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Inferno 31
Designer: Håkan Södergren  ·  Builder: Finngulf  ·  First built: 1983
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About the Inferno 31

With limited documentation available, the Inferno 31 represents one of those intriguing sailboats that exists somewhat in the shadows of sailing history. This 31-foot vessel appears to have been designed during an era when builders were experimenting with performance-oriented designs for the growing recreational sailing market. Based on the naming convention and size class, the Inferno 31 likely falls into the sport cruiser category, designed to offer spirited sailing performance while maintaining reasonable accommodations for weekend cruising or coastal adventures. The "Inferno" moniker suggests a boat built with speed and excitement in mind, rather than heavy cruising comfort. Without comprehensive specifications readily available, prospective buyers should approach this model with thorough pre-purchase research and professional survey work. The limited documentation could indicate either a smaller production run or a boat that didn't achieve widespread market penetration, which sometimes creates opportunities for savvy buyers seeking unique vessels. For sailors drawn to less common designs, the Inferno 31 might offer an interesting alternative to mainstream production boats, though the scarcity of readily available information underscores the importance of careful evaluation and expert consultation before making any purchase decisions.

Core Dimensions
LOA (Length Overall) 31.00 ft / 9.45 m
LWL (Waterline Length) 25.60 ft / 7.80 m
Beam 9.84 ft / 3.00 m
Max Draft 5.25 ft / 1.60 m
Displacement 9,479.00 lb / 4,300 kg
Ballast 2,204.00 lb / 1,000 kg
Sail Area (Reported) 512.00 ft² / 47.57 m²
Design & Construction
Hull Type Fin w/spade rudder
Rigging Type Fractional Sloop
Construction FG
Designer Håkan Södergren
Builder Finngulf
First Built 1983
Related Sailboats ["Mp 31" · "Hughes 31" · "Bristol 311" · "Parker 31" · "Cr 310"]
Owner Reviews

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Performance Ratios
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
18.35
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
25.6
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
1.86
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. 6.78
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
2.28
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. 900.08
Rig Dimensions
I (Foretriangle Height) 38.68
J (Foretriangle Base) 11.75
P (Mainsail Luff) 41.01
E (Mainsail Foot) 13.91
SA Fore 227.25
SA Main 285.22
How It Compares

vs. Bristol 311, Hughes 31, Parker 31

This boat Similar boats
Dimensions
LOA
Inferno 31 ★
31.0 ft
Bristol 311
31.0 ft
Hughes 31
31.0 ft
Parker 31
31.0 ft
LWL
Inferno 31 ★
25.6 ft
Bristol 311
24.8 ft
Hughes 31
24.0 ft
Parker 31
28.3 ft
Beam
Inferno 31 ★
9.8 ft
Bristol 311
10.2 ft
Hughes 31
9.7 ft
Parker 31
10.0 ft
Displacement
Inferno 31 ★
9 lbs
Bristol 311
11 lbs
Hughes 31
9 lbs
Parker 31
7 lbs
Ballast
Inferno 31 ★
2 lbs
Bristol 311
4 lbs
Hughes 31
3 lbs
Parker 31
2 lbs
Sail Area
Inferno 31 ★
512 sq ft
Bristol 311
455 sq ft
Hughes 31
Parker 31
448 sq ft
Performance
SA / Displacement (higher = more powerful)
Inferno 31 ★
18.4
Bristol 311
14.6
Hughes 31
Parker 31
19.7
Ballast / Disp (higher = stiffer)
Inferno 31 ★
Bristol 311
40.2 %
Hughes 31
36.8 %
Parker 31
Comfort Ratio (higher = more comfortable offshore)
Inferno 31 ★
25.6
Bristol 311
29.6
Hughes 31
Parker 31
17.3
Capsize Screening (lower = safer)
Inferno 31 ★
1.86
Bristol 311
1.82
Hughes 31
Parker 31
2.09
Displacement / Length (lower = lighter)
Inferno 31 ★
Bristol 311
329
Hughes 31
293
Parker 31
Hull Speed
Inferno 31 ★
6.8 kts
Bristol 311
6.7 kts
Hughes 31
Parker 31
7.1 kts
Speed Number (higher = faster)
Inferno 31 ★
2.3
Bristol 311
1.4
Hughes 31
Parker 31
3.9
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