I disagree Hinrich. When I am at 10 knots I get the perfect balance of charging to mileage. I have taken measurements of how many miles I have left at 10 knots then submerged for an entire day and resurfaced and charged and I always have more miles to fuel ratio than I did before I submerged.
Since I am subtracting miles from my destination while underwater running on batteries it works out in my favor every time when I switch to running submerged during the day at one third and surface at night and run one third.
