That was what I thought you meant. And yeah that was pretty much exactly what I was thinking. If the current was pushing against the rudder in waves it would

That was what I thought you meant. And yeah that was pretty much exactly what I was thinking. If the current was pushing against the rudder in waves it would also make a rhythmic pitch change that went along with the water movement. If the whales hit the rudder it makes a "whine"...which is what an animal might do as well.