Tides & Photography

Spurn Point, Yorkshire

Britain’s coastline is steeped in history and natural beauty making it possibly the most photographed coastline in the world.  Castles, Coves and Cliffs all make great photographic subjects that can give instantly pleasing results but if you want to perfect your images you need to plan ahead to get the tides right and for your own safety, so this is my little guide to just that. 

Generally speaking costal images are best made on a falling tide a) it’s generally a safer option and b) you get nice wet rocks & sand etc for added impact and detail in your images.  But certain locations require pinpoint accuracy, some secluded coves, for example, are inaccessible at high water.

Having lived by the coast for a good part of my life, and 15 years of Scuba Diving to my name, I feel quite confident around water but I never get complacent about it.  It’s all too easy to go out on a beach at low tide, be captivated by your photography, then find your exit is now awash with water.  Only on a recent trip to the Northumberland coast I was stood on some boulders while taking a series of images and you could see the tide moving in fairly quick and had I not been aware I would have soon been in water too deep for my welly boots to contend with.  These images were taken just 4 minutes apart and clearly show the rising tide.  The image on the right was taken with a 10 Stop filter to blur what little motion in the water there was.

The tides are governed by the gravitational pull of the sun, the moon and the rotation of the earth.  The Moon, being closer to us, is the more dominant factor.  We have roughly, there are exceptions, two high tides and two low tides in a 24 hour period.  Now, I’ll attempt to explain tides in simple terms for us photographers. 

These gravitational forces cause the water on the surface of the earth to bulge and thus create our high and low tides. When the sun and moon are at 90 deg to each other in relation to the earth these gravitational forces work against each other and this reduces the tidal range (a small bulge) – this is known a Neap Tides.  Whereas when the Sun and Moon are in line with the earth they work together increasing the gravitational forces producing a greater tidal range (a large bulge) – known a Spring tides. 

Image courtesy of “Curious About Astronomy” 

You may be asking what is the relevance of all this, well, during spring tides the tides are higher and lower than those of neap tides and thus produce a larger range of water movement.  So, if you want to photograph those old decaying Groynes on the beach you may want to avoid high water spring tides because they will probably be under water and conversely a low water spring tide will probably leave them high and dry.

Another variable to maybe consider is the movement of the water itself.  Photography has it’s rule of 3rd’s and tidal prediction has it’s rule of 12th’s.  At high or low tide there is very little movement of water, this is known as “Slack Water”, but as the water falls (an ebbing tide) or rises (a flood tide) its rate of change speeds up at roughly the mid-point of the tidal change.  The following table may help explain this;

1st Hour	1/12th of the total tidal movement
2nd Hour	2/12th of the total tidal movement
3rd Hour	3/12th of the total tidal movement
4th Hour	3/12th of the total tidal movement
5th Hour	2/12th of the total tidal movement
6th Hour	1/12th of the total tidal movement

You may again be asking what is the significance of this.  Well, lets say your down on the beach at low water, you’ve been there a couple of hours exposing images, your now at that point of a rising tide where there is the greatest amount of water movement.  In places this movement can be rapid enough to out pace your retreat up the beach or in other places, if you are on a higher sand bank for example, cut you off completely from the shore line. 

So, how do you avoid these mishaps and plan your shoot to have the optimum tide for your location?  You need to consult tide tables.  The are produced by a number of sources. 

Example Tide Chart

The UK hydrographic office produce tidal information that is published on the Admiralty web site, see below.  They are free for a seven day period but you can register and for a small fee and get tide times for any day of the year.  Most harbour offices sell locally produced tables and there is a whole host if sources on the web.  My favourite though is the National Oceanography Centre website which give free 28 day tidal predictions for most UK ports, have a look at their website here. If your photography is away from a listed port then an element of guesswork and calculated judgement is needed.  Using admiralty charts it’s possible to plot the tide for any given point, but, must of us dont have these nautical charts so you need to look at the port tide times either side of your location then you have a range from which to estimate your tide times.

Tidal charts are fairly easy to read and understand.  They give the times of high and low water but most times are in GMT so make sure during British Summer Time (BST) that you add 1 hour to the published times unless already corrected for BST, don’t get caught out by a simple error.  The other figures are the tide heights above chart datum, the lowest depth that the tide should ever reach.

So, there’s my guide to tides which  I hope will take some of the confusion out of tidal prediction and give you a little confidence when using tide tables to enhance your costal photography.  Remember, do you homework and you will have a safe and enjoyable day at the coast.

Here is a few resources that you may find useful;

National Oceanographic Centre	Free 28 day tidal predictions
UK Hydrographic office	Admiralty 7 day tidal prediction service
WXTide32	Freeware windows based tidal prediction software
BBC Weather Tide Tables	7 Day predictions from the BBC
Maritime & Coastguard Agency	A website full of useful information about coast safety and related issues.