The design categories (A-D) define the wind force and significant wave height in which the craft is designed to operate in. Your boat's design category, that is stated on the builder's plate, is B.
In category B
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The wind force is no more than 8 on the Beaufort scale (approx. 21 m/s).
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The significant wave height is no more than 4 m.
The significant wave height is the average height of the highest one third of all waves, visually estimated by an experienced observer. Some waves may be twice as high as the significant wave height. These conditions can occur in open water on lakes, estuaries, and in coastal waters in moderate weather.