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Mariah 31
Designer: Henry Morschadt  ·  Builder: Pacific Seacraft  ·  First built: 1977
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About the Mariah 31

Designed by Henry Morschadt and built by Pacific Seacraft from 1977 to 1983, this traditionally-styled cruiser represents classic 1970s offshore sailing design philosophy. With only 89 hulls produced during its six-year production run, the Mariah 31 has become a sought-after example of quality fiberglass construction from one of the West Coast's most respected builders. The boat's substantial 16,000-pound displacement and generous 6,000-pound ballast provide the stability and seaworthiness that made Pacific Seacraft famous among serious cruising sailors. Her long keel configuration with transom-hung rudder delivers predictable tracking and self-steering capabilities highly valued for offshore passages, though at some cost to maneuverability in tight quarters. Rigged as a cutter with 656 square feet of working sail area, she offers excellent sail handling options for varying conditions. The cutter rig's versatility shines in heavy weather, allowing crews to balance the boat effectively with different sail combinations. Her impressive 36.75 comfort ratio and conservative 1.7 capsize screening value clearly position this design for serious offshore cruising rather than coastal day sailing. The Mariah 31 appeals to sailors prioritizing seaworthiness and traditional sailing characteristics over speed or spaciousness.

Core Dimensions
LOA (Length Overall) 37.00 ft / 11.28 m
LWL (Waterline Length) 25.00 ft / 7.62 m
Beam 10.71 ft / 3.26 m
Max Draft 4.42 ft / 1.35 m
Displacement 16,000.00 lb / 7,257 kg
Ballast 6,000.00 lb / 2,722 kg
Sail Area (Reported) 656.00 ft² / 60.94 m²
Headroom 6.42 ft / 1.96 m
Design & Construction
Hull Type Long keel w/trans. hung rudder
Rigging Type Cutter
Construction FG
Designer Henry Morschadt
Builder Pacific Seacraft
First Built 1977
Last Built 1983
Number Built 89
Related Sailboats Pacific Seacraft 37 · Valiant 37 · Endeavour 37 · Passport 37 · Oyster 37
Owner Reviews

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Performance Ratios
PHRF Rating PHRF (Performance Handicap Racing Fleet) is a national racing handicap measured in seconds per nautical mile. Lower values indicate faster boats. Ratings are sourced from US Sailing's national database (median across 60+ regional fleets).
Under 0 — Ultralight racer0–90 — Performance racer90–150 — Cruiser/racer150–210 — Typical cruiserOver 210 — Heavy/slow cruiser
 222
SA/Displacement Sail Area to Displacement ratio measures how much sail power a boat has relative to its weight. Higher values mean more performance and speed.
Under 14 — Heavy cruiser, slow14–18 — Cruising sailboat18–22 — Cruiser/racerOver 22 — Performance racer
 16.59
Ballast/Displacement Ballast to Displacement ratio shows what percentage of the boat's total weight is ballast. Higher values generally mean better initial stability and stiffer sail carrying.
30–35% — Typical cruiser35–45% — Stiff performance boatOver 45% — Racing oriented
 37.5
Displacement/Length Displacement to Length ratio measures how heavy a boat is relative to its waterline length. Lower values mean a lighter, faster boat.
Under 100 — Ultralight racer100–200 — Light cruiser/racer200–300 — Moderate cruiser300–400 — Heavy cruiserOver 400 — Very heavy
 457.14
Comfort Ratio Ted Brewer's Comfort Ratio predicts how comfortable a boat will feel in offshore conditions. Higher values mean a steadier, more comfortable motion in a seaway.
Under 20 — Uncomfortably rough20–30 — Acceptable coastal30–40 — Good offshore comfortOver 40 — Very comfortable offshore
 36.75
Capsize Screening Formula The USHS Capsize Screening Formula estimates offshore capsize risk. Lower is safer — values under 2.0 are considered acceptable for offshore sailing.
Under 2.0 — Safe for offshore2.0–2.2 — Borderline offshoreOver 2.2 — Coastal use recommended
 1.7
Hull Speed Hull Speed is the theoretical maximum speed of a displacement hull, calculated from waterline length. Most cruising sailboats reach this speed in moderate conditions. 6.70 kn
S# (Speed Number) The Speed Number (S#) is a quick performance index. Higher values indicate a faster, more powerful design relative to its size.
Under 3.0 — Slow cruiser3.0–5.0 — Average cruiser5.0–7.0 — Performance cruiserOver 7.0 — Racer
 0.78
Pounds/Inch Immersion Pounds per Inch Immersion (PPI) tells you how much weight is needed to sink the boat one inch. Useful for calculating how additional gear and stores affect waterline. 956.70 pounds/inch
SA/Displacement (Calc) Calculated Sail Area to Displacement ratio using actual measured sail dimensions rather than reported values. More precise than the reported SA/Disp figure. 14.57
Rig Dimensions
I (Foretriangle Height) 41.56 ft / 12.67 m
J (Foretriangle Base) 15.42 ft / 4.70 m
P (Mainsail Luff) 36.50 ft / 11.13 m
E (Mainsail Foot) 14.00 ft / 4.27 m
SA Fore 320.43 ft² / 29.77 m²
SA Main 255.50 ft² / 23.74 m²
SA Total (100%) 575.93 ft² / 53.51 m²
Est. Forestay Length 44.33 ft / 13.51 m
Engine & Accommodations
Fuel Capacity 35 gals / 132 L
Water Capacity 70 gals / 265 L
How It Compares

vs. Endeavour 37, Oyster 37, Pacific Seacraft 37, Passport 37, Valiant 37

This boat Similar boats
Dimensions
LOA
Mariah 31 ★
37.0 ft
Endeavour 37
37.0 ft
Oyster 37
37.0 ft
Pacific Seacraft 37
36.9 ft
Passport 37
37.0 ft
Valiant 37
37.0 ft
LWL
Mariah 31 ★
25.0 ft
Endeavour 37
30.0 ft
Oyster 37
31.2 ft
Pacific Seacraft 37
27.8 ft
Passport 37
29.6 ft
Valiant 37
31.6 ft
Beam
Mariah 31 ★
10.7 ft
Endeavour 37
11.6 ft
Oyster 37
12.1 ft
Pacific Seacraft 37
10.8 ft
Passport 37
11.9 ft
Valiant 37
11.5 ft
Displacement
Mariah 31 ★
16 lbs
Endeavour 37
20 lbs
Oyster 37
16 lbs
Pacific Seacraft 37
16 lbs
Passport 37
17 lbs
Valiant 37
17 lbs
Ballast
Mariah 31 ★
6 lbs
Endeavour 37
8 lbs
Oyster 37
7 lbs
Pacific Seacraft 37
6 lbs
Passport 37
6 lbs
Valiant 37
6 lbs
Sail Area
Mariah 31 ★
656 sq ft
Endeavour 37
—
Oyster 37
645 sq ft
Pacific Seacraft 37
618 sq ft
Passport 37
673 sq ft
Valiant 37
667 sq ft
Performance
PHRF Rating (lower = faster)
Mariah 31 ★
222 s/nm
Endeavour 37
174 s/nm
Oyster 37
140 s/nm
Pacific Seacraft 37
189 s/nm
Passport 37
138 s/nm
Valiant 37
—
SA / Displacement (higher = more powerful)
Mariah 31 ★
16.6
Endeavour 37
—
Oyster 37
16.0
Pacific Seacraft 37
15.6
Passport 37
16.1
Valiant 37
16.2
Ballast / Disp (higher = stiffer)
Mariah 31 ★
37.5 %
Endeavour 37
40.0 %
Oyster 37
44.0 %
Pacific Seacraft 37
—
Passport 37
—
Valiant 37
39.4 %
Comfort Ratio (higher = more comfortable offshore)
Mariah 31 ★
36.8
Endeavour 37
—
Oyster 37
28.1
Pacific Seacraft 37
34.0
Passport 37
31.1
Valiant 37
30.6
Capsize Screening (lower = safer)
Mariah 31 ★
1.70
Endeavour 37
—
Oyster 37
1.90
Pacific Seacraft 37
1.72
Passport 37
1.84
Valiant 37
1.79
Displacement / Length (lower = lighter)
Mariah 31 ★
457
Endeavour 37
330
Oyster 37
243
Pacific Seacraft 37
—
Passport 37
—
Valiant 37
240
Hull Speed
Mariah 31 ★
6.7 kts
Endeavour 37
—
Oyster 37
7.5 kts
Pacific Seacraft 37
7.1 kts
Passport 37
7.3 kts
Valiant 37
7.5 kts
Speed Number (higher = faster)
Mariah 31 ★
0.8
Endeavour 37
—
Oyster 37
2.1
Pacific Seacraft 37
1.4
Passport 37
1.7
Valiant 37
2.2
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