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In the first instalment of our Sea Signs series, William unlocks the secrets of the moon and shares ways that observing its phase can enhance your adventures.


This feature is one of twelve, with each focusing on an element around the coast that you should have on your radar. Why? Because they are all telling something about what is going on and perhaps more importantly, what is about to happen. With  that knowledge you can better prepare for what's coming next; whether it’s reefing the  sails before a squall, padding out the way of a big set of waves, avoiding getting cut  off by the rising tide or escaping an impending tsunami.

1. THE MOON.jpg


Before we set sail in Luna and became ‘sea nomads’ we lived in Deal, a small town in Kent famous for smuggling, castles and ‘the Downs’ - a natural anchorage where hundreds of ships took shelter in the days of sail while waiting for favourable winds to take them down the Channel and into the Atlantic. There are few sailing boats to look upon now, but being east facing the beach enjoys a sublime view often overlooked in today’s world; the moonrise. There’s something magical about watching the moon rise - it could easily happen without you noticing, it seems to appear at wildly different times every day and for half the month you can’t even see it because of the sun’s alignment. It’s this rarity that makes catching one so unique, watching it gently drift above the horizon with an elegance matched only by its pull on our seas.


Before I get carried away talking about the power of the moon, let’s start by going through the four main phases. The first thing to remember is that the moon doesn’t emit any light of its own – it simply reflects sunlight – and the face being lit up tells us what phase we’re in. Once a month the moon orbits the earth and we start with the ‘New Moon’, dark in the sky because it’s directly between the sun and earth so we can’t see the face being illuminated. Seven days after the New Moon you will notice the right half of the moon is lit up; this is the ‘First Quarter’ phase, named because it has completed the first quarter of its monthly orbit around us. A week later the whole moon is visible so we call it the ‘Full Moon’. Seven days after this and three quarters into the monthly lunar cycle we experience the ‘Third Quarter’ when the left half is lit up. A week later we return to ‘New Moon’ and the cycle repeats itself. 

The moon phase has a huge effect on our seas. During the New Moon and Full Moon when the earth, sun and moon are aligned the combined gravitational pull from the sun and moon is enhanced and this creates more powerful tides with higher highs, lower lows and faster currents – a time called Spring Tides. A week later, when the moon is perpendicular to the sun and earth, we experience weaker tides called Neap Tides [meaning without power]. A week after Neaps the sun, moon and earth are re-aligned and we return to Springs. These fortnightly Spring Tides – nothing to do with the season - are so powerful that they create astonishing natural phenomena; the mesmerising Bitches standing waves in Wales, the awe-inspiring Corryvreckan whirlpool in Scotland and the infamous Severn Bore in England, to name just a few.


A few years back, I had the privilege of experiencing the Severn Bore with Steve King, a railway engineer from Gloucester who has been surfing the bore longer than I’ve been alive. Steve is a Guinness World Record holder for riding the wave 14.5 kilometres upstream, a feat made possible by the rising tide being funnelled into the Severn Estuary until the pressure is so great the water bursts forward and surges up the river in the form of a 2-metre wave. Unlike most people who choose their days off for the weekend, Steve times his for the New and Full Moon phases - regardless of what day of the week it is. And when there’s a rare Perigean Spring Tide [when the New Moon or Full Moon happens at the time when it is closest to the earth on its elliptical orbit] Steve makes the most of the enhanced gravitational pull and treats himself to a holiday exploring other bores around Britain; the Dee, Arnside, Humber – Britain has the highest concentration of them in the world. 


Tidal Compass prints are works of art for home that help you stay smart at sea.

Not only does the moon affect the power of our tides, it controls the timings too. For example, the Severn Bore always appears around 9am & 9pm. And with a little research you can learn the tide times for your local beach; at the next Full Moon write down the time of high tide and check it on the following Full Moon – it will be within an hour. And it should always be like this, for the rest of your life. The theory goes that because tide times are 50 minutes later every day, over a lunar month this adds 24 hours [50 mins x 29.5 days = 24 hours], so tides essentially ‘reset’ themselves. And by learning the time of high tide for Full Moon you can apply it to any moon phase; during the Third Quarter a week later simply add 6 hours [50 mins x 7 days = 6 hours]. And to find Low Tide simply add or subtract 6 hours from high tide.

“remembering the time of high tide at Full Moon means you can predict the tides for any day of the month”

In Deal, where we lived when I wrote The Book of Tides, low spring tides always happen around 6am & 6pm, a crucial time because the especially low tides create the effect of a set of tidal islands rising out of the sea five nautical miles offshore. These are the Goodwin Sands, mesmerising and treacherous in equal measures. I used to work for a company called Dover Sea Safaris and we would take people on trips out to the sands, dropping them off for an hour of splendid isolation, all alone except for a colony of seals. On the morning trips someone would always ask bleary-eyed why we had to go so early – couldn’t we leave a little later? It’s not down to me, I would answer, it’s the moon who sets the time. On one occasion we were navigating through channels amongst the islands and our sonar showed a funnel shaped hollow in the sand directly beneath us. Right out the middle of it a single structure rose straight up; a mast – one of 2,000 recorded shipwrecks in just a few square miles. 


The powerful tides in the English Channel are constantly shifting the Goodwin Sands and uncovering the wrecks of WWII bombers, merchant ships laden with silver and seventeenth century Man-O-Wars. This creates a natural playground for scuba divers, but it takes a special breed to enjoy exploring these cold, murky waters with currents so swift you have to hold on to the wreck to avoid being swept away while the visibility is so poor you can’t even see what you’re holding onto. One of my friends, Mark Baites, thinks the rewards are worth the risk and has a way to minimise the danger; diving on the days around the First Quarter and Third Quarter moon phases when the currents are weaker. So while Steve King is surfing the Severn Bore during Springs Mark is working, and when Mark takes his days off to scuba-dive the Goodwin Sands during Neaps, Steve is back at work waiting for the next Spring Tide. All of this you can work out simply by looking up at the sky. 

In the next Sea Signs feature William will explore the depths of knowledge you can uncover by simply observing the time of high tide.

About this series

Every day the sea is different, a  result of the ever-changing interaction between the moon, sun, tides, wind, waves,  buoys, boats and the beach. While the picture may appear complex, like a piece of classical music, it is essentially just an arrangement of simple elements, or notes. By dismantling the machine into its component parts and exploring each one in detail we can create order out of chaos; clarity out of confusion. That is the  purpose of this series 'Sea Signs'.

When we are young we learn to navigate urban environments; what traffic lights  mean or how to cross a road. What many of us aren’t taught is how to read nature’s  signposts; how to judge wind by watching birds or what weather different clouds  bring. Then there’s a whole technical world of buoys and boats with different light  sequences, colours and signals communicating messages. My goal in this series is to  share with you all the signs – both natural and man-made - that you may encounter in  your adventures along the coast so you can read them as well as any yachtmaster  skipper or crusty old seadog. 

With this knowledge, nothing is going to slip under your radar.

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