then the game needs to be more historically acurate to how the real U.S. submarines made there trips across the pacific,hopefully a 1.3 patch can fix this or it can be somehow modded correctly.which in time i know the devs are doing awesome work, kudos to you guys.:up:

At the root, it's probably the same basic cause as that used to enable the "real life" battery times in that mod. In the game, each boat had a default speed set in the file (.sim file I think, but don't recall right now). All energy usage calculation was based on that speed. If you increased the speed beyond that point, it increased the energy usage by the square of the speed increase factor. Double the speed equalled four times the energy usage, and the default submerged speed was 2 knots. CCIP set it for 4 knots, and the result is that sumberged endurance at 4 knots is pretty much what it was supposedly in WWII. The submerged endurance at higher speeds is closer to true than it was with the default settings, but endurance at slower than 4 knots is a good bit higher than real life was.

Probably the game has a default speed setting for surface movement, likely 10 knots from what has been said, and moving faster or slower than that speed changes fuel consumption. Since going slower means you don't move quite as far in the same time while you might use less fuel per hour you don't get quite the same fuel economy that way.