Purpose. This study aims to describe a prototype of a string wave gauge designed for dynamic recording of wave elevations in both salt and fresh water across a wide range of wavelengths, including capillary waves. The prototype is engineered to be insensitive to salt deposition on the conducting wire and resistant to short circuits caused by conductive debris. It is intended for use in unattended wave gauge “grids” to record two-dimensional wave spectra and to support sea wave studies with remote sensing methods for data interpretation and validation.

Methods and Results. A capacitive string wave gauge featuring a shielded wire configured as a closed two-wire loop is presented for measuring water surface elevations in both salt and fresh water. Compared to a conductive wire, the shielded wire prevents sensitivity loss due to salt deposition and eliminates short circuits caused by small conductive debris. The wave gauge exhibits a wide linear dynamic range, capable of recording waves from millimeters to several meters in height in both salt and fresh water. During operation, the wire requires no cleaning, and the gauge can remain submerged for extended periods without loss of sensitivity or temperature-induced signal “drifts”.

Conclusions. The operational principles and design features of the wave gauge are described, along with the results of testing in river and sea conditions. The influence of the distance between the “strings” on the device’s effectiveness in salt and fresh water was investigated under laboratory conditions. For a multi-string design, a method to eliminate mutual interference among the wave gauge “strings” was developed. The proposed measurement setup involves mounting the control unit of the string wave gauge at a height of several dozens of meters above the “strings”, facilitating convenient installation above water for measurements from a bridge or a sea platform.