Ahead Flank should be the 20 knots, Ahead Full might be 17, but Ahead Standard should be around 10-12 knots, and should be close to the most efficient setting. When you start out of Pearl or where ever, run the whole way at 9 or 10 knots, which ever gets you the best mileage, even if you have to use the knot gauge to set the speed. The only time you do Ahead Full or Flank is when you have to in order to catch a potential target, or get out of the way of a bomb drop...
