it's partly because of things like the postcode being on the wrong side of the cut etc that the map displays a second marker showing where the centre of the nearest postcode is.
if anyone has a dataset containing lat/long for water points, pump-out, fuel, marinas, chandlers, VM's etc I could quite easily add the options so that it can display the nearest of them or display a rolling map showing everything within a few miles radius.
Note that this and the other project that I am working will free for all to use, will contain no advertising and will never earn me a penny (just in case anyone assumes this is some way of gaining a large dataset for commercial purposes)