Ochette.The first white crests which form on the sea surface with a wind over 15 knots.
OffshoreOffshore navigation
OilskinWaterproof jacket, once made of waterproof canvas
One designSeries of boats with the same size and design which can compete with no compensated times.
One-off.Racing boat prototype
Onshore windSide exposed to bad weather: wind and waves in a harbour or a roadstead
Optimist.Boat with centreboard, chine hull and flat bottom designed by Clark Mills in 1954 ;she measures 2.30x1.13 m
ORC.Offshore Racing Council: l' international organisation which is in charge of IOR classes and offshore regattas.
Orthodromic courseCourse along the maximum circle and the shortest one between two points. See also‚ Lloxodromic
Oscar.Term which represents ‚O‚ in the international phonetic alphabet.
OsmosisThe result of a catalyzation flaw of sealants in fiberglass hulls. Water enters through the gelcoat, it increases the inner volume and creates some bubbles which can delaminate the hull
OutboardEverything out of the boat. Usually referring to an external engine
Outboard motorA removable engine mounted on the stern of the boat, or in a motor well.
OverallMaximum lenght of the boat
OversetA heeling able to submerge the toerail