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Yankee Hill Beach
This beach and most other North Shore beaches on Prince Edward Island, like Rustico and Cavendish, are known for their strong rip currents. It is important to heed the posted warnings and exercise due diligence when swimming and wading along these shores.
Rip Currents
A rip current is a strong horizontal, surface flow of water returning seaward from near the shore. It is often called a “rip tide” or “undertow”, though the occurrence is not related to tides, they do not pull people under the water—they pull people away from shore. Although rip currents would exist even without the tides, tides can make an existing rip much more dangerous, especially low tide. Typical flow is at 0.5 meters per second (1-2 feet per second), and can be as fast as 2.5 meters per second (8 feet per second) – faster than an Olympic swimmer can sprint! Rip currents can move to different locations on a beach break, up to 100 meters (300 feet) a day. They can occur at any beach with breaking waves, including the world’s oceans, seas, and large lakes.
Identifying Rip Currents
Look for any of these clues:
1. A channel of churning, choppy water;
2. An area having a notable difference in water color;
3. A line of foam, seaweed, or debris moving steadily seaward;
4. A break in the incoming wave pattern.
5. The water line is lower on the shore near a rip current
None, one, or more of the above clues may indicate the presence of rip currents. Polarized sunglasses make it easier to see the rip current clues provided above.
Dangers
Rip currents can be extremely dangerous, dragging swimmers away from the beach and leading to death by drowning when they attempt to fight the current and become exhausted. Although uncommon, a person standing waist deep in water can be dragged out into deeper waters by a rip current.
If caught in a rip current, DON’T FIGHT THE CURRENT. Swim or float out of the current in a direction following (parallel) the shoreline (Figures 1 & 2). Only when out of the current should you attempt to swim towards shore.
Rip currents cause approximately 100 deaths annually in the United States, more than all other natural hazards except heat and floods. Over 80% of rescues by surf beach lifeguards are due to rip currents totaling 18,000 lifeguard rescues a year.
Causes and Occurrence
The mechanics of rip current development are complex and involve interactions between waves and currents, waves and water levels, waves and the shape of the near-shore bottom (bathymetry), as well as wave-wave interaction. Rip currents can occur along any coastline that features breaking waves.
As waves travel from deep to shallow water, they will break near the shoreline. When waves break strongly in some locations and weakly in others, this can cause circulation cells which are seen as rip currents: narrow, fast-moving belts of water traveling offshore (Figure 3-5). When wind and waves push water towards the shore, the previous backwash is often pushed sideways by the oncoming waves. This water streams along the shoreline until it finds an exit back to the sea. The resulting rip current is usually narrow and located in a trench between sandbars, under piers or along jetties. The current is actually strongest at the surface and can dampen incoming waves, leading to the illusion of a particularly calm area that can lure some swimmers in.
Rip currents are stronger when the surf is rough, such as during high onshore winds, or when a strong hurricane is far offshore, or when the tide is low. Rip currents are very unsteady and may increase in strength within a short time frame (a few minutes) because of larger incoming wave groups or current instabilities. Rip currents can be very narrow or extend in widths to hundreds of meters in the alongshore direction. The seaward pull of rip currents also varies: sometimes it ends just beyond the line of breaking waves, but sometimes they continue to push hundreds of meters offshore.
Undertow
Undertow, an often misunderstood term, refers to the backwash of a wave along the sandy bottom. After a wave breaks and runs up the beach face, some of the water percolates into the sand, but much more of it flows back down the beach face creating a thin layer of offshore-moving water with a relatively high velocity. This backwash can trip small children and carry them seaward. However, the next incoming wave causes higher landward velocities, pushing them back up on the beach. While potentially dangerous, undertow is not a rip current and does not pull you under water or out to sea.
To claim this Earthcache:
1. Take and post a picture of you and your GPSr at the posted coordinates, with the distant pilings in the background, and e-mail me the answers to the following questions:
2. What is at least one visible, physical factor on or near this beach that could contribute to local rip currents?
3. Can you see a rip during your visit? Describe the color difference and what causes this difference.
Do NOT post your answers on your log, encrypted or otherwise.
DO NOT LOG AS A FIND UNTIL YOU HAVE A PICTURE READY TO POST AT THE TIME OF LOGGING A FIND FOR THIS EC. Logs with no photo of the actual cacher logging the find or failure to answer required questions through e-mail will result in a log deletion without notice. Exceptions will be considered if you contact me first.
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