White-Water Wake Characteristics of Surface Vessels

The visible white-water generated by a vessel is a streak of foamy, aerated turbulent water. Aerial photographs showing the white-water wakes generated by vessels underway were examined to study wake characteristics of these surface vessels. Both visual and dimensional analyses of the photographic data were performed. The major variables that influence the production, geometry, persistence and visibility of the foamy white-water the wake generated by surface vessels were identified and discussed. In a majority of the nondimensional plots involving these variables, the data appeared to collapse onto curves unique to each vessel class, with the propeller tip to surface clearance of each vessel class determining the relative location of these curves on the plots. Vessels with minimal tip to surface clearance had longer, stronger and wider white-water wakes than those with significantly deeper propellers. The white-water wake length data appeared to collapse, within an order of magnitude, onto four different curves. The best of these curves revealed that the maximum length of the visible white-water wake was proportional to a ratio of the vessels speed raised to a power divided by the vessel propeller revolutions per second raised to a different power. The data scattered no more than a factor of three below the curve. The width of the turbulent boundary layer and bow wave portions of the overall wake and the length of the initial spreading region and far wake region of the propeller wake all increase as the speed of the vessel increases. The wake geometry and characteristics of a single class of vessels may exhibit some type of similarity.