What Size Inflatable Lifejacket Do I Need?

(Why Bigger Isn’t Always Better)

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When you’re heading offshore, chasing wind, tide, or horizon, the last thing you want is doubt about your safety kit. Yet one of the most common questions we hear is surprisingly simple: how much buoyancy should my lifejacket have?

It’s an important question, and there’s a huge number of lifejackets available across the industry, making lifejacket comparison tricky - even within some brands, it isn't clear! When looking at 150N, 170N, and 275N ratings, it’s an easy assumption that bigger numbers mean better protection. But out on the water, performance isn’t defined by a label; it’s defined by what happens when you hit the water.

The numbers don’t tell the full story. Let's dig in.

What Do 150N, 170N, and 275N Lifejackets Actually Mean?

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Lifejacket buoyancy is measured in Newtons (N), which refers to the amount of lift the jacket provides in the water.

As a general guide:

150N lifejackets are designed for general offshore and coastal use.
170N lifejackets offer slightly more buoyancy, and are often chosen when wearing heavier clothing or kit.
275N lifejacekts are intended for extreme conditions or when carrying significant weight such as tools, gear, and foul weather layers.

On paper, it sounds straightforward: more buoyancy equals more safety, but these ratings only tell part of the story. They don’t measure how effectively a lifejacket keeps your airway clear if you’re in the water, and that’s what really matters.

Why Bigger Isn’t Always Better

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We don’t need to tell you how sailing isn’t a static activity! You’re trimming sails, moving across the deck, and reacting to conditions as they develop. A lifejacket that’s bulky or restrictive can get in the way, and if it’s uncomfortable, you’re less likely to wear it properly, or at all. If you're not wearing it properly, then it can't do it's job.

More importantly, simply adding buoyancy doesn’t guarantee better performance in the water. In some cases, excess buoyancy can actually lead to less stable positioning, especially if it’s not distributed effectively.

The crucial question here isn’t how much lift does it have to keep me afloat?

Far more important is how well is it going to keep me breathing?

The Metric That Actually Matters: Mouth Freeboard

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If there’s one measurement that defines lifejacket performance, it’s mouth freeboard – the distance between the waterline and the corner of your mouth. That’s because the higher your mouth sits above the water, the easier it is to breathe, the less water you’re likely to inhale in waves, and the better your chances of staying conscious and conserving energy.

This is especially critical in rough conditions or if you’re unconscious. In either of these situations, you don’t want to be just floating – you want your airway protected. That’s why you’ve chosen a lifejacket over a buoyancy aid - you want to ensure you're face up in the water.

This is where traditional buoyancy ratings fall short, because they don’t tell you how high your airway will actually sit.

A Different Approach: The TeamO Offshore Hi-Lift

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The Offshore Hi-Lift takes a completely different approach to flotation. Rather than simply increasing buoyancy, it redistributes it, shifting lift from areas that sit above the waterline to where it actually makes a difference. The result is a dramatic increase in mouth freeboard.

In fact, the Hi-Lift keeps your mouth up to 60% higher above the water compared to other leading lifejackets.

That’s not a marginal gain – it’s a fundamental shift in performance. And what’s even more striking is that the Hi-Lift achieves this with a 150N rating, yet outperforms traditional 275N lifejackets where it matters most: keeping your airway clear.

This isn’t just a theory; it’s been recognised at the highest level. The Offshore Hi-Lift was awarded both the Personal Equipment category winner, and the Overall winner at the DAME Design Awards 2024.

These awards are judged by industry experts who understand exactly what good design looks like, and more importantly, what real-world performance demands.

Read more about our DAME Design Awards win here.

When Do You Actually Need More Buoyancy?

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There’s still absolutely a place for higher buoyancy lifejackets, but it just comes down to how you sail - or if you're taking part in a different watersport altogether.

If you’re regularly wearing heavy foul weather gear, carrying tools, or operating in demanding offshore conditions, stepping up to 170N or 275N can make sense. In those situations, the extra lift helps counterbalance the additional weight you’re carrying.

But for many sailors, especially those moving actively on deck, layering dynamically, or prioritising comfort over long periods, more buoyancy isn’t always the advantage it seems. In these cases, how that buoyancy is delivered becomes far more important than the number itself.

Design, Fit, and Freedom to Move

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It goes without saying that a lifejacket only works if you’re wearing it, are wearing it properly, and that it is properly maintained. That means:

A close, secure fit
Freedom of movement on deck
Balanced weight distribution
Regular servicing is completed by an ISO approved facility

All our lifejackets are designed with this in mind, combining high-performance flotation with a low-profile, ergonomic fit. With the exception of the Micro (our smallest, lightest lifejacket, designed for inshore sailing) our range includes BackTow Technology, which enhances safety during recovery by orienting the body in a way that supports safer retrieval from the water.

Because safety doesn’t stop at inflation – it continues through every stage of the rescue.

How to Choose the Right Lifejacket

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There’s no one-size-fits-all approach - what suits you might not be right for another member of your crew. When choosing your lifejacket, think about how and where you sail:

Coastal cruising vs offshore passages
What you typically wear on deck
The conditions you expect to face
How much movement your sailing demands

If your priority is maximum buoyancy for heavy gear, a 275N may be the right choice.

But if you’re looking for performance, comfort, and a lifejacket that actively improves your position in the water, it’s worth looking beyond the number.

Rethinking Safety at Sea

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Out on the water, confidence comes from knowing your kit works – not just in theory, but in practice. Buoyancy ratings are a great starting point, but they don’t tell you how a lifejacket will perform when it matters most.

That’s why the future of lifejacket design isn’t about making them bigger. It’s about making them smarter. Because in the end, safety isn’t measured in Newtons – it’s measured in how well you can breathe, stay afloat, and get back on board.

Still not clear which one is right for you before you buy? No problems, we're happy to answer your questions! Send your email to info@teamomarine.com or call us on +44 (0)1489 776000.