The Lapworth 39 is modestly canvassed and unhurried, with a steady, comfortable ride offshore, designed for cruising comfort rather than racing.
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 30.9′, the Lapworth 39 tops out around 7.5 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √30.9′ LWL = 7.4 kts
Performance Ratios
Racing handicap, sail-carrying power, stability and comfort — and what each one actually tells you about a day on the water.
PHRF Rating
150s/nm
Typical cruiser — designed for comfort and ease, not podium finishes.
SA / Displacement
13.5
Modestly canvassed — a comfortable, unhurried cruiser.
Comfort Ratio
33.4
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.71
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
33.4
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
1.71
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 Lapworth 39 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Racer 0–90
Cruiser/Racer 90–150
Cruiser 150–210
Ericson 39
111s/nm
Lapworth 39
150s/nm
Typical cruiser — designed for comfort and ease, not podium finishes.
Bristol 39
168s/nm
Pearson 390
173s/nm
Columbia 38
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° |
2.7 |
3.4 |
3.8 |
3.9 |
| Close Reach60° |
3.2 |
4.1 |
4.6 |
4.8 |
| Beam Reach90° |
4.0 |
5.0 |
5.6 |
5.8 |
| Broad Reach120–135° |
3.7 |
4.6 |
5.2 |
5.4 |
| Run150–180° |
2.9 |
3.7 |
4.1 |
4.3 |
These are simplified estimates based on hull speed (7.5 kts),
SA/D (13.5), 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 Lapworth 39 — based on sail area, ballast, and displacement characteristics.
Ghost
Sweet Spot
Reef
Heavy
0–8 kts
8–22 kts
22–30 kts
30+ kts
Ghosting
0–8 kts
Light air, motor-sailing likely. Need patience and a light genoa.
Sweet Spot
8–22 kts
Comfortable under full sail. Best speed-to-comfort ratio.
Time to Reef
22–30 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 Lapworth 39.
|
Lapworth 39 |
Bristol 39 |
Cal 39 Mk Ii 1 147 |
Columbia 38 |
Ericson 39 |
Pearson 390 |
| Dimensions |
| LOA |
39.0 |
39.0 |
39.0 |
38.9 |
39.0 |
39.0 |
| LWL |
30.9 |
27.5 |
32.1 |
25.8 |
30.0 |
33.7 |
| Beam |
11.2 |
10.8 |
12.0 |
10.7 |
11.3 |
13.0 |
| Displacement |
18 |
17 |
17 |
14 |
19 |
20 |
| Ballast |
— |
6 |
7 |
6 |
9 |
7 |
| Sail Area |
576 |
648 |
719 |
650 |
737 |
663 |
| Performance |
| PHRF |
150 |
168 |
— |
180 |
111 |
173 |
| SA/Disp |
13.5 |
15.4 |
17.5 |
18.0 |
16.6 |
14.2 |
| Bal/Disp |
— |
37.0 |
41.2 |
45.7 |
50.0 |
36.4 |
| Comfort |
33.4 |
37.1 |
28.1 |
31.1 |
35.4 |
29.7 |
| Capsize |
1.71 |
1.66 |
1.87 |
1.77 |
1.70 |
1.90 |
| Hull Speed |
7.5 |
7.0 |
7.6 |
6.8 |
7.3 |
7.8 |