John_newNo one ever plans to need a life jacket. But when you’re in trouble on the water, that’s the wrong time to look for one, says John Drengenberg, consumer safety director for UL. That’s because they don’t work unless you’re wearing them, he says.

More than 500 people drown every year in incidents in which a life jacket could have helped — and 80 to 85 percent of the people who drowned were not wearing a life jacket.

Here Drengenberg answers a few questions to inflate our knowledge about these life-saving devices.

Dear John: How do I pick out a life jacket?

Look for the UL Mark, which means the life jacket meets the requirements set by the US Coast Guard and UL for use of personal floatation devices (PFDs). Also, look at the weight restriction on the jacket. Life jackets are tested based on weight restrictions for many of the tests. Make sure the jacket is appropriate for your weight and size.

Choose the right type of jacket for your activity. There are five types. Type 1 jackets are for use farthest off shore (and therefore farthest from help) — out in the open ocean or in the middle of the Great Lakes, for example. Type 2 life jackets are for waters closer to shore when there aren't a lot of people around (and your chances of being rescued quickly aren't great). Type 3 life jackets are for recreation in waters close to shore, when there are plenty of boaters or swimmers in the area and there’s a good opportunity for a quick rescue. A type 4 device is the throwable ring you can toss to someone in distress. Type 5 are specialized for white water rafting and board sailing.

If you’re not sure what you need, go to a local marine supply store and talk to someone who works there.

Related: A Day at the Lake? Avoid an Ocean of Trouble

Dear John: How should my life jacket fit? How can I tell if it’s going to do what it’s supposed to do?

Make sure it’s snug enough so it won’t come off if you jump in the water. How? Take the "touchdown" test. Raise both arms (or have your child raise hers) straight up in a “touchdown” signal. If the life jacket hits your chin or ears, it may be too big or the straps may be too loose. Also, check to make sure the bindings are good and the jacket is nice and tight.

When you wear it for the first time, check it in the shallow water. Try to float face down — Type 1 and 2 life jackets should turn you over so your nose and mouth are out of the water, in case you’re unconscious. To test the other types, try relaxing your body and tilting your head back. The jacket should keep your chin above water, and you should be able to breathe.

Every year, before boating season, check it for rips and holes. If you see those, that’s a sign the material could be compromised when you get into the water. With children, check the size every year. Children grow and it might now be too small or make them uncomfortable, and they may take it off. If your child is growing and gaining weight, the old life jacket may not be good enough to keep them buoyant in an emergency.

Dear John: How many life jackets should I have on my boat, and where should I keep them?

Most states require as many life jackets in the boat as you have passengers. It’s always good to wear them whenever you’re in a boat, but at least know where they are and how to get them on quickly.

As for where to keep them, somewhere easily accessible is the best explanation. It’s hard to make a rule because all boats are so different.

Store life jackets out of the sun — don’t store it on the seat of your boat when you’re not using the boat. Long-term sun exposure can damage the material. If you see damage, get a new one.

Related: Boating Safety: Could You Pass the U.S. Coast Guard Test ?

Dear John: Do water wings or inflatable tubes protect my kids as well as a life jacket in the pool?

Many people who have pools in their yard believe those inflatable water wings you put on a kid’s arm or inflatable tubes or donuts will protect your children, but they won’t. They deflate very quickly if they rub a rough spot on the side of the pool and are not a substitute for a life jacket.

Related: Life-Saving Water Safety Tips: Make Your Pool a Drowning-Free Zone

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Angela is a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide. Prior to joining SafeBee, she was the features editor for at The Boston Globe, overseeing health, travel, entertainment, business and lifestyle coverage. Before moving to features, she was the news and homepage editor, covering stories such as the Boston Marathon bombing, Red Sox World Series victories, presidential elections, a papal inauguration, and more. Her favorite safety tip: Clean your phone! The average cell phone has 18 times more germs than the toilet handle in a men’s restroom.