What is purpose of Bulbous Bow fitted on ships?

Bulbous Bows are fitted on ships because they can:

• give an increase in speed for similar input of Engine power. This may be up to 1/2kt when fully-loaded and up to C3/4 kt in ballast condition.
• give extra strength at bottom of Fore Peak tank.
• reduce vibration amplitudes in the Fore Peak tank.

However, Bulbous Bows are expensive to install. On small, slow service speed vessels they can actually cause increased resistance to forward motion.

Note:-

Vessels operating at higher speeds, and those with high block coefficients, are often found to have a bulbous or protruding bow below the waterline.

It may be indicated that like most peculiarities of the immersed hull form this feature is usually intended to reduce the vessel’s resistance to motion under certain conditions.

The bulbous bow has several important advantages and does not present relevant disadvantages: