What is a rip?
A rip current (often called a rip) is a narrow body of water moving out to sea. These pose a risk to swimmers as they can sweep people out to sea quickly.
How are rips formed?
As waves travel from deep to shallow water, they eventually break near the shoreline. As waves break, they generate currents that flow both offshore (away from the coast) and alongshore (along the coast). The larger the surf, the stronger the rip current.
How to identify a rip current
Look for these features to help you identify a rip:
- Calm patches in surf with waves breaking each side. Gaps between the waves. The calm gap may look safe to swim but a small patch of calm water in amongst surf or waves is often a rip current.
- A ripple pattern on the sand or small holes beneath your feet in the water.
- Discoloured or foamy water. Regions of deeper, darker water with less wave breaking activity between areas of white water; think of them as rivers of the sea. The discoloration is created by the current picking up sand in the water as it moves out to sea.
- Rocky Headlands and Rocky Groins. Rip currents are also common in areas with piers, jetties and anything else that sticks out from the beach that could catch a longshore current and cause it to start flowing away from shore.
If you’re unsure about conditions ask the nearest Lifeguard otherwise, stay out.
If you get caught in a rip
RELAX and float to conserve your energy.
Stay calm, relax and float. The rip current will not pull you under the water and is just taking you for a ride offshore.
Try to fight the urge to swim back to shore against the current; this will use up energy that you need to stay afloat before help arrives. Most people can float for a lot longer than they can swim!
RAISE your hand to signal for help.
Signal for help by putting your hand up to attract attention from lifeguards, surfers or someone on the beach who can get help.
RIDE the rip until it stops and you can swim back to shore or help arrives.
Remain floating until the current weakens. Many rips will circulate and bring you back into shallower waters closer to the shore where you may be able to stand.
When the current has subsided, and only if you are sure you can swim to the nearest point on the shore, should you attempt to swim to safety.
Types of rip currents
Permanent rips are stationary year round. As the intensity of the surf increases, so too does the intensity of the rip. Permanent rips often occur where there is a barrier to water movement along the beach such as headlands and rocks, or man-made barriers, such as wharves and drainage pipes. In many areas, permanent rips are given names relating to nearby landmarks or streets. Such identification can be invaluable when surf lifeguard teams answer emergency calls.
A permanent rip at Karekare beach.
Fixed rips are accompanied by a hole or gully on the ocean floor, with sand as its base. Once established, the fixed rip may last from several hours to many months. The length of time depends on the movement of sand. These rips are usually created when water from incoming surf increases (such as on a high tide) between the shore and offshore sandbars. The water then returns to sea through the path of least resistance, the lowest point in the sandbar system.
A fixed rip at North Piha.
Flash rips are temporary rips generated by increased volumes of water brought on to the shore. These rips can occur without warning, and subside rapidly. The nature of these rips means swimmers can be pulled out to sea quickly from areas of water that were safe only moments earlier.
Travelling rips move out to sea and along the beach. They are pushed by the prevailing direction of the waves and usually occur when the swell is moving strongly in one direction. Travelling rips moving along the beach can cause big problems for swimmers, often pulling large numbers offshore.
Unlike rip currents that are formed by wave energy, rip tides are caused by tidal action. Rip tides typically occur as water rushes through estuary and inlet entrances during tidal changes.