prop2max_dw = dict(length=lambda x: (x / 3.45) ** (2.5),
                       beam=lambda x: ((x / 1.78) ** (1 / 0.27)),
                       draught=lambda x: ((x / 0.8) ** (1 / 0.24)),
                       service_speed=lambda x: ((x / 1.14) ** (1 / 0.21)),