When Is it Safe to Swim in the Sea?

This question is asked time and time again. Whilst we can't be held responsible for your decision to enter the water, we can certainly help you to make your own risk assessment.  Join us on our Introduction to Open Water Swimming Course which gives you an indepth guide on what to look out for and how to make your swim in the sea safer. 

Below are some things to look out for before you enter the water:

1. Does the Beach have a Lifeguard?

If it is does then there will be flags displayed. There are three common flags which you need to know about and are displayed in the Poster below. There may also be a windsock which will show you the direction the wind is blowing.

2. What do the Waves Look Like?

Spend a couple of minutes looking at the waves and assess them. Are they soft and consistent, breaking gradually as they reach the shore? If so these waves are called Spilling Waves. Or are they breaking on the shore with a lot more force? Then they could be a Dumping Wave. Perhaps they break and then pull the sand and pebbles back with them, these are called Surging Waves. Generally speaking avoid the Dumping waves and Surging waves as these can knock you over as you try to get into the sea. The surging wave is a strong wave and can pull you out to sea with it. 

3. The Power of The Wind.

Wind is caused by Temperature. Gases move from high pressure areas to low pressure areas. The bigger the difference between the pressures the faster the air will move from the high to low pressure. That rush of air is the wind we experience.

Wind will affect your swim. So spend some time checking the weather forecasts. Although nothing is better than actually standing on the beach to make your assessment. If the sea looks rough it makes sense to leave it for another day. Remember the sun can be shining and creating the feeling of a lovely day, but the wind can still be strong. The wind speed will always take precedence over the amount of sunshine there is, when determining whether to swim or not.

There are several apps available and websites, where you can put in your postcode and it will give you an hour by hour prediction of wind speed. One of these is Wind Observation Map - Britain (xcweather.co.uk) Put in the postcode and you will get a table of the wind speeds for the day. Look at this in conjunction with the Beaufort Scale.

The Beaufort Scale

Ideally you do not want to be swimming in anything more than Beaufort 4 which is around 13mph to 18mph. Above this and you are in quite choppy water. Look also at the direction of the wind. A south wind means the wind is originating in the South, so it is blowing towards the north. If you are in our usual swimming spot of Lee on Solent then a south wind will be blowing off the sea towards the shore and pushing the waves into shore. A north wind on the other hand will mean calmer waters as it is blowing from land onto the sea. 

4. The Tide

If you are swimming in an area you haven't swam in before, for example you if are on holiday, always check the tide tables. You do not want to get cut off by the tides and risk being in a dangerous predicament. 

But whilst tides can be unpredictable, they do follow a regular pattern. Tides are very long waves that move across the oceans. They are caused by gravitational forces exerted on the earth by the moon, and to a lesser extent, the sun. When the highest point in the wave or crest reaches a coast the coast experiences a high tide. when the lowest point or the trough reaches a coast the coast experiences a low tide. 

Spring tides have a greater variance than Neap tides and this usually means they have a very low tide and a very high tide. Here at Lee on Solent, when there is a Spring tide, we have to wade out a lot further at low tide for swimming, than if it was a Neap tide. Neaps and Springs follow the pattern of the moon. The first and third quarter moon is a Neap tide and a Full moon and a New moon are Spring tides.

Tides also affect the way the water flows. However for a period of time after high tide, the water will remain fairly static and this is referred to as slack water. This in some parts of the world can be for only a few minutes, whilst in others it is very much longer. In Lee on Solent it is around one hour. 

When there is a Spring tide, the current flows are stronger and faster. So if swimming on a low Spring tide and you have waded out a fair way for a swim, remember to move back in to shore with the tide, otherwise you may get caught up in a fast flowing current and taken out further to sea.

Tide tables for the UK can be found here

5.  Storms

You are probably thinking to yourself that you wouldn't be so stupid as to start swimming in a storm. But make sure you don't get caught out! Always check the weather forecast before reaching the beach. Even after a storm, danger lurks in the sea in the form of debris. Fence panels, shrubbery and even large tree branches could have ended up in the sea. 

6. General safety Advice

Always swim adjacent to the shore. Never venture too far away from the shore line. In a bay or cove there is some shelter from currents but if you venture too far out then you could be taken further out to sea and not be able to swim against the flow to get back in. 

Take a tow float with you so you can be spotted easily from shore. Carry your mobile phone in a waterproof pouch. The RNLI sell these. Dial 999 in an emergency and ask for the Coastguard.

7. Increase your knowledge

Sign up to our Introduction to Open Water Swimming course and gain a more indepth knowledge of the safe ways of swimming.

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