Originally Posted by
gcarter
Bill, back in the early '70's when I was working for a Naval Architect in Houston, so little was understood about them, only that they seemed to make the water react like the ship was 10-15% longer than it was........at displacement speeds, the longer ship can be more easily driven than a shorter ship. So if you had a 400' ship, but it performed like it was 500' long, it was cheaper to operate. Take those savings, multiply them by 12 months a year, and over a life of 20 years, you can see the motivations for them.
Back to the '70's, bulbs were round, not very long, and hemispherical on the front. The height was from the keel upward to just below the light water line, or so.
Today, bulb design has seemingly taken on a life of its own. They seem to be much longer than they were when I was involved. Also many seem to have flat upper surfaces and are placed just below the water line. If you get an opportunity to see some newer versions (newer cruise ship models are always on the cruise ship somewhere) it's obvious a lot of time and effort is invested in the shape of them.
I suspect more can be gained from good bulb design than almost anything else that can be done.