The original photo's of those megayachts look butt ugly in my opinion. And I really can not see the point. Sailing vessels have a very different reason for a bow like that. A powered vessel, of which this Forum is about" requires a very different approach to taking on large sea's and I can only say that to have a bow like that, you'd have to be nuts.
Bow Bulbs on ships is a very different reason compleatly. The bulbs are often full of fuel
, so don't always offer xtra flotation, however, extra bouyancy on the bow is sometimes done this way. I know of several boats here that had this type of design done with the main priority to give the bow a lot of bouyancy. Personly, I feel it was because the original design never worked properly and the bulb was an "idea" to solve an issue in the design.
On large ships, that bulb is to change the bow wave and reduces large amounts of wave height moving out from the vessel. The size of the wake is a direct proportion to the amount of energy the ship requires to move through the water. So reducing the wake means less power required to push it along. Not greatly measurable in smaller vessels, but in large megaton vessels, small percentages of efficiency gains equates to large savings in fuel
. Some of those huge container vessels can be burning fuel at a rate of upto 10tonnes/hr. The bulb also lengthens the water line which results in extra speed or reduced effort once again. It's quite amasing to find such small wakes behind many of the newer modern ships of today. Environmental impacts are trying to be reduced as much as possible.