When working on ice, safety precedes electronics. Check the thickness and condition of the ice in a reliable way, do not step on an unfamiliar stretch just because of interesting depth and carry appropriate rescue means. The ability to measure through ice does not replace proper preparation. A cold-resistant display helps readability, but the spare battery must be kept dry and protected from severe cold.
From a boat, secure the appliance and do not leave it loosely on board. A floating and isolated body reduces the risk of dropping, but does not negate the need for control. Measure at low speed or stationary boat to compare values under similar conditions. After contact with water, dry the housing and check the battery compartment before returning.
The range and stated accuracy should be read as characteristics of the particular device. Don't carry them to other appliances of the same name. Before take-off, turn on the deep meter, check the display and carry a working AAA battery. After the season, remove the battery in prolonged storage if the instruction allows it. Thus, measurement remains a repeatable tool of orientation, not a random digit without context.
For orderly winter preparation see the Submarine Fishing Accessories, The Underwater Rods, winter clothing and equipment and Boats. Measurement only makes sense as part of a safe and complete outing.
