automatic release instrument with underwater buoy for marking of field equipment

In practical fieldwork one often encounters the problem of marking registration instruments placed below the water surface. Marking buoys can for various reasons disappear if they are placed visibly, valuable equipment and data thus being lost. In this paper a new technique and a new instrument for marking field equipment are introduced. The instrument, which in principle consists of an anchor, a buoy, an electronic circuit with a clock, and a release mechanism, is to be placed on the bottom. After a predetermined time span the clock triggers the release mechanism, and the buoy and the instrument float to the surface, where they can be collected with good accuracy in time.