The Mariah 31 is moderately powered for comfortable coastal cruising, with a steady, comfortable ride offshore.
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 25.0′, the Mariah 31 tops out around 6.7 knots in displacement mode — after that, the bow wave outruns the hull and resistance climbs steeply.
1.34 × √25.0′ LWL = 6.7 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
222s/nm
Heavy or slow cruiser — all about the journey, not the elapsed time.
SA / Displacement
16.6
Moderate sail power — a capable coastal cruiser, not overpowered.
Ballast / Displacement
37.5%
Typical cruising ballast — balanced stability and motion underway.
Displacement / Length
457
Heavy displacement — a slow, steady, seakindly hull.
Comfort Ratio
36.8
Good offshore comfort — steady enough for multi-day passages.
Capsize Screening
1.70
Below the 2.0 offshore threshold — acceptable for ocean passages.
SA/Disp (Calculated)
14.6
Computed from measured I/J/P/E rather than reported sail area.
Pounds/Inch Immersion
957lbs
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
36.8
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
1.70
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 Mariah 31 sits on the PHRF handicap spectrum — lower numbers mean faster boats.
Cruiser/Racer 90–150
Cruiser 150–210
Heavy Cruiser 210–300
Passport 37
138s/nm
Oyster 37
140s/nm
Endeavour 37
174s/nm
Pacific Seacraft 37
189s/nm
Mariah 31
222s/nm
Heavy or slow cruiser — all about the journey, not the elapsed time.
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° |
2.6 |
3.3 |
3.7 |
3.9 |
| Close Reach60° |
3.2 |
4.0 |
4.5 |
4.7 |
| Beam Reach90° |
3.9 |
4.9 |
5.5 |
5.8 |
| Broad Reach120–135° |
3.6 |
4.6 |
5.1 |
5.3 |
| Run150–180° |
2.9 |
3.7 |
4.1 |
4.3 |
These are simplified estimates based on hull speed (6.7 kts),
SA/D (16.6), 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 Mariah 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 Mariah 31.
|
Mariah 31 |
Endeavour 37 |
Oyster 37 |
Pacific Seacraft 37 |
Passport 37 |
Valiant 37 |
| Dimensions |
| LOA |
37.0 |
37.0 |
37.0 |
36.9 |
37.0 |
37.0 |
| LWL |
25.0 |
30.0 |
31.2 |
27.8 |
29.6 |
31.6 |
| Beam |
10.7 |
11.6 |
12.1 |
10.8 |
11.9 |
11.5 |
| Displacement |
16 |
20 |
16 |
16 |
17 |
17 |
| Ballast |
6 |
8 |
7 |
6 |
6 |
6 |
| Sail Area |
656 |
574 |
645 |
618 |
673 |
667 |
| Performance |
| PHRF |
222 |
174 |
140 |
189 |
138 |
— |
| SA/Disp |
16.6 |
12.5 |
16.0 |
15.6 |
16.1 |
16.2 |
| Bal/Disp |
37.5 |
40.0 |
44.0 |
— |
— |
39.4 |
| Comfort |
36.8 |
36.9 |
28.1 |
34.0 |
31.1 |
30.6 |
| Capsize |
1.70 |
1.71 |
1.90 |
1.72 |
1.84 |
1.79 |
| Hull Speed |
6.7 |
7.3 |
7.5 |
7.1 |
7.3 |
7.5 |