I think that the idea of using ELF or VLF will probably not float (Pun
intended). We live near one of these antenna and it's about 1/2 - 1
mile long. Probably the idea of a float bouy with a small antenna would
work.

PS I'm not an RF expert so take it with a handful of salt.

--
Neil Cherry     http://home.att.net/~ncherry    ncherry@worldnet.att.net