Better than the kitchen egg timer your XO picked up at the Exchange, Safety Sweep Timer (when used on the iPhone) also provides tactile feedback to let you know its time to take another peek at a particular view that may be blocked or be of interest. It doesnt just keep track of the safety-of-ship/look interval, it allows you to set a secondary timer to account for the time it takes to get yourself ready before you violate your timer interval.
No need to take your gaze away from your panel, turn on another blinding light, or otherwise distract your attention for this routine, yet crucial, task.
Simply dial in the desired interval, drop it in your pocket, and give it a shake to start or reset the countdown. When you feel the buzz or hear the beep, youve got 10 seconds before you violate your safety sweep interval (this time can be adjusted in the settings).
For further submarine/ship/navy training stuff, check out "MoBoard" and "Ekelund Range" also from SlimeSoft.