Did you check for kelp circles caused by the clustering effect of the vessel's exhaust ions on the sea water ? (it's a little known fact but the Penta Water actually "cluster" their water using an engine recovered in Florida from the UFO which shot down flight 451 - the whole Bermuda Triangle thing is just a cover). Fish swimming backwards is also an indication (apparently the EMF emissions really screw up their motor receptors - as well as causing Leukemia (unless of course they are wearing a magic talisman)).