The F-31 is a small recreational trimaran, built predominantly of fiberglass. The hull is constructed with a rigid PVCfoam core, vacuum bagged to the skins, while the structural beams are reinforced with carbon fiber. It has a fractionalsloop 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 for docking and maneuvering.
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, writerBob 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 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 ;F-9AX ;F-9R ;F-31 Sport Cruiser ;Corsair 31