Nothing fancy. Courtesy of copious amounts of miller light with a shot or two captain Morgan. Got a little captain in ya?

And yes, that ahead standard is 15 knots. Come to find out, the only reason why 10 knots is the most fuel effiecient is because that's what was commonly accepted since SH3, but it's not true. It's what you set it at, based on surface endurance. If you say 15000 NM @ 10 knots, then 10 knots is your most fuel effieient. If you say 150,000 NM at 15 knots.. then 15 knots becomes your new sweet spot. Granted you could get more range by going at 10 knots, but since fleet boats cruised faster then 10 knots, and the pacific is the worlds largest ocean, 10 knots sucks balls, quite frankly.