The Dehler 42 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 37.7′, the Dehler 42 tops out around 8.2 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √37.7′ LWL = 8.2 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
21.7
Powerful cruiser/racer — quick in light air, reef early when it pipes up.
Ballast / Displacement
33.0%
Typical cruising ballast — balanced stability and motion underway.
Displacement / Length
167
Moderate — a good balance of speed and load-carrying ability.
Comfort Ratio
26.3
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
1.89
Below the 2.0 offshore threshold — acceptable for ocean passages.
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
26.3
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
1.89
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 Dehler 42 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Racer 0–90
Cruiser/Racer 90–150
Dehler 39
75s/nm
Dehler 41 Ds
84s/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° |
3.7 |
4.7 |
5.2 |
5.5 |
| Close Reach60° |
4.5 |
5.7 |
6.3 |
6.6 |
| Beam Reach90° |
5.5 |
7.0 |
7.8 |
8.4 |
| Broad Reach120–135° |
5.1 |
6.4 |
7.2 |
7.8 |
| Run150–180° |
4.1 |
5.1 |
5.8 |
6.0 |
These are simplified estimates based on hull speed (8.2 kts),
SA/D (21.7), 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 Dehler 42 — 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 Dehler 42.
|
Dehler 42 |
Dehler 39 |
Dehler 41 Cr |
Dehler 41 Ds |
Dehler 46 C |
| Dimensions |
| LOA |
42.1 |
39.0 |
40.9 |
40.9 |
48.4 |
| LWL |
37.7 |
35.1 |
36.3 |
36.3 |
42.3 |
| Beam |
12.8 |
12.5 |
12.8 |
12.8 |
14.3 |
| Displacement |
20 |
15 |
19 |
19 |
24 |
| Ballast |
6 |
6 |
7 |
7 |
6 |
| Sail Area |
1 |
1,032 |
876 |
876 |
1 |
| Performance |
| PHRF |
— |
75 |
— |
84 |
— |
| SA/Disp |
21.7 |
26.7 |
19.3 |
19.3 |
26.1 |
| Bal/Disp |
33.0 |
42.1 |
37.1 |
37.1 |
28.1 |
| Comfort |
26.3 |
22.7 |
27.0 |
27.0 |
25.1 |
| Capsize |
1.89 |
2.02 |
1.90 |
1.90 |
1.96 |
| Hull Speed |
8.2 |
7.9 |
8.1 |
8.1 |
8.7 |