Don’t get caught out by the tide

It sometimes takes visitors by surprise how big the tidal range is at Chiswick – over five and a half metres – and because of the shape of the tidal river the tide takes twice as long to go out as it does to come in. People are often amazed at how quickly it rises.

The RNLI has a lifeboat station in Chiswick, which is the second busiest in the whole of UK and Ireland. Former lifeboatman David Clarke says the crew often find themselves rescuing people cut off by the tide.

Read his blog here: Tideway Tales

RNLI Chiswick say the water on this stretch of the Thames is particularly tricky:

“The tidal cycle on the upper tideway is very different from the coast. The flood tide takes only four hours, while the ebb tide takes eight hours. This means that the tide rises very quickly and has resulted in many people being cut off by the tide on the foreshore and on islands. The asymmetric cycle also means that flood tide current can exceed 4 knots.

“There are also very unusual conditions after prolonged periods of heavy rain in the Thames catchment. The current on the surface runs downstream even when the incoming tide is making the river level rise. This means people parking close to the river mistakenly believe the tide is going out and water levels are falling. Chiswick lifeboat crews have attended many flooded cars over the last 20 years.

“A third anomaly occurs when the Thames barrier is raised to keep out surges in the North Sea; then there is little change of water level and tide tables become irrelevant.”

rnli.org

Our Thanks to Richard Jennings

Our thanks to Richard Jennings who previously provided tide time data for the Chiswick Calendar. We have since developed our own system to generate tide time data for Chiswick Mall and Strand on the Green, building upon his methodology. We continue to employ his technique of calculating local tide times by estimating the speed of individual tides based on predicted times at Chelsea Bridge and Richmond Lock, rather than using average calculations. This method provides more accurate tide predictions for both high and low tides.

Further information about tides on the Thames in this part of London is available online at thamestides.org.uk

In particular, real-time information on what is actually happening on the Thames, including current tide levels and fluvial flow, the Barrier status and details of any active flood alerts are available at thamestides.org.uk/now