Fuel needed

[Barkerov]

Originally Posted by flyer102

Theoretically, going at the slowest speed possible is the most fuel efficient. For instance going ahead 1 knot will be THE most fuel efficient, however if you value your time and sanity, don't go 1 knot when your traveling over 2-3k miles.

What you said before this is true but this statement is not, or at least it shouldn't be. All engines, regardless of type, have an optimal speed at which range is maximized. You can find this in SH4 for each sub by setting the knotometer yourself using medium TC for a couple of seconds so that your speed stabilizes and then ask the navigator what your maximum range at current speed is.

I have found for fleet boats this is about 10.5 knots and for the S-class 7.5 knots