I have a few more sugestions:

If you want to have a tide chart on your PC, Tumonz has a free tide chart program you can upload, it's about 1.4meg. http://www.tumonz.co.nz/downloads.php?page=Tide%20Viewer

Or you could do what I do and use your WAP function on your cell phone. I use http://www.ofu.co.nz/wap/ and find the area you want. I keep my area as a bookmark on my cell. I have just had another look and it only gives 21 locations and none for 90 mile beach on this wap site.

There are also tide books available at your local sports shops by area too.

P.S. www.ofu.co.nz is also another easy to use net tide search.

May the wind be with you!