Bulbous Bow
As has been stated, they have to be designed and applied correctly. There are many boats performing fine with and without them. Here is a picture of ours and Ed Monk's design philosophy in applying it to our boat.
"Hull is bulbed, which effectively increases waterline length for slightly better efficiency and speed. Bulb also damps pitching, but is elliptical in section to minimize splash when entering or leaving the water. The hull was disigned with the bulb not added after the fact"
Having spent a lot of hours on similar displacement hulls without one, I can say the bulb is a positive addition to our hull's design.