Yeahbut(r) that still doesn't explain the Poole Harbour phenomenen.
As I understand it, semi-diurnal means that you get the high high water, low high water, high low water, and low low water across the course of the tidal day (ie 24 hours ish). In Poole Harbour you still get the twice daily high tide eg at 7.00am and 7.00pm (approximate), but in each 12 hour period you will have 1st high, 1st low, 2nd high, 2nd low. The 2nd is high is your main high water. Basically, it comes in a bit, goes out a bit, comes in all the way and then goes out all the way, completely throwing out any rule of twelves! So, what would that be? Or is it just that all the curves and technicalities are getting me confused?
As far as I'm concerned, as long as I know what times they are, where and when the flow is strongest and which direction they're going in relative to my course so that I can make sure that I use them to maximum effect, I'm happy!
