UBOAT Calculator

Ship Distance Calculator

Measure distance using mast height through the periscope

Use the tick markers on the side of the 1/32° periscope to measure the height of the masts from sea level to the top mast.

Please enter both values.

Distance by Ship Length Calculator

Measure distance using ship length and AOB through the periscope

Use the tick markers on the bottom of the 1/32° periscope to measure the angular length of the ship.

Please enter all values.

AOB & Speed at Observed Angle Calculator

Determine angle on bow and speed from periscope observations

Use the tick markers on the bottom of the 1/32° periscope to measure the observed length of the ship.

You can also time how long the ship takes to traverse its own length past a fixed reticle mark to determine its speed.

Please enter required values to determine AOB.

Please enter all values to determine speed.

Mirror ↔ Flip ↕

Intercept Course Calculator

Calculate the heading to intercept a moving contact

Contact course is absolute, not relative bearing. Eg North = 0, South = 180. Bearing to Uboat is relative.
To arrive early, insert a slower Uboat speed than you intend to travel but use the same intercept angle.
Draw intercept line starting from target, then to Uboat, then to calculated angle. Adjust for direction of travel on inside angle.

Please enter all values.

Attack Disk Calculator

Resolve own course, bearing, target course, and AOB relationships

Resolves own course, bearing, target course, and AOB geometry. Enter own course and bearing, then choose whether to enter target course or AOB to derive the other.

Please enter own course and bearing.

Speed from Bearing & Distance Calculator

Determine target speed from two bearings and distances over time

Enter 2 visual bearings of your target, the distance of the target at each bearing, and the elapsed time between bearings to estimate the target ship speed.
You can do it whilst remaining stationary, or you can do it while moving, but you must maintain a constant course to make the calculations work.

• If you are moving, not only will you need to maintain a constant course, you will need to know how far you have moved between bearing readings. You can use the map to measure it (mark your position when taking bearings), or you can use the Distance Travelled at Speed Calculator above.

Please enter values for bearings, distances and time.

Ekelund Range Calculator

Estimate range from bearing rate and speed data (Ekelund method)

Estimates range from two bearing observations, own and target course/speed data. Enter the start and end bearings to the target and the observation time — the bearing rate is computed automatically. Tick the lag box if both ships' cross-LOS velocities move the bearing in the same direction (e.g. both moving right across the line of sight).

Please enter all values.

Double-Leg Ekelund

Estimate range from two observation legs at different courses

Range from two observation legs at different courses. Enter start/end bearings and observation time for each leg — bearing rates are computed automatically. No target speed needed.

Please enter all values for both legs.

Multiple Target Synchronised Detonation Calculator

Calculate firing times for synchronised torpedo impacts on multiple targets

• All values must be accurate at the moment you fire the first torpedo. Do not change them after you begin firing.
• Remain stationary until all torpedoes have been fired.
• Sharp angles may cause small inaccuracies — torpedo gyro angles and bow/stern firing arcs are not modelled.
• If a target cannot share the same detonation time as the others, it will be excluded from the results. Try changing its torpedo speed, or reposition and re-measure.
• Depending on your difficulty settings, you may need to manually update distance and AOB before firing torpedoes 2–5. The expected values at firing time are included in the results.
• If measuring distances from the map, there is ~99m margin of error beyond 1km due to the game rounding to one decimal place. For better precision, use the Ship Distance Calculator on this page or the stadimeter in the game, or measure with two map circles:
  • Draw a circle from your sub to within 1km of the target.
  • Draw a second circle from the target to touch the first.
  • Add both radii for an accurate distance.

Pro tip: Pause the game and measure all targets right before firing the first torpedo.

Please first enter all values for each target that requires a solution.