Scan depth
the
maximum depth at which the sonar locator (see "Type") is able to operate effectively — in other words, how deep underwater the device is able to "see".
It is worth choosing an echo sounder according to this parameter, taking into account the actual depths at which it is planned to be used. Of course, this does not place a certain margin, but within reasonable limits (15-20%, less). For example, it hardly makes sense to specially take a model with a scanning depth of 200 m for a lake with pits of 30-40 m — such devices are expensive, while there will simply be nowhere to realize their full potential, and a powerful signal can also scare away the fish. But for marine or oceanic applications, a depth of a kilometer or more may be required; the most advanced echo sounders are quite capable of providing it.
Wireless sensor
The presence
of a wireless sensor in the scope of delivery of the echo sounder.
The main features and conveniences of such sensors are obvious from the name: to install them, you do not need to bother with laying and fixing wires, it is enough to fix the module in the required place and turn on the connection. On the other hand, wireless sensors are noticeably more expensive than wired ones, and their operation requires their own power supplies; the state of these sources (accumulators or batteries) must be monitored separately so that the sensor does not turn off at the most inopportune moment.
Note that there is a specific type of device with a similar function: echo sounders that do not have displays at all and are connected to a mobile device (smartphone or tablet) during operation. In terms of functionality, such models are often not inferior to full-fledged echo sounders, while being much cheaper.
Ice fishing sensor
The presence
of a sensor for winter fishing in the scope of delivery of the device with the function of an echo sounder (see "Type").
This feature allows the device to be used on ice-covered water bodies. Usually, the sensor itself is made in the form of a float and is designed to be placed directly in the hole. At the same time, some models are also able to “see” directly through the ice to some extent, but this function is usually auxiliary and is intended more for a general assessment of the depth, and not for a detailed display of the situation; and the working depth during such work is less than the regular one. There are two things that are common to all winter sensors: the absence of mounts found in conventional sensors (on the bottom of the boat, transom, etc.), as well as increased resistance to low temperatures.
