Magic Seaweed explained for Sea Swimmers

Brilliant Blog by Freyja Hunt – how to read magic seaweed to aid sea swimming choices

This is a brilliant blog by Seabird Freyja. Everyone has a different favourite forecasting app that they use to see if it is safe to swim. The most commonly used app is Magic Seaweed that was designed for surfers see what swell was approaching but it can be used to look at sea swimming conditions too!

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Magic Seaweed (MSW) surf report provides a seven day forecast of sea conditions. Here’s a guide to understanding the data so you can get a better idea of what to expect before heading down to the beach.

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Surf

This is the first column in blue. In Brighton and Hove, this is essentially the height of the shore break (or the white bits that can knock you over). This will give you an idea of how difficult it will be to enter and exit the water. MSW is designed for surfers so the measurement used is that of the surfable wave rather than the total wave height. For us sea swimmers it might be worth adding a little extra on to this measurement.

It is worth noting that the value given is the average height. 1 wave in 23 is likely to be twice the average height and one in 1,175 is three times the average height. Therefore, it is worth taking this as a rough guideline and always be on the lookout for larger waves when getting in and out.

In terms of height of the shore break, my rule of thumb is anything above waist height is capable of knocking me over.

 

Swell

Swell – listed in the second column – is the height of the waves once you are past the shore break. A big swell can be a lot of fun as you bounce around above and below your swimming buddies.

The next column gives an indication of the wavelength, or the time between the crest of each wave in seconds. The longer the time, the gentler and more undulating the waves will feel. Conversely, shorter times between each crest means the waves will come more frequently and you may be more likely to get a mouthful of sea water.

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The black arrow to the right is an indication of the direction the swell is travelling. If you are doing a point to point swim, this is worth bearing in mind – if the swell is travelling in the same direction as you, it will feel like it is pushing you along. If you are swimming into the swell you will again, be more likely to get lung-fulls of sea water.

 

Wind

Wind is the main factor influencing how rough the sea is going to be. The stronger the wind is and the longer it has blown for, the larger the swell is likely to be.

The right-hand number column denotes wind speed. The larger number being the steady wind speed, and the small number being the gust speed. The arrow shows the direction the wind is travelling in. In Brighton and Hove the prevailing wind is South Westerly.

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It is worth considering that MSW doesn’t factor in local sea breezes. Sea breezes are caused as the land changes temperature faster than the sea. For example, in the morning the sun heats up the land quicker than the sea. This triggers the air on the land to rise up and and cooler air is drawn in from the sea to replace it. Sea breezes are generally onshore in the afternoon (as the land heats up and air rushes in from the sea) and offshore in the morning (where the land falls below sea temperature overnight and air moves from land to sea).  You might therefore expect the wind to be slightly stronger in the afternoon than denoted on MSW.

 

Tidal Information

Magic Seaweed also shows the times and heights of the high and low tides. In Brighton and Hove, low tides generally vary between 1 and 2.5 meters and high tides between 5 and 6.5 meters above chart datum. The difference between the two is the tidal range. The tidal range has an effect on currents – the larger the tidal range, generally the stronger the currents will be. The tidal range during spring tide in Brighton is around 6 metres.

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In a nutshell

The first column is the height of the shore break and gives you an idea of how difficult it is to enter and exit.

The second column is the height of the swell and tells you how bouncy it will be once you are in and past the shore break.

The third section tells you wind speed and direction – or the best direction to swim in to avoid getting a mouth full of sea water.

The box below informs you of the times of high and low tides and the tidal range. From this, you can have a go at working out the direction and strength of the current.

 

See, didn’t we tell you, a brilliant blog. Thank you Freyja for allowing us to host it on our site. I use Wind Guru, Nautide and Imray too!

Like Mother Like Daughter

An extract from a Seabird mum’s diary from 1980 – wild swimming is not a new thing!

The Diary of Ann Steward

This week I received a letter in the post from my mum. There is nothing unusual in that. I often receive letters, cards, newspaper cuttings and books in the post from my mum. She is fierce in her protection of the analogue and unless I put pen to paper, literally, she will never read any of these blogs. Which is a shame as this one is about her!

So the letter I received was short and to the point. That is my mum in a nutshell. “Dear Katharine, Looking thro’ my many ‘diaries’ I came across “A Selsey Summer” written in the 80’s? I thought you might enjoy this extract. Obviously you have inherited your love of the sea and swimming from your Sainted Mother! Lots of Love.”

To put the extract in context – my mum was a school teacher – and every school holiday we would relocate to Selsey, West Sussex and live in a converted railway carriage on the beach, called Nutshell, with all manner of foster siblings, cousins and anyone else that my parents swept up into their very un-nuclear family.

“We’d swum everyday – to begin with there was time to get in two swims – one before lunch and one after, but for the rest of this week we’d have to wait until 6/7 o/c for deep water unless we cared to try for a swim early morning. 

I was better than ever at ‘getting in’. I still needed that preliminary paddle up and down to knee height, then up to the middle and a pause before a step or two to reach my armpits when I could bob down and launch into my school girls breast stroke.

It was always worth it – even if on a chill, sunless day you didn’t stay in too long. What a feeling of wellbeing – superiority and freshness it gave. Half a dozen strokes towards the breakwater – half a dozen back, bob up and down and repeat. 

The most important purpose of the daily swim was to timetable the day. It set an immovable hour in the day – for it took that time on a chill day and twice that on a hot one, to follow the ritual of gathering the party – pulling on costumes, finding towels and in the case of adults forcing feet into still damp plimsolls as protection from the shingle. 

What time’s high tide? Then we must have breakfast/lunch by such and such. before our swim we could do this and after the swim we’ll do that. And so our day was mapped.”

I remember my mum wrote diaries. I remember our endless summers swimming in the sea. I remember days dictated by tides. I remember how bloody long it took her to get in – but she always did – eventually. And still does. But, I’d forgotten that this life that I live is not new to me. It’s always been my life, me and the sea. All I’ve done is remember and come home.

Author: Seabird Kath

3 generations of Seabirds

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The extract goes on to say ” A couple came to look over ‘The Summer House’ next door which is for sale. They have left their large expensive motor outside Nutshell while they have the guided tour around the quite extensive grounds. How well I remember it years ago when the old gentleman lived there as a recluse. The garden overgrown – little of the house visible, fruit trees laden in the Autumn, banks of primroses in the Spring. We’d dreamed of it being ours.” It never ended up being theirs but they have a beach hut and home on the Isle of Wight now – which I am sure comes a close second.