xtide is a program which predicts and displays tides.  It is capable of
producing output in a variety of dynamic and static formats, and has
extensions for X, plain ASCII, and HTML.

You may need to replace the harmonics file used by this port by one
better suited to your area; there are a number of harmonics files
available at http://www.universe.digex.net/~dave/files/.  You will
also have to specify your location either by setting the LOCATION
environment variable, by using the -location script, or by creating
an appropriate ~/.xtiderc. 

http://www.universe.digex.net/~dave/xtide/xtide.html has complete
documentation, or just read the man page.

- Brion Moss
brion@queeg.com