I just use the 2 eyeballs in my head. In all seriousness, I fish for catfish in my boat, and have the rods either tight-lined and leaning against the inside of the boat at a 45 degree angle or in rod holders if I am targeting flatheads. A close friend of mine swears by the bells, even in my boat. He even insists on putting them on my cat rods.
There are some very nice and pricey bite indicators (electric ones) with sound and lights that allow the fish to run off line with a bit of tension. Lots of carp guys in Europe use them. You-tube has demonstrations of these. If I were a shore fisherman I might try one out.