2 knots, why are you going that slow? You can set your speed to 10 knots and happily travel all over, use flank only when chasing a target and when submerged I go for ahead 2/3rds when spending a day underwater (avoiding air cover) or in rough seas etc your batteries will last a good 12 hours or so. Also refuel at midway like previously said to top your fuel before the long haul to your target (I do travel at flank speed to miday only when at the beginning of a mission).
|