It has long been recognized that one of the principle factors which determines the amount of power which is required to propel a hull at a given speed is the effect of skin resistance or skin friction. This effect results from adhesive forces between the hull surface and the water which causes a belt of eddying water to be maintained close to the surface of the hull. The energy required to overcome the skin friction of the hull increases the fuel consumption and decreases the overall efficiency of the vessel. With the advent of ever rising fuel costs and in view of the desire for increased travel speeds, the effects of skin friction assume important proportions.
In the past various expedients have been resorted to in an attempt to reduce the effects of skin friction. Included among these are attempts to reduce skin friction by making the surface of the hull extremely smooth in an effort to reduce the adhesive forces between the water and the hull. This technique has several practical disadvantages among which are increased initial manufacturing costs and increased operating costs resulting from a need to periodically clean the hull to remove fouling matter. In addition, there are inherent limitations on the degree of smoothness which can be achieved on a hull of relatively large size before the associated manufacturing costs become prohibitive.