You can add another transducer but we had problems with two transducers using the same frequencies interfering with each other. We solved the problem by going to a smart transducer that uses a different freq., I think 233hz? That solved the problem of one or the other of the sounders randomly not showing a reading (usually as we were going into shallower water).
SV Laurie Anne
1988 Brewer 40 Pilothouse