That's not the tunnel drive . That's the smooth hum of rigging on the port side of the boat . Not sure if this means anything , but there is a ton of what look like niagria minnows . Or smelt loaded in frt. . of ibay. Clouds on screen in 20 fow . And prop. Churning them up for the gulls . Look like Alfred Hitchcock movie . Birds dive bombing everywhere. The Browns are full.