It was found that the bulbous bow carried the water surge along WITH the ship rather than just pushing it to the sides. That's why Dolphins can travel alongside a ship because the ship is providing them with the bow wave that they can travel in. Sort of like guys hanging onto the sides of a San Francisco cable car.
I'm sure that somewhere are publications of the studies done, records of the experiments & calculations of how much speed a ship can increase depending upon the size and shape of the bulbous bow and the size of the ship that it's attached to. Where they are I do not know nor do I really care to find out. I'll let you young whipper snappers do that kind of work.