The Princes Channel has, however, always been the shallower of the two. For  many years the North and South Edinburgh Channels and, following their silting up, the Fishermans Gat, were convenient alternatives to this southern route, offering greater depths and avoiding having to go ‘round the top’ and down the Black Deep.

Among the disadvantages of these channels were the longer journey times over the Princess Channel due to the introduction of a dog leg and, as they are at right angles to the tidal flow, their gradual silting up at each end.

The decision to dredge the Princess Channel has several advantages. The shorter route is of course obvious, with the PLA reporting that ships will save around eight miles sailing time by removing the dog leg, equating to a combined saving of around £185,000 worth of fuel and,200 tons of carbon dioxide emissions a month.

Another advantage is the route is seen as a safer option because ships emerging from the inward end of the Fishermans Gat channel have to cross the Black Deep before turning to continue inwards. The Princess Channel is a more direct route, in effect ships will merge with the other channels motorway slip road style rather than entering at right angles from a ‘side road’ at the Fishermans Gat.

As well as the gradual increase in traffic in general, the increasing size of container ships requires that the ports infrastructure keeps pace with progress. The two main container terminals in the area, Tilbury Container Services at Northfleet and Hutchison Port Holdings Thamesport container terminal on the Medway are both keen to attract larger tonnage and recently congestion elsewhere has seen both ports handle diverted ships significantly larger than their usual regular callers. In addition the long awaited go-ahead has recently been given for the huge London Gateway container port on the site of the former Shell oil refinery at Shellhaven, heralded as London’s biggest port project for over a century.

The six to eight week dredging project (the port's biggest for 40 years) is due to start this autumn and will see the equivalent of 70,000 lorry loads of sand removed and discharged into  the disused North Edinburgh channel. The PLA’s Derek Maynard, who is in charge of the project said, 'The improved Princess Channel is excellent news for more than 2,000 vessels that currently use the Fishermans Gat. And it will make the Thames a more attractive destination for ships coming in from the Strait of Dover because getting here will be less hassle.'

By Peter Barker