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GUIDE TO CANOEING IN CORNWALL Contd.

How the tides work in Cornwall

Introduction

Cornwall is one of those few places in the UK where the tide splits on its way in; up into the Atlantic/St Georges Channel and across into the English Channel. On the way out the two different flows interact complexly. This leads to some interesting and powerful tidal flows. As a consequence some places are much safer to paddle than others.

Example Diagram 13: 	 Tidal Hour approx 6 hours after high water Devonport The importance of Tides

Canoeists generally want to know the time of the tide, its direction, speed and also how much water will there be. The latter factor is particularly relevant in places such as the Fal on the south coast where it wpuldl simply not be possible to land when the tide was out due to impassable mud.

Tide tables

The time of tides can be sourced in a number of ways. There are the yellow tide tables available in most newsagents and beach cafes, which give the tide times at Newquay, with a set of tables to show how other locations in the county differ, there are others based Falmouth tides – often available from Chandlers. They should give the times and heights of high and low water along with the moon phase so that it is possible to tell whether the tide is a spring or a neap, the former occurring two days after a new or full moon. For those who need to navigate it is worth purchasing a tidal almanac. The Reeds PBO Small Craft Almanac is very good value in 2010 at £16, and gives sufficient tidal information to navigate your kayak or sailboat anywhere in Europe – and a lot more. Also really useful is “Mobiletide” a programme for a WAP enabled mobile. At £5 is is well worth downloading from the Cornish company; “ A Short Walk”. Whatever you use make sure you have made adjustments for summer time if indicated.

Strength of tides

The speed of tidal flow or current, and range (height difference between high and low water) of spring tides is generally twice as much as for neaps. How to calculate the range and flow of tides at any particular time and date, although quite simple is beyond the scope of this guide to canoeing in Cornwall. The reader is referred to the many books on the subject; the RYA Day Skipper course or the navigation module of the BCU 4* award.

Strength and direction of tidal flow in different locations

This information can be accessed in two ways, the tidal diamonds in Charts of the Cornish coast, or tidal atlas – see resources. Even if you use a tidal atlas, a chart of one form or another will be necessary for navigation. If you simply need to know which way the tide is flowing and for how long, with some idea of the speed range then the thirteen diagrams at the end could be of assistance.

Incoming tide in Cornwall

The incoming tide starts to flow up the north coast first, whilst the outgoing tide is still flowing out to the north west from the south coast (five hours before high water Devonport); in fact for two hours in this period the outgoing tide on the south coast is pulled round Lands End and up the north coast by the incoming tide already flowing up there (diagrams 2 & 3). The incoming tide only starts to flow consistently eastwards up the South Coast some three hours later in the third tidal hour before high water Devonport (diags 4 & 5 below).

Outgoing tide in Cornwall

As you would expect the tide turns to ebb on the north coast first, in the first tidal hour after high water Devonport (1hour after high water) first noticeable with a large eddy to the north of Penwith (diag 8). In the next tidal hour (two hours after HW Devonport) we have the reverse of what happened in the early stages of the flow: the outgoing tide sweeping out to the south west on the north coast is swept round Lands End and up the English Channel to the East by the remnants of the incoming tide still flowing to the east up the English Channel (diag 9 below).

Using the thirteen diagrams that follow

The diagrams that follow (in PDF format to open alongside, print off or download) show the direction of the tide in Cornwall for each tidal hour of thirteen stages of the full cycle. The speed of tidal stream is not specified, the rate of flow is simply broken down into whether it is above two knots, between one and two knots, or up to one knot, all applying to spring tides, the flow at neaps being approximately half the spring rate. Be aware that “above two knots” can mean up to 5 knots in certain areas!
Each page refers to a tidal hour corresponding with high water Devonport, upon which the Hydrographic tidal atlas is based. To relate this to local tide tables, remember: both high water Falmouth and high water Newquay are approximately half an hour before high water Devonport.
A tidal hour covers the period half an hour before and half an hour after the stage of tide referred to in the diagram. Thus the tidal hour “high water Devonport” covers the period half an hour before high water to half an hour after high water Devonport. From your tide table or almanac the time of high water on a particular date can be determined, and the tidal hour added or subtracted, so that the actual time referred to in the chart determined.

An example

If we wanted to know what the tide was doing around Cornwall at 3pm GMT on March 15th 2010, the first thing to do would be to look up the nearest time of high water on that date. A look at the almanac shows that the nearest high water Devonport on that date to be 18.30 hours GMT (6.30pm). As explained in the previous section, the high water tidal hour would be from 6pm to 7pm, one hour before high water would be from 5pm to 6pm and so on. Thus 3 pm would fall in the tidal hour 3 hours before high water. If you have only Newquay or Falmouth tide tables available – Remember they are both half an hour before Devonport, so half an hour would have to be added to them to locate the corresponding Devonport time.

Limitations of the following information

  • Cannot be used to plan any trip in which the actual rate of tide is needed at any hour
  • Intended as a rough guide only i.e. to assist the reader’s understanding of how the tides flow around Cornwall
  • They advise roughly which way the tide is likely to be flowing at a particular stage of the tide
  • Know if the place you are intending to paddle is an area of strong or weak tidal flows (the guide is too broad to cover every location if in doubt ask a local or consult the literature recommended elsewhere)
  • This guide is based on tidal atlas, chart and Almanac sources, to be sure you need to consult these yourself
  • No responsibility can be accepted for any decision to go to sea based upon these diagrams. They are for general guidance only and cannot take the place of a properly used chart, tidal atlas and almanac.

    The Diagrams

    The following are links to the diagrams in PDF format for you to open, download or print:


    Cornwall Custom Kayaks PDF file Diagram 1: Tidal Hour approx 6 hours before high water Devonport (200 KB)
    Cornwall Custom Kayaks PDF file Diagram 2: Tidal Hour approx 5 hours before high water Devonport (360 KB)
    Cornwall Custom Kayaks PDF file Diagram 3: Tidal Hour approx 4 hours before high water Devonport (307 KB)
    Cornwall Custom Kayaks PDF file Diagram 4: Tidal Hour approx 3 hours before high water Devonport (365 KB)
    Cornwall Custom Kayaks PDF file Diagram 5: Tidal Hour approx 2 hours before high water Devonport (350 KB)
    Cornwall Custom Kayaks PDF file Diagram 6: Tidal Hour approx 1 hour before high water Devonport (334 KB)
    Cornwall Custom Kayaks PDF file Diagram 7: Tidal Hour approx high water Devonport (406 KB)
    Cornwall Custom Kayaks PDF file Diagram 8: Tidal Hour approx 1 hour after high water Devonport (340 KB)
    Cornwall Custom Kayaks PDF file Diagram 9: Tidal Hour approx 2 hours after high water Devonport (347 KB)
    Cornwall Custom Kayaks PDF file Diagram 10: Tidal Hour approx 3 hours after high water Devonport (361 KB)
    Cornwall Custom Kayaks PDF file Diagram 11: Tidal Hour approx 4 hours after high water Devonport (368 KB)
    Cornwall Custom Kayaks PDF file Diagram 12: Tidal Hour approx 5 hours after high water Devonport (379 KB)
    Cornwall Custom Kayaks PDF file Diagram 13: Tidal Hour approx 6 hours after high water Devonport (253 KB)

    Acknowledgements

    Based on the Admiralty Tidal Stream Atlas, Falmouth to Padstow including the Isles of Scilly (NP 255 Edition 1)(pub The Hydrographic Office, Taunton, 2004)
    Charts:
              Imray C7, Falmouth to Isles of Scilly & Newquay
              Stanfords Yachtsmans Allweather chart !£ Start Point to Trevose Head

    Resources:
    Inshore Britain, Stuart Fisher, Imray Laurie Norie & Wilson 2006
    Small Craft Almanac, Reeds Practical Boat Owner, Ed Du Port & Butress, Adlard Coles Nautical
    Mobile tide tidal prediction pragramme for WAP enabled mobile phone:     
    www.mobiletide.co.uk/
    Newquay and Falmouth tide tables available from most newsagents and chandlers.



    onto Canoe Clubs in Cornwall


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