A special type of bow, called a bulbous bow, is often used on large power vessels to reduce wave-making drag.  The bulb alters the waves generated by the hull, by changing the pressure distribution ahead of the bow. Because of the nature of its destructive interference with the bow wave, there is a limited range of vessel speeds over which it is effective. A bulbous bow must be properly designed to mitigate the wave-making resistance of a particular hull over a particular range of speeds. A bulb that works for one vessels hull shape and one range of speeds could be detrimental to a different hull shape or a different speed range. Proper design and knowledge of a ships intended operating speeds and conditions is therefore necessary when designing a bulbous bow.