(Figure 201, An Album of Fluid Motion,p117) Wave pattern of a ship

An aerial photgraph from directly overhead shows, away from the breaking wave from the bow and its turbulent wake , the asymptotic pattern deduced by Kelvin in 1887. The waves are confined to an angle of 19.5 degrees on either side of the path of the ship, in agreement with the theory, with an effective origin that is displaced approximately one ship length ahead of the bow, Newman 1970