The summer has come and there are already many tourists who are enjoying the beaches of Terracina to take the first “tan” and a bath. The sea is quite friendly but, if you want to enjoy its benevolence, you have to treat it with great respect, because it also can hide some snares, with great danger to the health and safety of people. One of the most dangerous snares is undoubtedly the current known as “rip tide”.
It is a specific kind of water current which can occur near beaches with breaking waves. A rip is a strong, localized, and narrow current of water which moves directly away from the shore, cutting through the lines of breaking waves like a river running out to sea, and is strongest near the surface of the water. Rip currents can be hazardous to people in the water. Swimmers who are caught in a rip and who do not understand what is going on, and who may not have the necessary water skills, may panic, or exhaust themselves by trying to swim directly against the flow of water. Because of these factors, rips are the leading cause of rescues by lifeguards at beaches.
A rip current forms because wind and breaking waves push surface water towards the land, and this causes a slight rise in the water level along the shore. This excess water will tend to flow back to the open water via the route of least resistance. When there is a local area which is slightly deeper, or a break in an offshore sand bar or reef, this can allow water to flow offshore more easily, and this will initiate a rip current through that gap.
Water that has been pushed up near the beach flows along the shore towards the outgoing rip as “feeder currents”, and then the excess water flows out at a right angle to the beach, in a tight current called the “neck” of the rip. The “neck” is where the flow is most rapid. When the water in the rip current reaches outside of the lines of breaking waves, the flow disperses sideways, loses power, and dissipates in what is known as the “head” of the rip.
Rip currents have a characteristic appearance, and, with some experience, they can be visually identified from the shore before entering the water. This is useful to lifeguards, swimmers, surfers, boaters, divers and other water users, who may need to avoid a rip, or in some cases make use of the current flow. Rip currents often look a bit like a road or a river running straight out to sea, and are easiest to notice and identify when the zone of breaking waves is viewed from a high vantage point. The following are some characteristics that can be used to visually identify a rip:
- A noticeable break in the pattern of the waves — the water often looks flat at the rip, in contrast to the lines of breaking waves on either side of the rip.
- A “river” of foam — the surface of the rip sometimes looks foamy, because the current is carrying foam from the surf out to open water.
- Different color — the rip may differ in color from the surrounding water; it is often more opaque, cloudier, or muddier, and so, depending on the angle of the sun, the rip may show as darker or lighter than the surrounding water.
- It is sometimes possible to see that foam or floating debris on the surface of the rip is moving out, away from the shore. In contrast, in the surrounding areas of breaking waves, floating objects are being pushed towards the shore.
These characteristics are helpful in learning to recognize and understand the nature of rip currents so that a person can recognize the presence of rips before entering the water.
Rip currents typically flow at about 0.5 metres per second (1–2 feet per second), but they can be as fast as 2.5 metres per second (8 feet per second), which is faster than any human can swim. However, most rip currents are fairly narrow, and even the widest rip currents are not very wide; swimmers can easily exit the rip by swimming at a right angle to the flow, parallel to the beach. Swimmers who are unaware of this fact may exhaust themselves trying unsuccessfully to swim against the flow. The flow of the current also fades out completely at the head of the rip, outside the zone of the breaking waves, so there is a definite limit to how far the swimmer will be taken out to sea by the flow of a rip current.
In a rip current, death by drowning occurs when a person has limited water skills and panics, or when a swimmer persists in trying to swim to shore against a strong rip current, thus eventually becoming exhausted and unable to stay afloat.
A person caught in a rip current may notice that he or she is moving away from the shore quite rapidly. It is often not possible to swim directly back to shore against a rip current, so this is not recommended. Contrary to popular misunderstanding, a rip does not pull a swimmer under the water, it simply carries the swimmer away from the shore in a narrow band of moving water. The rip is like a moving treadmill, which the swimmer can get out of by swimming across the current, parallel to the shore, in either direction, until out of the rip current, which is usually not very wide. Once out of the rip, swimming back to shore is relatively easy in areas where waves are breaking and where floating objects and swimmers are being pushed towards the shore.
As an alternative, swimmers who are caught in a strong rip can relax and go with the flow (either floating or treading water) until the current dissipates beyond the surf line, and then they can signal for help, or swim back through the surf diagonally away from the rip and towards the shore.
It is necessary for coastal swimmers to understand the danger of rip currents, to learn how to recognize them and how to deal with them, and if possible to swim in only those areas where lifeguards are on duty.