In a message dated 7/4/99 9:58:46 PM, michaelbholt@juno.com writes: <<I've asked before about a device that would listen for a frequency common to all outboards, as a warning device for submarines. It would be simple to build. Anyone ever heard of this? >> No, but it would need to be directional to make any difference. You can hear an outboard for a long way from u/w already. V