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Difference between rip currents and rip tides

Kristin Joson

(July 4, 2014) The local newspapers, television and radio have been very supportive in helping us get our beach and water safety messages out to the public.

This time of the year you will hear a lot about the dangers of rip currents in the local news. This often creates questions about the differences between a rip current and a rip tide and what makes them so dangerous.

You will see stories on local and national news about rip currents. Although they are often mistakenly referred to as “rip tides,” they are in fact a current. A current is simply a volume of water moving from one location to another. In contrast, tides are caused by the gravitational pull of the moon and sun and occur about every 12 hours.

What makes a rip current dangerous is that it moves water away from beach and out to sea, where north or south currents just move water along the beach. As water flows away from the beach, in the rip, anything or anyone in that water will also be pulled steadily away from shore and into deeper water. This can be a scary experience. It is one thing to be moved along the coast with a current but being pulled away from shore is often not desired.

The action of the rip not only accounts for how unsuspecting bathers and people never intending to go out further than their waist are pulled into water that is over their heads.  It also is responsible for creating the telltale signs that identify a rip current to the trained eye. As waves break and stir up the sandy bottom and create foam this discolored water and foam are carried away from the shore clearly marking the location of a rip current.

While the mechanics of a rip current are easily understood, they still remain the greatest surf zone hazard for anyone enjoying water activities at any beach and account for 95 percent of all water related rescues in Ocean City. Rip currents are such a well-known natural hazard that the National Weather Service has identified them as the third leading cause of weather related death.

If you question the seriousness of this threat then just take a moment to realize that not all states could even contribute to this statistic because not all states have ocean beaches. So being the third leading cause of weather related death in the United States is quite significant.

To understand how to escape a rip current it is important to understand what causes rip currents. Rip currents occur when water that comes into the beach by wave action and wind, needs to make it’s way back out. Because a sand bar runs the length of Ocean City, water that has come over the sand bar needs to make its way back out. Because wave action continues to bring water over the sandbar, the water has difficulty going out against the incoming flow.

Water will take the path of least resistance and find a lower spot along the sandbar to become the natural path for the flow of the water. As more water comes across the sandbar the volume in the trough (water trapped between the beach and sandbar) increases and this additional volume of water causes an increasingly greater volume of water to flow through this path. As water flows along this path it will move sand and creates a deep underwater channel from the shoreline through the sandbar. As waves break near the beach they cause a change in bathometry (the contour of the ocean bottom), which causes a constant change in the sandbar and thus rip current locations and severity are constantly changing.

Rips can open up at any given time, sometimes referred to as “Flash Rips.” Just last week I was out swimming and I could see little rips opening up where just minutes before there weren’t any in the area where I was swimming. It was a rough choppy day and the sandbar was constantly shifting causing rip currents to open and flow away from the shore.

Another factor that has an influence on the frequency and severity of rip current activity is water depth, which is directly related to changing tides. This is why rip current risk may be reported as moderate at 1 p.m. and become high at 4 p.m. The Ocean City Beach Patrol provides rip current assessments to NOAA three times each day.

We have also worked directly with scientists to understand rip currents and how to better forecast and predict them. In a few weeks a world famous scientist who has studied rip currents around the world, Dr. Rob Brander, from University of New South Wales, Australia, will visit the mid-Atlantic area. He has indicated that he’d very much like to meet with the OCBP, as he remembers being impressed with what our patrol is doing, especially related to education and outreach work regarding beach and ocean safety.

Rip currents do not pull a person under water as a lot of people believe. It is the deep channel cut into the sandbar that gives the impression that a swimmer maybe pulled down. In reality what is happening is a non-swimmer who intended to remain only in waste deep water is being moved by the rip current into increasingly deeper water channel.

Since they cannot swim, they try to stand on the bottom and as they move away from the shore the water becomes over their head and they are no longer able to keep their head above water. Therefore, a person watching from the beach may think that what they believe they are seeing is a person being pulled under. When in fact, it is a non-swimmer who does not have the ability to keep their head above water. If this occurs while the beach patrol is on duty the lifeguard will simply assist the person back to safety.

However if this occurs while lifeguards are not on duty, the outcome may be deadly.

You may believe that only non-swimmers drown as a result of rip currents while in reality many rip current drowning victims had moderate to good swimming ability. This brings up the question, why would a person who knows how to swim, drown? The answer is simple. Panic, fatigue and lack of ocean awareness all contribute to the outcome.

A rip current is very much like a treadmill in the ocean. As water is flowing away from the beach, a swimmer attempting to swim straight in will make little or no progress against this outgoing current or “ocean treadmill.”

Since a rip current may flow faster than an Olympic swimmer can swim, swimming against this current only causes a person in this situation to become fatigued while getting no closer to the beach. Eventually they become so fatigued that they are no longer able to keep their head above water and once they slip below the water’s surface and are no longer able to get air, they become unconscious and only have moments before they become a statistic.

If you realize this can happen to even a swimmer then it isn’t hard to understand how suddenly a non-swimmer can be pulled from standing unaware in waist deep water with a crash of a wave set, to losing their footing and becoming an actively drowning victim who will quickly submerge, making a rescue nearly impossible.

In contrast a swimmer or someone with a flotation device can easily escape the grip of the rip. By nature, a typical rip current is not very wide usually 20 yards at most which means that a person who is being pulled out can be out of the rip after a few swimming strokes. Also once the rip current flows through the cut in the sandbar the pull disperses and the current no longer continues to pull you away from shore.

With these facts in mind if you find yourself being pulled away from shore, do not panic simply swim parallel (to the side) to shore (get off the “ocean treadmill” in the same manner you would get off the treadmill at the gym by simply moving to the side) and once you no longer feel the pull of the rip, swim back into shore.

If you feel you are unable to swim across the rip relax, let it take you out to the sandbar and then swim back to shore. Whatever you do, never abandon a flotation device and always signal the lifeguard if you want their assistance.  In most cases they will already be on their way to assist you back to safety. Even our lifeguards will not attempt to swim straight in against a rip current. They use their knowledge of the ocean to swim parallel to the beach until they are out of the rip current and then make their way back into safety with a victim in tow.

If you can remember the word RIP then you can remember what to do to save your life, R = Relax and do not panic, I = I need help (wave your arm), P= Swim Parallel (to the side) to return to safety.

For additional information about rip currents and other water safety topics visit  www.ococean.com/ocbp and follow the safety button. You can always approach any of our friendly lifeguards and ask them to talk to you about current conditions and information about rip currents.

Kristin Josonhttp://oceancitymd.gov/oc/departments/emergency-services/beach-patrol/
Kristin Joson has been working with the Ocean City Beach Patrol for 14 years. She is the Public Education Coordinator where her main responsibility is to work with public to fulfill the first part of the OCBP mission which is Education. The OCBP mission consists of 3 components Education, Prevention, and Intervention. By educating the public about beach safety, we believe there will be fewer instances where an intervention will be necessary. In the offseason, she is an Learning Resource Teacher in Charles County where she is the Testing Coordinator and the Gifted Resource Teacher for Berry Elementary School . The OCBP consists of over 200 men and women dedicated to ocean rescue and maintaining a safe and orderly environment on Ocean City’s beach. The Surf Rescue Technicians guard the beach seven days a week from 10 a.m. – 5:30 p.m. Always introduce yourself to the lifeguard on your beach, they are more than happy to answer any questions you may have.

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