But Art since this is about FD I will add .......
The FD hull is shaped to fit nicely on the face of the following wave .. the one right under the stern. It not only fits nice but this fit allows the water under the boat to flow smoothly and gracefully boak to it's original state before the boat came along pushing it down and to the side.
Look back in historical pictures and before engines you will not see ANY other than FD hulls. There was not enough power in sails to exceed hull speed so there was no point in building and designing boats to attain much less exceed hull speed. So boats were designed to make the best of the way water moves around and under boats.
The FD hull not only allows the water to flow smoothly around a hull but at speeds a bit under hull speed the following wave is slightly ahead of the stern of the boat. And since the stern is shaped much like the wave it can, to some degree surf down the face of the wave thereby actually pushing the bow into the sea ahead. Kind of like a turbocharger helping to push the intake air into the engine the energy of the following wave helps push the boat forward. That energy of course is made by the bow pushing water down and aside. And Art that energy is almost totally lost on the typical SD or planing hull. There is probably some but it must over come the huge drag of the submerged transom. Look over the stern of your boat at 7 knots. You will see a wide area of water that is jumping up and down frothing in a mass of energy released by the transom stern and created by the bow/propeller/engine. Mostly lost.
So the turbulence of the large submerged transom of the SD or planing hull is not the only reason FD boats are far ahead of others in slow speed efficiency. The FD hull not only has very low drag it reclaims some of the energy lost pushing the sea down and aside.
Due to their length many ships are designed to take advantage of the second following wave made by the ships bow. Some like a great lakes ore ship may take advantage of the 4th or 5th wave back. They do this of course by adjusting their speed so the wave under the stern is slightly ahead .. of the stern. And we w trawlers do the same by adjusting our speed to adjust the position of the following wave to a tad ahead of the stern ..... one knot below hull speed typically.