Speed is related to fuel consumption by a square factor. Doubling the speed increases fuel consumption by a factor of 4. If you have range at a given speed, you can get a good estimate of the range at other speeds by applying the equation: r2 times the square root of v1/v2 equals r1. This will work nicely for operation with Diesel engines. This formula is not 100% accurate because the drag coefficient varies with speed.

Battery performance is a more complex issue because the total power available in the battery is a function of the discharge rate. U-boat batteries only gave roughly 35% of their rated power (100 hr discharge) if discharged over 1 hour. The curve is not linear and the efficiency drops off rather rapidly if the discharge is less than 10 hrs. It gets even more complicated because a rapidly discharged battery will \"bounce back\" after a while and produce quite a bit of power at a low discharge rate. Another complicating factor is that the submerged U-boat uses electricity for other purposes than propulsion, so there is a base line load which must be considered. In fact, at low speed, the base line load can be higher than the propulsion load.

Having said all this, I too would be interested in seeing the actual battery performance curves myself. I am working with approximate data.

Regards,
SuperKraut