It starts at the bottom of the boat with a 110 pound keel that separates you from the rocks.....12 by 12 by 1 1/4 inch steel I beam. Notice the skegs under our propellers, 2 1/2 solid steel that protects the props and supports the rudders. On most boats the props are totally exposed and logs can wipe them out not to mention bumping into a rock! We turn 58 inch props as slow as possible.....that's the equation for less fuel burned. We typically use 15 gallons per hour running two engines and a generator....not bad for a 175 ton Expedition Yacht.