The standard that establishes the design categories and their characteristics is the European Directive 2013/53/EU. It is assumed that the further a boat is from the coast, the worse weather conditions it may be subjected to, and worse, for longer periods of time. Based on this premise, reserve buoyancy, stability and structural strength will differ, depending on the intended use of the manufacturer’s design. Thus, when a manufacturer builds a boat, he assigns it a design category, which will determine the maximum sailing area in which the boat will be able to sail.
Characteristics of the design categories
Category A. Oceanic: Fuel tanks with large capacity to achieve greater autonomy and structural resistance to withstand weather conditions with winds above force 8 on the Beaufort Scale and waves of more than 4 metres in height.
Category B. High Seas: Structural strength to withstand weather conditions of force 8 on the Beaufort scale, about 40 knots, and wave heights up to 4 metres.
Category C. Coastal waters: Structural strength to withstand weather conditions of Beaufort force 6 (25 knots) and waves of 2 metres.
Category D. Inland and sheltered waters: Structural strength to withstand 30 centimetre waves and winds of force 4, equivalent to 15 knots.
The design category is usually stated on the builder’s plate together with other relevant data such as maximum load and maximum number of persons.