Periscope Watchkeeper is the only publicly available submarine periscope operator training application. Submariners from many navies have used this application to either learn the core mental maths or sharpen their skills in preparation for workups, courses or missions.

This training game provides the essential skills for determining another vessel's aspect (ATB), calculating the Duration of Attack and Distance Off Track, conducting passive ranging and calculaing the look interval.

Features:
- Five ship types (Arleigh Burke, Zumwalt, QM2, Daring class and a cargo ship)
- Four difficulty levels for ATB game mode
- Up to three targets for passive ranging and look interval mode
- Night mode
- Distance Of Track calculations
- Duration Of Attack calculations

Additional features will be made available free of charge in form of updates.

Currently used by submariners from:
Australia
Canada
United States
France
United Kingdom
Japan
Thailand
South Africa