This app is designed to check the accuracy of a submarine officer's Ekelund range estimate of a target based on bearing rate, using the standard formula developed at the US Navy Submarine School.

The Ekelund range is useful for estimating range to a contact with only its SONAR bearings. The app takes your vessel's speed, course, bearing to the target, and the target's change in bearing rate over two maneuvering legs.

Instructions:
Set the target's movement components (true bearing and two bearing rates). Set your ship's components (course & speed) for the two legs. The range will be estimated based on the standard Ekelund ranging method.

Select the value to change by tapping it. The value selected will become highlighted. Change the value by sliding the scale at the bottom of the screen left or right. The range will automatically update with the slider once all of the values have been updated.

If you already know your ship's speeds across the line of sight, use "000" for Bearing, then 090 and 270 for legs 1 & 2 courses respectively.