‘What size PFD do I need?’
‘Do lifejackets have a weight limit?’
These are just two questions (of many) that regularly surface when kicking off conversations about getting marine enthusiasts into the best possible PFD for their adventures.
Whether you have a specific activity you’re looking to find a PFD for, or if you’re wondering what vest best suits your height and weight, we’ve lined up expert insights from the engineers here at Mustang Survival to help you confidently navigate your personal PFD selection and purchasing process.
The answers to the ‘best PFD’ questions might surprise you - and it’s all based on science. Come along for the ride as we explain buoyancy, and how choosing a PFD comes down to two simple questions.
What is buoyancy?
Buoyancy is the upward force of a body of water or fluid that gets applied to any object entering it, that opposes the weight of that object - whether fully or partially submerged. The amount of buoyancy applied to an object is dependent on how much water the object moves (or displaces) when it enters the water.
If the object moves less water than its weight, it’ll sink. If it moves more or an equal amount to its weight, it will float.
What’s interesting is what happens to, and with, the human body while in water. And, how the principles of buoyancy involve thinking beyond weight, and into a whole world of factors. Essentially—and in an oversimplified statement—bodies get lighter. A LOT lighter.
In fact, the United States Coast Guard has published on their Boating Safety website that ‘most adults only need 7 to 12 pounds of buoyancy (31 to 53 Newton) to keep their heads above water’. For context, the MIT70 inflatable PFD—one of our most minimal profile PFDs—offers 15.7 pounds of buoyancy (70 Newtons).
There is no ‘one equation’ that computes weight into in-water weight; factors like body composition, height, shape, weight distribution, and aspects of the physical body unique to each human being are too vast to reliably and consistently quantify it. Something as simple as someone inhaling can affect their body’s buoyancy (making them more buoyant as they fill their lungs, and less when they empty them).
A common misconception is that individuals with a higher body weight assume they need a PFD that offers the highest amount of buoyancy (the greatest number of pounds of support). When in actuality, a body’s weight on land doesn’t inform how much poundage you need. Its composition is what brings buoyancy into perspective: the leaner—the less body fat you have—the higher buoyancy you require.
When Mustang Survival engineers take to the drawing board to create a new PFD or optimize an existing one, beyond bringing the wearer to the surface of the water (and depending on the PFD, turn them onto their back), they’re engineering for angles; the angle of the wearer’s face to the water, and where the corner of the wearer’s mouth sits when they’re floating.
The goal is to get the head and mouth as high out of the water as possible. Which is what PFDs with higher buoyancy offer; more lift/upthrust (ie: displacing more water) to take the wearer further up and out of the water.
Here’s where it gets tricky: body weight and weight distribution *can* impact those angles they engineer for. It’s something that can’t be avoided (again, with the uniqueness of each body), yet should be noted when choosing the PFD best suited to you, and what you’re heading out to do.
Choosing the best PFD for you.
With a science-backed understanding of how buoyancy works, and knowing there are many choices you can make when it comes to your PFD selection, here are the top two questions to consider when narrowing down your search:
What are you doing?
Where are you going to be?
What activity are you doing?
Activity matters as there are PFDs that are best suited for certain kinds of adventures, and some that are certified for sure on or in specific watercraft. And, some PFDs offer incredible amounts of buoyancy, yet are cumbersome, limit mobility and take up a lot of space on deck. Understanding the demands of your activity can help you choose the best vest for your pursuits.
Where are you going to be?
Offshore in 6-foot high waves, or inshore enjoying the shoreline of a lake or inlet? Your environment plays a large role in choosing the best vest; with some certified for use inshore only. PFDs designed and engineered for offshore environments typically offer higher buoyancy to keep the wearer higher up out of the water in case of a delayed rescue (should one be required).
You may choose a higher amount of buoyancy because it feels safest. You may choose to go with the most minimal PFD that you can to optimize your comfort (while staying within the guidelines of your local transport or Coast Guard bodies). This guide to PFD Types can give you a sense of safety ratings by Type and environments they’re designed to perform in.
When it comes down to it, the best PFD is the one you wear.
With every PFD Mustang Survival engineers, we look to balance safety with comfort; offering the peace of mind that your PFD will keep you afloat, making products that can perform in the most grueling environments while staying out of the way, and having you nearly forget you’re wearing one.