The clocks and associated devices described herein operate on one of the following principles; electrical, mechanical, electrolytic, or electro-mechanical combination. These devices are used separately or in combination in ground influence, moored influence, moored contact, or drifting contact mines. The following mechanisms are described: Arm-ing clocks, disarming clocks, sterilizers, on-off arming-disarming clocks, scuttling clocks, and period delay mechansims.