
Originally Posted by
Max
Some Liverpool documentry on yesterday went on about the Mersey being a crazy place to put a port strangely too but the Mersey handles ships no problem.
200,000 ton tankers pass the Liver Buildings. The Mersey is one of the few rivers that is not funnel shaped. The river has narrows which widens out to a large estuary basin. The 4th highest tidal range means water rushes past the narrows between Liverpool centre and Birkenhead. This rush of strong current water keeps the narrows clear and deep - a tidal scour. Sand from Liverpool Bay is dumped in the estuary basin - it is taken out on the ebb tide. Why the Mersey has that brown colour to the water, except when the tide turns and it is still. The Mersey is only place on the north west coast where a large sheltered deep water port can be located.
The port is well sheltered from the Irish sea winds and storms. In the olden dayes, ships were not that big and the depth did not matter too much. The shelter and easy overland access to the towns in the hinterland mattered. Also, smaller barges (Mersey flats), could sail way inland, up the Mersey and Weaver, and even up canals.
div>
The port got bigger and better when the steam engine was invented and docks could be impounded (deepened) and large river-lock gates opened and closed. All this would be useless unless the river was naturally deep as ships became much bigger with deep draughts below the waterline - unlike todays ships which have shallow draughts and flat bottoms.
Many important and busy ports virtually disappeared when the steam engine and large ships came about, Lancaster and Bristol to name two.
Entering the port was difficult as ships tended to sail past the end of the Wirral and turn right into the river - over time sand banks shifted, so channels shifted too. Some came in via Formby point which was a straight run in. Large ships could only sail in via Formby. The Crosby Channel was deepened and underwater training walls built, which create a strong current, to keep the channel clear. This is the prime run in now.
Bookmarks