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Why do the Inshore currents in Worthing seem so erratic and not follow the more normal tidal flow rules that you'd expect?

For well over thirty years, I've been an active windsurfer/kite surfer and now wing-foiler here in Worthing, and to be honest, the currents that do exist rarely affect me when I'm skimming across the sea.

However, in the height of the Summer, or more recently, the beginning of June, in the periods of calm, I also swim in the sea, without a wetsuit, and as someone who has been relatively competitive in cycling and running, I don't just go in for a "dip" but I do like to aim to complete a target and/or distance.

That used to be the yellow buoys 500m offshore, as I always thought if I had equipment failure out to sea, at least I knew I had the capability to swim back in :)

When swimming out to the yellow buoys, I'd often find that when coming back in, I'd end up a good 500m or so from where I started, such were the vagaries of the current. 

And way back when, I was never ever able to work out if there was "a best time to swim"  as it seemed there was never a period of slack-water, which people often refer to.

I did try Googling and even spoke to some local Dive companies, but on the whole they focused on currents well off-shore to where I was swimming.

In the end, to alleviate any stress/confusion, I often just went in the sea and swam in the direction wherever the current took me and then walked back along the prom, or lately knowing that the current often flowed East (Lancing) to West (Goring) I'd cycle down to Coast (past Splash Point) leave the bike there and swim back.

With the advent of SUPs, the issue of currents became obvious again, as we often paddled under/around the pier, going to Coast or Perch on the prom and encountering currents and chop, though it has to be said the currents are nowhere near as frustrating on a SUP as when swimming.

So with the recent heatwaves(s) I have been doing more regular swims, to the pier and back and monitoring my times, rather than just cycling down and swimming back.

And that's been quite an eye-opener, as the timings of the current bear bear no real relation to the theory out there.

So what is the theory?

It is generally accepted that the tidal flow timings are such that when the tide turns, so does the current, and the accepted timings are based on High Water at Dover, which, as it happens, is pretty well the same time as Worthing.

So this image shows the estimated speed and direction of the tidal flow 2hrs before High Tide.

The two digits 05.09 between Littlehampton & Shoreham are the estimated speed in knts on a Neap Tide (weaker) and a Spring tide (stronger), and this is important.

A short thin arrow shows a weak tidal stream; a fatter and usually longer one shows a faster one.

Spring tides are when the tide comes in and goes out the furthest, so there is a large tidal range, and that basically means there's much more water flowing up and down the English Channel, which results in faster speeds of the current.

However, as I have discovered on many occasions, the above is not the case when swimming inshore, and the chart and timings above are totally inaccurate for our stretch of the Coast, for as you can see, it is showing that 2 hours before the tidal stream is flowing West to East, Littlehampton to Shoreham.

The real situation is that the current switches to the opposite direction, East to West, Shoreham to Littlehampton at least 2-3hrs before!

 When researching this, using ChatGPT and providing it with my own actual experience of swimming here, these are some of the factors suggested as to why the current does not follow the theoretical norm, as it were.

With the tidal stream as the most likely explanation, due in part to the hydrodynamics of the central Sussex coast.

As around Worthing, there is a persistent west-going longshore tidal stream that often begins about 2 hours before high water and can be surprisingly strong, even close to the beach, with  local effects such as:

The beach is shallow for a long way out, so the tidal flow is squeezed through a relatively narrow band of water.
Groynes can accelerate the flow between them.
The irregular seabed can create faster "lanes" of current only a few metres offshore.

 So what's that mean in Black & White?

Over a number of swims, I have monitored my times using my Garmin Epix watch and Strava and have seen a dramatic difference depending on whether the current is with me or against me.

The above timings are from one of my swims (a good two hours before High Tide) from WeatherCam HQ to under the pier and back, and you can see how it's almost half the time on the return leg. I have similar numbers from swims to and from the Lido and along down towards the Canadian Memorial.

Out of curiosity, I did one swim to Coast Cafe, but four hours before High Tide, to confirm that the current was indeed still going towards Lancing; with the net result of having to walk a long way out as it was mid-low tide, and there was not enough water for quite a way before I could actually swim, and even going under the pier (three stanchions from the end) I nearly grounded!

And looking back at my data, it would seem the current switched, as I became progressively slower in the last 500m, or I was just getting tired, but this could point to the current doing it's thing 3.5hrs before High Tide?

 

I should also add that I swam in both directions along the coast here when the wind was blowing from both the East and the more usual West to determine if there was any major difference.

What I must say again is that for the vast majority of swimmers who merely want a dip, then currents will not be critical to them, but at least should they read this they will now know :)

And the same is true for the vast majority of SUPs, however, a very large % of water users tend to go into the sea within three hours of High Tide, so in reality, you will also have the current against you if heading towards Shoreham from Worthing.