This app rings or vibrates on the hour and half hour in a standard ship's bells pattern.
You can set "quiet hours" during which the app will neither ring nor vibrate.
kw: ships bells, navy
* Fixed the bug that made it ring on the half hour even when "hour only" was checked.
A bug has been reported for devices running KitKat that sometimes the bells ring at the wrong time. I am aware of this issue and will address it in the next version, which will be a complete rewrite, including an updated interface.