I have been using 10 heavy stainless steel washers (about 1.5 inches) tied to 20lb test every 3 inches or so and dropped to the bottom for years.
I tie them to the closest cleat. When the boat moves up and down from the waves, they make a metalic clicking noise as they hit the bottom.

I figured a massive clank from the big "perch callers" was too much for the fish when it got close.

Give it a try.

PS. it is cheap....