For anyone that didn't read the article: Without the bulb, the prow slices through the water and causes the water to ride up the sides of the ship.
The bulb on the bow is under the waterline. This forces water up in front of the ship before the prow. The bulb is designed so that the bulb-rise of water cancels the prow-rise of water in destructive interference.
The bulb design only works at certain speeds, water conditions, etc.
