Engineering:F-31 Sport Cruiser

Short description: Sailboat class

F-31 Sport Cruiser

F-31 with mainsail reefed
Development
Designer	Ian Farrier
Location	United States
Year	1991
Builder(s)	Corsair Marine
Boat
Boat weight	3,630 lb (1,647 kg)
Draft	5.50 ft (1.68 m) with daggerboard down
Hull
Type	Trimaran
Construction	Fiberglass
LOA	30.83 ft (9.40 m)
LWL	30.00 ft (9.14 m)
Beam	22.42 ft (6.83 m)
Engine type	Outboard motor
Hull appendages
Keel/board type	daggerboard
Rudder(s)	internally-mounted spade-type rudder
Rig
Rig type	Bermuda rig
Sails
Sailplan	Fractional rigged sloop
Total sail area	599 sq ft (55.6 m2)
Corsair Cruze 970 →

The F-31 Sport Cruiser is a family of United States trailerable trimaran sailboats that was designed by New Zealander Ian Farrier and first built in 1991.

The F-31 is the production development of the Farrier F-9, which were built by custom shops in small numbers and by amateur builders from plans. The first F-9 prototype was launched on 29 September 1991.

Production

The boats were built by Corsair Marine in the United States , starting in 1991, but are now out of production.

Design

F-31

F-31

Corsair F31 with its outriggers folded

The F-31 is a small recreational trimaran, built predominantly of fiberglass. The hull is constructed with a rigid PVC foam core, vacuum bagged moulded to the skins, while the structural beams are reinforced with carbon fiber.

It has a fractional sloop rig, a plumb stem, a reverse transom, an internally-mounted spade-type rudder controlled by a tiller and a retractable daggerboard, mounted at 18°, with the daggerboard trunk stepping the mast. The outrigger floats are folding for storage or ground transportation on a trailer, with a maximum width of under eight feet for highway transport. The outrigger floats fold into cutouts in the lower hull to reduce trailering width. When deployed the outriggers are set at a fixed 8° to the hull, so that they are upright and thus symmetrical, when each is in the water. Due to the employment of a daggerboard, the design can easily be beached.

The boat is normally fitted with a small outboard motor of typically 9.9 to 15 hp (7 to 11 kW) for docking and maneuvering.

Operational history

In 1992 the F-31 was named the Australian Sailboat of the Year. In April 1992 Fred Gan's F-31 Ostac Triumph won the bi-annual Australian Offshore Multihull Championships. In the associated Brisbane to Gladstone Ocean Race, Bobsled, a 67-foot, million dollar, racing monohull boat, sponsored by Société Générale, made headlines in breaking the monohull record by an impressive hour and a half. The trailerable F-31 caught and passed Bobsled, finishing an hour and fifteen minutes ahead.

In a 2000 review, writer Bob Perry of Sailing Magazine wrote of the F-31, "In looking at the accommodations, it would be better not to compare this design to a monohull with a similar LOA but, instead, to compare displacements. There is no question that the 31-foot Farrier tri has less interior volume than a standard 31-foot monohull, but you cannot trail[er] most 31-foot monohulls. The F-31 has comfortable accommodations for two couples, and boat speed that will blow the doors off a 31-foot monohull...Ian designs handsome boats. The F-31 is no exception... Just be aware that this 31-footer is capable of sailing with some big monohulls."

Variants

F-9A

The initial F-9, designed for amateur construction from plans. More than 300 completed.

F-9AX

A version of the F-9A with expanded interior space, with a 15% wider center hull for more room and a 16% higher load capacity. Trailering beam was also increased to 2.9 m (9.5 ft).

F-9R

A high performance racing version of the F-9A with a rotating mast.

F-31 Sport Cruiser

This model was designed by Ian Farrier and built by Corsair Marine. It improved over the F-9 in having a smaller folded width for trailering of under 8 ft (2.4 m). It has a length overall of 30.83 ft (9.4 m), a waterline length of 30.00 ft (9.1 m) and displaces 3,630 lb (1,647 kg). The boat has a draft of 5.50 ft (1.68 m) with the daggerboards down and 1.67 ft (0.51 m) with the daggerboards up. The fresh water tank has a capacity of 20 U.S. gallons (76 L; 17 imp gal). The boat has a hull speed of 7.34 kn (13.59 km/h).

Corsair 31

This model was designed by Ian Farrier and built by Corsair Marine. After Corsair and Ian Farrier ended their business relationship in 2000, Corsair continued to develop the F-31's design and renamed the modified design the Corsair 31. It has a length overall of 30.83 ft (9.4 m), a waterline length of 30.00 ft (9.1 m) and displaces 4,600 lb (2,087 kg). The boat has a draft of 5.50 ft (1.68 m) with the daggerboards down and 1.33 ft (0.41 m) with the daggerboards up. Options included a racing package, with a bowsprit and carbon fiber spars. It was built in an aft-cockpit and center-cockpit version. It has a hull speed of 7.34 kn (13.59 km/h).

See also

• List of sailing boat types
• List of multihulls

Related development

• F-27 Sport Cruiser