Rubbish in Garbage out

Using a chart plotter to deal with secondary port tidal heights is a stunning improvement over the old number-crunching arrangements. However, if you need real accuracy, the bad news is that these predictions do not always concur with one another, neither are they always in accord with the official Hydrographer’s tide tables. You must ‘pay your money and take your choice,’ but when the chips are really down, YM is inclined to go along with the hydrographer, so if you’re cutting it to the wire, it’s back to the tide tables and interpolation.