[Gllug] River Thames

[Philip Davies]

On Tue, Jul 12, 2005 at 06:52:35PM +0100, John Hearns wrote:
> On Tue, 2005-07-12 at 15:20 +0100, t.clarke wrote:
> > If anyone has a view of the Thames up-river of Dartford Crossing, and
> > is interested, an aircrafyt carrier with a Harrier up front is coming
> > up the THames presently (just passed Northfleet/Tilbury).
> 
> Woo!
> The last time, the Hermes anchored off Greenwich, at the liner terminal
> which is at the mouth of Deptford Creek.
> I gather such a large draught ship cannot get up further.
> And it was a very, very low tide earlier today (anyone nautical
> care to explain why?)
> 
The BBC web site provides some excellent information, here's their 
explanation:-

  Q. What are "Spring" and "Neap" tides?
  Spring and Neap tides are created by the relationship between the 
  Earth and the Moon during each lunar month. Spring tides occur 
  shortly after New and Full Moon, and Neap tides occur shortly after 
  the Moon is in its First and Third Quarter.

  Spring tides occur when the gravitational forces of the Sun and Moon 
  reinforce each other resulting in a higher than normal tidal range. 
  Neap tides occur when these gravitational forces act at right angles 
  to each other resulting in a lower than normal tidal range. Spring 
  tides are nothing to do with the season, but it is believed the name 
  is derived from a medieval word to "leap up". Neap comes from an old 
  English word for "low" or "to nip".

There is lots of other info on tides at:-

  http://www.bbc.co.uk/weather/features/coast_sea/tidesfaq.shtml

Checking the Almanac, high tide this afternoon would have been at 18:02 
at Deptford Creek, low tide should be about 00:22. Springs were on the 
8th, Neaps will be on 16th so we are about half way in between at the 
moment, 

If you want to see a tidal graph for London Bridge:-

  http://www.bbc.co.uk/weather/coast/data/20050712/0113_20050712.shtml#graph
-- 
Regards
Phil
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