The Oday 31 is moderately powered for comfortable coastal cruising, with acceptable motion comfort for coastal passages, 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 25.6′, the Oday 31 tops out around 6.8 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √25.6′ LWL = 6.8 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
171s/nm
Typical cruiser — designed for comfort and ease, not podium finishes.
SA / Displacement
15.0
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
37.6%
Typical cruising ballast — balanced stability and motion underway.
Displacement / Length
269
Moderate-heavy — carries provisions well, deliberate in light air.
Comfort Ratio
24.5
Acceptable coastal comfort — fine for weekends, notice the chop offshore.
Capsize Screening
1.99
Below the 2.0 offshore threshold — acceptable for ocean passages.
Pounds/Inch Immersion
983lbs
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
24.5
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
1.99
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 Oday 31 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Racer 0–90
Cruiser/Racer 90–150
Cruiser 150–210
Capri 30 Catalina
111s/nm
J/30
144s/nm
Oday 31
171s/nm
Typical cruiser — designed for comfort and ease, not podium finishes.
Hunter 30 2
186s/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 |
3.2 |
3.6 |
3.7 |
| Close Reach60° |
3.1 |
3.9 |
4.3 |
4.5 |
| Beam Reach90° |
3.8 |
4.8 |
5.3 |
5.6 |
| Broad Reach120–135° |
3.5 |
4.4 |
4.9 |
5.1 |
| Run150–180° |
2.8 |
3.5 |
3.9 |
4.1 |
These are simplified estimates based on hull speed (6.8 kts),
SA/D (15.0), 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 Oday 31 — 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 Oday 31.
|
Oday 31 |
Cal 3 30 |
Capri 30 Catalina |
Hunter 30 2 |
J/30 |
Newport 30 3 |
| Dimensions |
| LOA |
30.1 |
30.1 |
30.0 |
30.1 |
30.0 |
30.0 |
| LWL |
25.6 |
26.3 |
25.0 |
25.8 |
25.0 |
26.5 |
| Beam |
10.8 |
10.2 |
10.8 |
11.0 |
10.8 |
10.7 |
| Displacement |
10 |
10 |
8 |
10 |
6 |
8 |
| Ballast |
3 |
5 |
3 |
3 |
2 |
2 |
| Sail Area |
436 |
474 |
387 |
433 |
436 |
— |
| Performance |
| PHRF |
171 |
— |
111 |
186 |
144 |
— |
| SA/Disp |
15.0 |
15.9 |
15.5 |
14.5 |
20.8 |
— |
| Bal/Disp |
37.6 |
47.6 |
37.5 |
36.2 |
39.3 |
30.6 |
| Comfort |
24.5 |
26.9 |
12.0 |
24.6 |
23.6 |
— |
| Capsize |
1.99 |
1.86 |
2.62 |
2.01 |
1.73 |
— |
| Hull Speed |
6.8 |
6.9 |
6.6 |
6.8 |
7.6 |
— |