Rip Current and backwash examples

Saw this whilst exploring some coast I’m not as familiar with as I’d like. Great example of a rip current and a strong backwash.

The biggest danger here are actually wave surges up the beach and the backwash. Dog walkers or walkers not paying attention, getting knocked over fully dressed and rolling down the beach! If you look at the conditions, it’s unlikely anyone would pop in for a swim…and if you did, the 4-6 foot shorebreak, breaking in 6 inches of water would be your main concern. The rip currents only go out just past the breaking waves…so are actually fairly tame…in isolation.

Rip currents are bodies of water that find themselves above sea level. In this example, a wave having flown up the beach. Once above sea level, the laws of gravity will dictate that this body of water returns to sea level. The body of water in question will naturally find the path of least resistance. On the video (although you can’t see it), there is a stream on the far right, flowing into the sea. This stream gauges a channel out of the beach and creates a natural flow of water into the sea… so you find a rip current here. The slopes either side of the stream encourage the water to flow down hill and the sea water joins the stream and flows out nice and easy. In the middle of the frame you see another rip current. The beach slopes into a slight valley (in the middle of the beach) and the water again, flows down the side of this ‘valley’ and out. The more water that does this, the more this valley has sand carried out with the current and the deeper this ‘valley’ becomes.

*There are actually 3 rip currents just in frame, one on the near side…but I didn’t want to make this article too confusing. You wouldn’t normally get 3 rip currents so close together but there is such a mass of water flowing up the beach with the swell and the beach is so steep, that the water returns back out to sea at high speed…if the waves were breaking further out, some of this energy would disperse naturally on the way in.

Spotting a rip current at Perranuthnoe Beach

In this blog post we look at a straight forward rip current at Perranuthnoe Beach, in west Cornwall. Generally, with no swell Perranuthnoe can be a very safe beach to swim at. However, add a few waves and it can be quite the opposite. They do have lifeguards for the 6 peak weeks of the summer. As you can see in this example. As well as rip on the west side of the beach, there was also a diagonal rip on the east side.

Now in this example, the rip runs from around waist height in the water, right out just past the breaking waves. It runs near the headland. Rips will often run along headlands, harbour walls, rocky surfaces, as the smooth rock offers less resistance and the water flowing back out to ‘sea level’ will always follow the path of least resistance.

What this video does highlight very well and this is generally the case…is that you rarely find rip currents where there is a consistent breaking wave. This is because the depth of the sand creates the waves…whereas rip currents tend to dredge water off the bottom as the water flows out and this creates a deeper channel. This is why waves don’t break in rips. In some instances, they will break further out and then peter out as the wave travels over the deeper section of rip current. This video demonstrates this very well.

Rip Current awareness / Identification

So I popped across to Praa Sands today, as there was a decent swell, with the aim of getting footage of a rip current. Today was a lovely January day, just after a storm…so plenty of swell around.

Now this isn’t your text book rip current and that’s what I like about it. Most rip diagrams show you a perfectly formed rip, running at 90 degrees to the beach. More often than not, rips don’t follow this pattern. They come in all kinds of weird and wonderful shapes and can change shape and strength, depending on the conditions, tidal movement etc.

In this instance, you have a deep(er) ‘trough’ and diagonal rip current which leads onto a shallower bank, where some waves are breaking. This wouldn’t be the worst rip in the world for swimmers, as it would simply push you down the beach (from right to left), onto a shallower bank…where you should be able to get in fairly easily. *It would be more of a problem for children and poor swimmers, as it would carry them out of their depth fairly quickly and induce panic. It would also carry you into the bigger waves, which again can cause panic and issues for less experienced swimmers.

In this example, had the tide been 15-20m higher, this rip current would be much stronger and would lead it’s victims out just past the breaking waves, into deeper water. It’s also worth bearing in mind that if the tide was 20-30m further out (towards low tide), this rip current would simply be dry sand and wouldn’t cause any problems at all. Be aware that rip and their position do change with the tide. The position of rip current on a beach between high and low tide for example, can be very different.