Hi Oldie,
If you want the waves to appear frozen then start with very little ability, put up a big sail in a big wind, and HANG ON!! Works for me

Also if you're after a tide clock a cheap one that appears to work is this one:
http://www.ratesaver.com.au/products/index.php?Operation=ItemLookup&ItemId=B0000AXOBI It's a Howard Miller clock, you might be able to pick one up locally. These seem like a pretty good deal on a tide clock, you don't pay for loads of polished brass or w*nky ships wheels.
Also here's another one for $89 + shipping:
www.tideclocks.com.au/index.asp?page=tidebf.htm