Inferna: ORC Rating

GPH

681.5

OSN

666.5

LOA

9.447 m

Displacement

4316 kg

Triple-Number Ratings

Lower is faster

Triple Inshore

Low

0.6125

Medium

0.8067

High

0.9076

Triple Offshore

Low

0.7875

Medium

0.9854

High

1.081

Boat Specifications

Dimensions

Length overall: 9.447 m
Beam: 3.02 m
Draft: 1.63 m
Displacement: 4316 kg
Crew weight: 460 kg
Wetted surface: 20.63 m²

Sails

Mainsail: 33.06 m²
Genoa: 30.29 m²
Spinnaker: 61.9 m²
Asymmetric spinnaker: 0 m²

Design

Type: Inferno 31
Builder: Finngulf Marine
Designer: Håkan Södergren
Year built: 1982

Performance data

Polar CSV

Each row is TWS followed by TWA and boat-speed pairs. Paste it directly into Offwind or compatible navigation software.

6,42.4,4.441704,52,4.97,60,5.25,75,5.49,90,5.45,110,5.29,120,5.13,135,4.66,147,4.089806,150,3.96
8,41.6,5.175194,52,5.81,60,6.06,75,6.23,90,6.24,110,6.26,120,6.13,135,5.64,150,4.94,152,4.8474
10,41.6,5.710097,52,6.25,60,6.42,75,6.55,90,6.61,110,6.69,120,6.62,135,6.35,150,5.78,153.5,5.620524
12,40.9,5.887385,52,6.42,60,6.59,75,6.76,90,6.82,110,7,120,6.94,135,6.72,150,6.4,166,5.89511
14,40.5,5.957344,52,6.49,60,6.67,75,6.91,90,7.03,110,7.31,120,7.28,135,7.04,150,6.74,180,6.31
16,40.1,5.961397,52,6.53,60,6.71,75,7.01,90,7.23,110,7.55,120,7.62,135,7.39,150,7.03,180,6.67
20,40.5,5.983646,52,6.54,60,6.73,75,7.09,90,7.51,110,7.83,120,8.12,135,8.09,150,7.71,180,7.27

Wind Speed	52°	60°	75°	90°	110°	120°	135°	150°
6	4.97	5.25	5.49	5.45	5.29	5.13	4.66	3.96
8	5.81	6.06	6.23	6.24	6.26	6.13	5.64	4.94
10	6.25	6.42	6.55	6.61	6.69	6.62	6.35	5.78
12	6.42	6.59	6.76	6.82	7	6.94	6.72	6.4
14	6.49	6.67	6.91	7.03	7.31	7.28	7.04	6.74
16	6.53	6.71	7.01	7.23	7.55	7.62	7.39	7.03
20	6.54	6.73	7.09	7.51	7.83	8.12	8.09	7.71

Wind Speed	Beat Angle	Beat VMG	Run Angle	Run VMG
6	42.4°	3.28	147°	3.43
8	41.6°	3.87	152°	4.28
10	41.6°	4.27	153.5°	5.03
12	40.9°	4.45	166°	5.72
14	40.5°	4.53	180°	6.31
16	40.1°	4.56	180°	6.67
20	40.5°	4.55	180°	7.27

VPP POLAR · BOAT SPEED BY TWAKT

TRUE WIND ANGLE —

READ AT ANGLE

Hover or tap the chart, or use the slider, to read boat speeds.

True wind speed 6 kt8 kt10 kt12 kt14 kt16 kt20 kt

Data table

Boat speed by true wind angle and true wind speed
TWA	Boat speed in 6 kt (kt)	Boat speed in 8 kt (kt)	Boat speed in 10 kt (kt)	Boat speed in 12 kt (kt)	Boat speed in 14 kt (kt)	Boat speed in 16 kt (kt)	Boat speed in 20 kt (kt)
0°	0.00	0.00	0.00	0.00	0.00	0.00	0.00
52°	4.97	5.81	6.25	6.42	6.49	6.53	6.54
60°	5.25	6.06	6.42	6.59	6.67	6.71	6.73
75°	5.49	6.23	6.55	6.76	6.91	7.01	7.09
90°	5.45	6.24	6.61	6.82	7.03	7.23	7.51
110°	5.29	6.26	6.69	7.00	7.31	7.55	7.83
120°	5.13	6.13	6.62	6.94	7.28	7.62	8.12
135°	4.66	5.64	6.35	6.72	7.04	7.39	8.09
150°	3.96	4.94	5.78	6.40	6.74	7.03	7.71