Myth: Rip currents pull you under water. In fact, rip currents carry people away from the shore. Rip currents are surface currents, not undertows. But while rip currents can move fast, they won’t take you far off shore. If you find yourself floating away from shore, try to relax, float, and wave for help.

Figure 14.16: Thermohaline currents are created by differences in density due to temperature (thermo) and salinity (haline). The blue arrows are deep currents and the red ones are surface currents.

The Role of Density Saltier water is more dense than less salty water; cold water is more dense than warm water. Denser water tends to sink, while less dense water tends to rise. Cold-water currents occur as the cold water at the poles sinks and slowly moves toward the equator.

Density currents in nature are exemplified by those currents that flow along the bottom of oceans or lakes. Such subaqueous currents occur because some of the water in an ocean or lake is colder or saltier or contains more suspended sediment and, thus, is denser than the surrounding waters.

Dangerous currents occur in many ocean and Great Lakes beach areas. Dangerous currents are dangerous because they can pull swimmers away from shore. Swimmers near structures are more likely to die. Dangerous currents can exceed 5 mph — faster than an Olympic swimmer can swim (2 mph and faster are considered dangerous).

Moving at speeds of up to eight feet per second, rip currents can move faster than an Olympic swimmer. Lifeguards rescue tens of thousands of people from rip currents in the U.S. every year, but it is estimated that 100 people are killed by rip currents annually. If caught in a rip current, don’t fight it!

1. Signs that a rip current may be present. A break in the incoming wave pattern. A channel of churning, choppy water.
2. If caught in a rip current. Stay calm. Don’t fight the current.
3. Helping someone else. Many people have died while trying to rescue others caught in rip currents. Don’t become a victim yourself.

Rip currents are generally no wider than about 15 m (16.4 yards), so you only need to swim a short distance to try and get out of the current. Once out of it, you should be able to stand up and make your way back to shore in the areas where you can see breaking waves.

In physical oceanography, undertow is the under-current that is moving offshore when waves are approaching the shore. An undertow occurs everywhere underneath shore-approaching waves, whereas rip currents are localized narrow offshore currents occurring at certain locations along the coast.

Rip current speeds are typically 2 to 3 feet per second and extend about 200 feet offshore. RIPTIDES A riptide (or rip tide) is a powerful current caused by the tide pulling water through an inlet along a barrier beach. Riptides also occur in constricted areas in bays and lagoons where there are no waves.

This may be due to any combination of fear, panic, exhaustion, or lack of swimming skills. Rip currents are the greatest surf zone hazard to all beachgoers. They can sweep even the strongest swimmer out to sea. Rip currents are particularly dangerous for weak and non-swimmers.

Trying to swim against a rip current will only use up your energy; energy you need to survive and escape the rip current. Do NOT try to swim directly into to shore. Swim along the shoreline until you escape the current’s pull. When free from the pull of the current, swim at an angle away from the current toward shore.

Those are the primary reasons boaters wearing life jackets sometimes drown. Either the boater is unable to free him- or herself from some type of entrapment, is unconscious or otherwise unable to keep his/her face out of the water, or eventually drowns from numerous mouth immersions over a prolonged period of time.

Life Jackets and the Law Under California law, every child under 13 years of age on a moving recreational vessel of any length must wear a Coast Guard-approved life jacket in serviceable condition and of a type and size appropriate for the conditions and the activity.

Type III PFDs are suitable for most paddlers where there is a chance for quick rescue. They offer freedom of movement and comfort for continuous wear. These PFDs are designed so wearers can put themselves in a face-up position, but they may have to tilt their head back to avoid being face down in water.

Wearer may have to tilt head back to avoid going face-down. Will not hold the face of an unconscious wearer clear of the water. In rough water, a wearer’s face may often be covered by waves. Not for extended survival in rough water.

Type III jackets typically feature a front entry and buckle, or buckle-and-zipper closure. The catch with Type III jackets is that they are designed for conscious wearers with an imminent chance of rescue; a Type III jacket is not guaranteed to turn an unconscious wearer face up in the water.

Here are the best life jackets, life vests, and PFDs:

• Best life jacket overall: Astral BlueJacket Kayak Life Vest.
• Best for fishing: NRS Chinook Fishing PFD.
• Best for small children: O’Neill Wake USCG Vest.
• Best inflatable vest: Onyx M-24 Manual Inflatable Vest.
• Best affordable vest: Stearns Adult Classic Series Vest.