885lbs
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
14.5
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
2.38
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 Hb 31 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
Nicholson 31
194s/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° |
2.7 |
3.5 |
3.9 |
4.0 |
| Close Reach60° |
3.3 |
4.2 |
4.7 |
4.9 |
| Beam Reach90° |
4.1 |
5.1 |
5.8 |
6.2 |
| Broad Reach120–135° |
3.8 |
4.8 |
5.3 |
5.8 |
| Run150–180° |
3.0 |
3.8 |
4.3 |
4.4 |
These are simplified estimates based on hull speed (6.5 kts),
SA/D (19.1), 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 Hb 31 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–6 kts
6–20 kts
20–30 kts
30+ kts
Ghosting
0–6 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
6–20 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
20–30 kts
Time to shorten sail. Reef the main, swap to a working jib.
Heavy Weather
30+ 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 Hb 31.
|
Hb 31 |
Attalia 32 Jeanneau |
First 30 E Beneteau Berret |
First 305 Beneteau |
Nicholson 31 |
Tanzer 31 |
| Dimensions |
| LOA |
30.5 |
30.5 |
30.5 |
30.5 |
30.5 |
30.6 |
| LWL |
23.6 |
25.9 |
27.0 |
26.8 |
24.2 |
25.0 |
| Beam |
10.5 |
10.8 |
10.7 |
10.5 |
10.2 |
10.5 |
| Displacement |
5 |
7 |
7 |
8 |
13 |
8 |
| Ballast |
2 |
2 |
2 |
2 |
4 |
3 |
| Sail Area |
370 |
410 |
392 |
410 |
484 |
468 |
| Performance |
| PHRF |
— |
— |
— |
— |
194 |
165 |
| SA/Disp |
19.1 |
17.2 |
17.1 |
16.1 |
14.1 |
18.3 |
| Bal/Disp |
48.1 |
39.0 |
40.6 |
36.1 |
— |
39.8 |
| Comfort |
14.5 |
17.8 |
16.6 |
19.9 |
35.0 |
21.0 |
| Capsize |
2.38 |
2.22 |
2.23 |
2.08 |
1.74 |
2.08 |
| Hull Speed |
6.5 |
6.8 |
7.0 |
6.9 |
6.6 |
6.7 |