Want to use your computer to predict tides? Go to this web-site: http://scilib.ucsd.edu/sio/tide/

Tons of choices (most are free), plus a small write-up on tide physics.

After this step you buy a used 250-350 MHz lap-top for around 300 dollars, download the tide freeware, download the GPS mapping freeware from sping.com, buy a 100 dollar GPS from Wal-mart, hook it all up and become your own floating laboratory!!!