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Paddleboarding River Estuaries – A Guide To Tidal River SUP

Posted by Lydia Burdett

River estuaries – sometimes also known as harbours or sounds – can offer some of the best paddleboarding conditions around, often providing shelter from the weather and protection from choppier open seas. As rivers widen and open up towards the coastline, they can be beautiful, atmospheric places to paddle too, so are rightly popular for SUP. However, there are a few hazards to be aware of and some careful planning to do before launching onto any tidal river. To help you prepare, here’s our guide to paddleboarding estuaries and tidal rivers…

Are Rivers Tidal?

Yes – while further inland, all streams and rivers will simply flow towards the sea, as they approach the coast sooner or later every river becomes tidal (ie; the water levels will rise and fall with the sea’s tides). How high upriver this phenomenon occurs will vary from river to river – often there’s a significant man-made structure, such as a sea lock or weir, below which the river becomes tidal. These tidal stretches of river don’t just get deeper and shallower through the day, but they flow in completely opposite directions and at varying speeds depending on the state of the tide – so sometimes they’re totally safe, whereas at other times they’re very dangerous places indeed. Before heading out onto a river estuary you really need to be sure of your timings…

Understanding River Tides

Whole books have been written on tides, and although there are various different types around the world, here we’re going to focus on by far the most common and ‘simple’ tidal pattern that governs most British tidal rivers and estuaries. A ‘semi-diurnal tide’ sees two high tides and two low tides each day split into roughly equal tidal cycles – so high tide and low tide are about six hours apart (eg; if high tide is 1pm, the next low tide will be c.7pm, then high at c.1am, low at c.7am, etc…) Actually, it’s just over six hours per phase, meaning high tide will get up to an hour later each day. These tide times are easily predicted and widely published – you can find them online, in weather apps, tide apps, the local newspaper, even on chalkboards outside coastal shops and cafés.

It’s important to understand that tides mean that water will literally flow into and out of the river estuary (from the open sea) – as the tide comes in, there will be a current pushing inland from the sea (ie; upriver). As the tide goes out the current will pull out towards the rivermouth and open water. And it’s the rate of flow that controls the strength of the current. The water will be moving at its fastest midway between high and low tide, and slowest at high tide and low tide itself. You can think of a tide like a pendulum, swinging out and in – midway it’s travelling at full speed, whereas at either end, the pendulum (ie; water!) needs to slow down, stop, then gradually start moving back the other way. This time – roughly a two-hour window an hour before and after high or low tide – is known as ‘slack water’ and is without doubt the safest time to paddleboard on any tidal river or river estuary as there’s little or no current. Whereas at mid-tide there might be much more current than you’re able to paddle against.

When To Paddleboard On River Estuaries And Tidal Rivers

As a rule of thumb, definitely avoid going paddleboarding on a river estuary or tidal river mid-tide (ie; the two hours midway between high and low) when the currents can be dangerously strong. The nearer to high or low tide you paddle, the less current there’s going to be, so paddling within a couple of hours of the tide is definitely a good idea. Ideally – and certainly higher up a tidal river, where it’s narrower and the flow will be increased – keep within an hour (either side) of the tide.


What About Weather?

Although usually better protected than the open sea, river estuaries definitely aren’t immune to the wind – in fact, if the wind’s blowing strong directly up or downriver, wind against tide effects can cause much more chop inside an estuary than out! If the wind’s blowing across a river estuary, then the banks can offer great protection from a breeze, often glassy water and no wind at all right by the shore. As always when paddleboarding, you need to know and understand the weather forecast – and appreciate what that means at your location. Never paddle in a stronger wind than you know you can cope with.

Route Planning

Essentially you’re trying to ensure that when you’re paddling home, everything will be helping you get there safely. So ideally, both the breeze and tide will end up pushing you back where you need to go. What you must avoid at all costs is having to battle back against a building tide (as the current accelerates towards mid-tide) and wind, because making headway will get harder and harder as you get ever-more tired – which is exactly how people get into trouble.

So an ideal circular tidal river route might start from a point nearer the mouth of the estuary, maybe an hour before high tide, paddle upstream (ie; inland, with the last of the tide helping push you upriver until the water goes ‘slack’) ideally into a little bit of breeze (ie; light wind blowing down the river, out to sea) to turn at high tide – then both the building ebb tide and tailwind will help you paddle back to where you started. Whereas think about what might happen in the same conditions if you chose to head the other way, out to sea first: you’d paddle downwind nice and fast when you weren’t tired, then turn at high tide to head back against both the building ebb tide and a breeze, in increasing danger of getting swept out to sea if anything went wrong or you started to run out of energy. Very bad news.

It might sound complicated, but you just need to know about two things: the wind and the water. What they’re doing now (ie; direction and strength of wind and current) and most importantly what they’re going to do next (ie; knowing your weather forecast and the tide times are critical!) Armed with that knowledge, work out your route to ensure that the paddle back home will be helped rather than hindered by the elements.

Sometimes of course the wind direction and tides don’t work out to allow a circular route (up and down the estuary) – in which case you could always do a one-way point-to-point route instead, leaving a vehicle at the end or arranging a lift back from your finishing point. For example, launching at high tide at a point higher upriver (ie; inland) with the wind blowing out towards the rivermouth, you can paddle one-way with the dropping tide and the wind at your back the whole way. Or vice-versa, if the wind’s blowing in from the sea, start near the rivermouth a couple of hours before high tide and ride the wind and tide inland.

Whatever you choose to do, ideally paddleboard river estuaries and tidal rivers in company – and always let someone know what you’re doing and when you expect to be back.

Navigating the River

Estuaries aren’t just a refuge for paddleboarders – many provide natural harbours for commercial shipping and domestic pleasureboats, so they can sometimes prove to be very busy places! On the whole, paddleboarders are best staying relatively close to shore and hence well away from shipping lanes, but you’ll almost inevitably come into contact with other traffic when paddleboarding in this kind of environment: the best way to look after yourself and not be a nuisance to others is to never assume right of way, paddle sensibly and sensitively around other water users. In some situations (particularly on narrower sections of the river or in any channels) traffic will stay to the right, as per inland waterways.

While yachts and boats seem the obvious hazards for paddleboarders, they’re usually skippered well – but it’s actually their mooring buoys and associated architecture that can cause the biggest issues to unwary paddleboarders. Especially if there’s a bit of tidal current, being swept onto a mooring buoy or into a pontoon can happen surprisingly quickly. Then there’s the danger of your leash getting caught up, which in extreme situations can prove fatal. This is why some paddlers opt for quick-release waist-leashes in tidal estuaries – but the best way to stay completely safe is to avoid the risk in the first place. So never to paddle too close to mooring buoys, solid objects or any potential hazard: stay at least a board length away, ideally two, that way you’re not in any danger of getting tangled up in anything.


Environmental Considerations

Before paddling any tidal river, check permissions and restrictions – some estuaries are under the control of a harbour or river authority who may well require you to buy a licence to paddle. There should be signage about, or if you’re unsure just ask other paddlers / water users. Estuaries are also important habitats for wildlife, so look out for protected areas, abide by any rules or regulations that are in place, and keep a respectful distance from birds and marine animals.

What Kit?

Of course you’ll need a board for paddleboarding on river estuaries and tidal rivers – it could be anything really, but for estuary touring we’d recommend our Voyager, Sport+ or Sport ranges – and a paddle. Next on the list is a Quick-Release Waist Belt. Safety-wise also consider a secondary flotation device such as the SUP Buoyancy Aid. And finally, in case of emergency carry a phone in a Waterproof Dry Pouch.

Happy Paddling…

As long as you know your tides and weather, and plan your route accordingly, estuary paddling can be some of the best SUP there is – so get out there and enjoy it!