The resistance acting on ships advancing in waves increases comparing with those in calm water, which will undoubtedly effect the ability of ships to keep speed in seaway.Added resistance represents the margin of the former over the latter, which is induced by winds or waves. It is also the key to the calculation of ocean factor fw in EEDI formula presented by IMO. So added wave resistance is one of the important factors which should be taken
into account in ship's design stage.