Hope this may save a life
Rip Current Study - Created by the Foundación de Salvavidas y Protección Costera
Prepared for Parque Nacional de Costa Rica
By Donald R. Melton and Anita H. Myketuk - 1976
Translated by Rowena A. Washburn and Richard A. Washburn
Our study of rip currents has culminated with a general public education leaflet designed to teach recognition and safety. We believe that every school teacher in Costa Rica should read it and then explain it to their students. All newspapers should publish it immediately prior to school vacation periods.
We personally swam under the most dangerous circumstances and read some of the best scientific literature available to write this leaflet. After nearly five months of observations we believe many more lives will be lost unless this summary is will understood.
Our wording is deliberately non-technical for the purpose of offering a quick and easy conceptualization of rip currents. Everyone should learn how to see them, feel them, escape of make a rescue, and especially how to avoid them. We believe that every ocean swimmer should know that a rip current normally travels between four and six miles per hour and that a very good swimmer moves only three miles per hour.
Any ocean beach that experiences wave action will have rip currents. Because so many lives have been lost circa Playa Manuel Antonio, we hope our information will be appreciated by all Costa Ricans.
We are grateful to Senior Alvaraldo Ugalde, Commissioner on Natural Resources, who asked us to make this study. We are also grateful to Rowena H. Washburn and her father, Richard A. Washbrun for translating our study into the spanish language. Senior Louis Mendez, Jefe del Parque National has been magnanimous with his cooperation. We sincerely appreciate these and many other persons who have helped us with this study for their genuine concern for the life and safety of people who will be swimming on some of the most beautiful beaches on earth.
Rip currents can be described as having three parts: feeder current, neck, and head. The feeder current moves parallel to the shoreline, staying between the area of wave breakage and the beach. Swimmers feel a lateral pull along the beach, often on the opposite side form which waves approach. This lateral pull continues until the current breaks and turns outward into the sea.
When swimmers feel a pull toward the sea they have most likely entered into the outward moving part of a rip current called the neck. These rip current necks can be either wide or narrow, depending on the steepness of the beach. Usually a steeper beach has a narrower and stronger neck, while conversely, a gently sloping beach has a wider and weaker neck. The current of the neck continues outward beyond the breaker line before it finally looses energy and dissipates. When a swimmer no longer feels an outward pull, then the swimmer has entered into the final phase which is called the rip current head. The distance from the shoreline where a rip current dissipates into a head is determined by two factors: the volume of water being returned to the sea; plus the width and depth of the neck channel carrying the outward bound current. A more complete discussion will follow pertaining to wave theory feeding ever present rip currents but first some advice to swimmers caught in any of the three components of a rip current.
Swimmers and especially non-swimmers should learn to recognize a rip current by both feel and sight. We have just described how each of the three component parts of a rip current feels. It is still easier to see a rip current. Waves rise and become steeper as the depth of the ocean floor decreases. Waves collapse or break when the water becomes too shallow. When certain parts of a wave do not rise as soon, nor does it break as far out as the rest of the wave then there is probably a rip current present. Since rip currents are channels of water flowing seaward either carving or finding a depression on the sea floor, the water depth is actually greater than at other places along the beach. This deeper water prevents or retards wave breakage. Ironically, this appearance sometimes makes a dangerous area appear safe.
There is another way to sight a rip current. Usually the water within a rip current is brownish in color. This is because the laterally moving feeder current picks up or moves sand toward and into the rip current neck. In other words, churning of sand turns the water a brownish color so a clear view of the entire rip current is present. Beyond the breakers where the outward flowing current looses its energy, the sand is spread about by incoming waves thus taking on a mushrooming shaper of a rip current head. Bathers should always be able to recognize the feel, shaper, and color of a rip current.
Although rip currents are always present as a means of recirculating shore water back into the sea, they are sometimes more dangerous then at other times. They become increasingly dangerous whenever wind blows, especially from the seaward direction; or when abnormal amounts of water are brought ashore because of some distant storm. Beach users should be cautious about entering the water under these conditions.
Three other circumstances that signal danger are: extreme ends of beaches, rocky areas, and where land water empties into the sea. Extreme ends of the beach often have obstacles that prevent the alongshore current to continue in any direction except outward, thus there are sometimes rip currents in these areas. More than fifteen persons have lost their lives at the southernmost extreme of Playa Espadilla near Manuel Antonio National Park because of currents forced outward.
The next circumstance, the rocky areas, should be avoided by swimmers. Not only are these places potential rip current areas, but waves can slam a swimmer into a rock causing injury. Often rocks are hidden by swells and then catch swimmers by surprise when they try to swim over them. Rocky areas area also where spiney sea urchins are usually found which may cause further injury.
The last of our rip current areas to be discussed is where land water empties into the sea. Rivers and streams often cause or contribute to rip currents. Even where rivers or streams are temporarily dry, they may have cut sub-litoral drainage channels into the sea floor making a natural place for the alongshore current to break outward as a rip current.
From the above description swimmers should know the feel, sight, probably location and probable time of rip current. For the weak or nonswimmer, rip currents should be avoided. For the confident swimmer, they should know where and when to be on guard for their fellow beach users. Here are some tips on how to escape a rip current, plus how to use a rip current to better advantage of a rescue.
Foremost: Don't Panic. Panic wastes energy and causes irrational behavior. You will be safe if you take time to calm yourself and think about what you are going to do. If you can float, an nearly everyone can float, you are safe. If you did nothing but float you would eventually end up behind the breakers in the relatively calm rip current head. We do not recommend merely floating. Swim parallel to shore. Swim toward the shore at about a 45 degree angle away from the rip current and you will soon find yourself safely on the beach.
Do not retreat from a rip current by swimming directly toward shore unless your feet can provide traction on the sea floor. A direct route out of a rip current is like swimming up a river. Not only do you have the current pushing against you, but there is often turbulence in the current as it clashes with incoming waves. Swimming parallel to the rip current offers advantage of relatively calm water with waves pushing the swimmer shoreward a few feet at a time.
A swimmer attempting to rescue a person caught in a rip current should use the current to his advantage. It is much less tiring and much faster to ride with the current to where a victim awaits. It is interesting to note that surfers ride rip currents seaward and then paddle laterally into their surfing zones.
A final word of advice. Don not swim if you have consumed alcoholic beverages or if you have eaten within the previous hour.