You are six times more likely to die in a boating accident without a life jacket than with one.
They are the most talked about safety item for boating as well as working or playing in, around, or on the water. They are your first and last line of defense against drowning… and they are the easiest to forget.
In this first installment of “The Required Safety Items Explained,” we will discuss the different kinds of personal flotation devices, from life jackets to life rings, what “pounds of buoyancy” means, why it matters, and when you are required to bring and wear a life jacket.
Types of Personal Flotation Devices
Let’s get the basics out of the way first, then we’ll discuss what pounds of buoyancy means and the specifics, and why not give away a prize at the end?
All personal flotation devices are divided into five types based on their use, from offshore jackets to wearable cold weather immersion suits. Types I, II, III and V each have three versions: inherently buoyant, inflatable, and a hybrid inflatable that has some buoyancy when non inflated. There are two main versions of a Type IV: ring buoy and cushion.
Type I – An “offshore” life jacket with a minimum of 22 pounds of buoyancy for a foam jacket and 33.7 pounds for an inflatable jacket. The hybrid versions have a minimum of 15.5 pounds when deflated up and 32 pounds when fully inflated. A bigger life jacket designed to turn an unconscious person face-up, it provides greater buoyancy for potentially longer rescues. The inherently buoyant version of this PFD is required for commercial vessels and all vessels carrying passengers for hire in case the ship must be abandoned.
Type II – A “near-shore” vest with a minimum of 15.5 pounds of buoyancy for a foam jacket and 33 pounds for an inflatable jacket. The hybrid versions have a minimum of 10 pounds when deflated and 22 pounds when fully inflated. They are also designed to turn an unconscious person face-up but do not have as much buoyancy as an “offshore” life jacket.
Type III – A flotation aid with a minimum of 15.5 pounds of buoyancy for a foam jacket and 22 pounds for an inflatable jacket. The hybrid versions have a minimum of 10 pounds when deflated and 22 pounds when fully inflated. These are NOT designed to turn an unconscious person face up. This is a standard vest designed to be more comfortable for water sports, such as water skiing or tubing.
Type IV – A throw-able device, such as a ring buoy (life ring) or boat cushion, with minimum 16.5 pounds of buoyancy for ring buoys and 18 pounds for boat cushions. They are designed to be grasped, NOT worn. They are designed to be used when someone accidentally falls overboard without a life jacket or needs extra help floating. Throw it NEAR the person, not at them, this is not a ring toss game.
Type V – A special use device; it must be used in accordance with the directions and requirements on the approval label. This type covers a broad range of devices, such as a cold water immersion suit or a “float coat.” Hybrid inflatables must have 7.5 pounds of buoyancy when deflated and 22.5 pounds of buoyancy when inflated. Buoyant foam devices must have between 15.5 and 22.5 pounds of buoyancy, and inflatable devices must have between 22 and 34.8 pounds of buoyancy when fully inflated. A Type V will have special instructions for use and wear.
Inherently buoyant personal flotation devices (PFDs) require very little maintenance, come in adult and children’s sizes, and can be used by almost anyone. Inflatable PFDs contain a backup oral inflation tube, come in adult sizes only, are recommended for swimmers only and require regular user checks to maintain. They are not recommended for water sports or activities that involve frequent water entry, such as water skiing, as they could inflate when you do not need nor want them to inflate. To inflate they will have either an automatic inflation device or a manual release connected to a CO2 cylinder. Inflatable PFDs are also less reliable than inherently buoyant PFDs because of the maintenance required and because many people do not perform the required maintenance. Hybrid PFDs are made with a combination of buoyant material and an inflatable bladder, come in adult and children’s sizes and require regular maintenance due to the inflation mechanism. Hybrids are generally more comfortable than inherently buoyant PFDs but are also not recommended for water sports as they could inflate when not needed.
Pounds of Buoyancy of Lifejackets
How does a life jacket with 15.5 pounds of buoyancy hold up a 200-pound person? What does “pounds of buoyancy” actually mean?
One pound of buoyancy is the amount of buoyancy required to keep one pound of dense rock or metal, like lead, afloat. If a life jacket is required to have 15.5 pounds of buoyancy, that means it can keep 15.5 pounds of dense rock or metal afloat.
Now let’s see how that translates for a 200-pound person. The simple explanation is you weigh less in the water than on land, with only a small fraction of your body weight unsupported by the water. Think about it: when you try to lift someone up in a pool, it’s a lot easier than on land, isn’t it?
The longer version (bear with me for a minute, there’s a cool dog sporting a sweet jacket at the end): Your body is made up of water, fat, and protein. The majority of the body is water, on average about 65%, which means it’s the same thing you are floating in and does not require any support to stay afloat.
Now think about your body fat percentage. The average male has 16-20% body fat and the average female has 20-25%. Even the leanest bodybuilders have body fat, though likely in the 3-5% range (which is why they sink more easily). Pure fat has less density than water, about 0.9 kilograms per liter for fat compared to 1 kilogram per liter for water. Simply put, fat floats.
All that remains is the body proteins, which for the average person makes up about 10-20% of their total body weight.
Back to the 200-pound person. Let’s stick with some averages from above and say this person is a male with 20% body fat and 65% of his body is water.
Total weight of his body that is water (65%): 200 * 0.65 = 130 pounds.
Total weight of body that is fat (20%): 200 * 0.2 = 40 pounds.
Leftover weight (body proteins): 130 + 40 = 170 ; 200 – 170 = 30 pounds.
With this average 200 pound male, 130 pounds is water and 40 pounds is fat. The fat itself is buoyant and the water weight has neutral buoyancy, meaning it neither sinks nor floats. The total of 170 pounds requires no assistance, or extra buoyant force (a life jacket), to remain afloat.
We are now left with 30 pounds of body weight that is proteins. The remaining 30 pounds still has volume and therefore has some buoyancy.
For body proteins, this density averages 11.18 pounds per US gallon (weight for a given volume).
Total volume = 30 pounds / 11.68 pounds per US gallon = 2.68 gallons.
That 30 pounds of body weight will displace, or take up the same amount of space as 2.68 gallons of water.
One US gallon of fresh water weighs 8.34 pounds; 2.68 gallons of water weighs 22.35 pounds. (2.68 * 8.34 = 22.35)
Last bit of technical stuff: Water exerts a buoyant force equal to the weight of the volume which is displaced (thanks, Archimedes), or, water pushes up on the object with a force equal to the weight of the water that was moved. Push down on a partially inflated beach ball in the ocean, then inflate it all the way and push down again. More water is being displaced when the ball is fully inflated than only partially inflated, so the water pushes back more when the beach ball is fully inflated.
That 30 pounds of body weight in the water is being pushed up by 22.35 pounds of water, leaving 30 – 22.35 = 7.65 pounds left of unsupported body weight.
Our 200-pound man actually weighs much, much less in water, and only 7.65 pounds is unsupported! (And don’t forget that buoyant fat actually pulls him up a bit too!)
That life jacket with 15.5 pounds of buoyancy is more than enough to keep that 7.65 pounds of unsupported body weight afloat. That extra buoyancy means if you fall in with all of your clothes on and some stuff in your pockets, you should still have more than enough buoyant force to keep you and your phone afloat. Your phone probably will not work after that, but you’ll have plenty of time to think about what phone you are getting next while you bob around effortlessly in the water as that life jacket keeps you safely afloat.
Salt water has a greater density than fresh water, so the amount of unsupported weight is less in salt water than in fresh water. With that said, here’s the tricky question: why does an offshore jacket have to have more pounds of buoyancy than a near-shore vest?
Half of the answer is the salt water itself, and the other half is the fact that it is likely to take longer to rescue a person who is farther offshore than someone who is close to shore. Simply put, you will become dehydrated. The salinity in a person’s body is lower than the salinity in the ocean, and based on the principle of osmosis, the water in a person’s body will attempt to equalize the salinity levels. You will have less water in your body, increasing your body density and requiring a greater buoyant force to keep you afloat. You are also likely to become more tired, thereby reducing your ability to keep yourself afloat. This extra buoyant force is designed to help you save energy and keep you afloat until help arrives. I promise we are done with the science now, and the dog is just a little farther down the page.
When do you need a life jacket?
Every single time you get on the water.
Whenever you go out on the water, regardless of the size of your boat, canoe, kayak, paddleboard, or whatever you are using, you must bring a life jacket. If you’re operating in waters where the US Coast Guard has jurisdiction, you must have one life jacket for every person on the boat. If anyone on the boat is under the age of 13, they must actually wear an appropriately fitted life jacket at all times (i.e, for a child, it must be a child size life jacket designed to fit a child’s body). All life jackets must be Coast Guard approved. If your boat is 16 feet long or greater, you must have a Type IV (throw-able flotation device- see above) device. And no, throwing an extra life jacket does not count.
All states have similar laws for life jacket use and wear, so double check with your local authorities to ensure you have the proper equipment.
So Why? And Which life jacket Should You Bring?
According to the Coast Guard, someone is injured or killed in a boating accident every 2.5 hours, and you are six (6) times more likely to die from drowning in a boating accident without a life jacket than you are with one. Nine out of 10 drownings occur in inland waters, most within a few feet of safety. Most of the victims owned PFD, but they died without them because they never put them on. It also helps to wear them properly…
The above statistics are the reason there are so many different campaigns out there for drowning prevention and wearing personal flotation devices:
There are several reasons to bring a life jacket besides simply being required to by law. It’s fun to bob around in the water without having to swim, and if you are looking for a little relaxation, just lay back and let the life jacket do the work for you. They are not expensive, and even fashionable! You can buy almost any color or print you want these days.
Life jackets don’t have to be expensive, either. You can buy a Coast Guard approved, adult Type II life jacket from a local sporting goods store for less than $10. (Google it; if you cannot find one, send me an email and I’ll send you an autographed postcard of me wearing the aforementioned life jacket and the link to where you can buy one of your own. Sorry, I don’t autograph life jackets. Yet.) You can outfit an entire family of four with life jackets, including the dog, for less than the cost of taking them to the movies with popcorn and soda. And the dog would not be allowed in the theater, so it’s even more of a win!
It is up to you what type of personal flotation device you wear when you go out on the water, just make sure it is appropriate for what you are going to do, for your size, and body type. For example, don’t wear a Type I to go waterskiing in Florida, but do bring a Type I for that offshore fishing expedition. Wear the Type III for waterskiing in Florida, but if for some reason you are going water skiing in Alaska you may need a Type V. A Type II or Type III is well suited for a near shore fishing trip. If you are working near the water, such as a dock worker, a Type III is best suited as it will not restrict your movement while still providing the safety necessary. In that situation, you may also want to consider using an inflatable life jacket as they will provide the greatest range of movement. Also, keep in mind, if you have more muscle mass, you will need a larger size life jacket with more pounds of buoyancy. All you body-builders out there may want to opt for an inflatable or a hybrid as they allow greater movement and more buoyancy.
Life jackets save lives, pure and simple. That is their one true purpose. Do yourself, your family, your friends, and everyone around you a favor. Bring a life jacket. Forgetting them is also the most bone-headed reason to be sent back to the dock by the Coast Guard, and they will send you back.