But the hull speed is a theoretical maximum based on hull length. Back in the real world; for a given hull, the more she displaces, the slower she is going to be. So, what little hull length gained by your fresh water allowance is mostly consumed by your greater friction losses from a greater surface area. And since the difference in potential speed is negligible to begin with, vis-a-vis fresh/salt, we've probably rung about all we can out of this topic.(g)
but I could be wrong. (g)
“Scientists are people who build the Brooklyn Bridge and then buy it.”
Wm. F. Buckley, Jr.