2.4 What is design category?

Design category is an important element of safe boating! It defines the weather and nautical conditions in which it is safe to operate your boat.

Not respecting the design category limitations of your boat can put you and your passengers at risk.

Do not exceed the maximum permitted engine power or number of persons on board.

Ensure that the anticipated wind and sea conditions correspond to the design category of your boat.

Always make sure your boat and your operating skills match the weather and water conditions where you are going to operate.

Design category conditions are specified using maximum wind speed and maximum significant wave height as measurement. A significant wave height refers to the average height of the highest one third of all waves, visually estimated.

For example, design category C conditions are typically encountered in exposed inland waters, estuaries and coastal areas in moderate weather conditions. Design category B conditions are more severe — typically encountered offshore, but also in coastal areas and larger inland waters where sheltered areas are not readily available.

Table 1. Design category specification
Description Category A Category B Category C Category D
Wind force Beaufort force exceeding 8 Beaufort force 8 or less Beaufort force 6 or less Beaufort force 4 or less
Significant wave height >4 m >13 ft ≤4 m ≤13 ft ≤2 m ≤6.6 ft ≤0.3 m ≤1 ft
What is my boat’s design category?

Your boat’s design category is indicated on the builder’s plate. You can also check it from the Technical specification in this manual.

Be aware that your boat can be used in different conditions depending on the number of people on board. So please make sure you follow the safety rules, for example:
  • For category C conditions, you can have the maximum number of passengers indicated on the builder’s plate on board.

  • If you venture out to waters with design category C conditions, you must restrict the number of passengers to the lower limit on the builder’s plate.