Today we made the yacht watch timer pictured below. It was ordered by a solo sailor to use to ensure that she does not fall asleep for too long while on watch (checking the horizon for potential dangers).

As this is such a vital piece of equipment, we actually put two independent timers onto the same circuit board doubling up on all components including the warning buzzers. Therefore if a component on one of the timers fails, the second timer will continue to work perfectly.

The user can set the number of minutes the timers are to run before the warning piezo buzzers sound – e.g. 5, 10, 15, 20..etc minutes. Timer-2 is then automatically set to run for one minute longer than Timer-1.

While the device is connected to the 12VDC system on board, a pair of panel mounted LEDs flash once every second to show that the timer is running. Each time the sailor checks the horizon they press a panel mounted button to restart the timer countdown.

If the sailor falls asleep or forgets to keep watch then when the timer has run down Timer-1’s buzzer will sound for one minute. (We left the protective sticker over this buzzer to keep the sound level down.) If the sailor still does not press the button during that minute, then Timer-2’s buzzer will start to sound very loud and continue to sound until the button is pressed.

The sailor will fit an ON/OFF switch before the timer device. Each time it is switched on, both LEDs will light up and the two buzzers will sound for one second to confirm that everything is working as it should. The programmed number of minutes for the timer are stored in memory and are not lost when power to the device is disconnected.

The timers are built using Picaxe-08M2 microcontroller chips each powered via its own 5V regulator. The device is fitted with reverse polarity protection.