Why Immersed CLO Is the True Measure of Polar Suit Performance

diego7475
Oct 14
3 min read

In polar survival, insulation isn’t just about what’s inside—it’s about how it performs when wet.

When it comes to immersion suits designed for polar environments, one metric stands above all others: CLO value, the measure of thermal insulation. But not all CLO is created equal. The real test of a suit’s protective capability lies in its immersed CLO—how well it insulates when submerged in freezing water.

At White Glacier, we design our suits to perform in the harshest conditions on Earth. That means engineering for real-world survival, not just lab benchmarks. Here’s why immersed CLO is the number that matters most.

What Is Immersed CLO?

CLO (short for “clothing insulation”) quantifies how well a material resists heat loss. In dry conditions, it’s a straightforward measure. But in polar immersion, the game changes.

Immersed CLO accounts for:

Compression under water pressure
Water saturation of insulation materials
Convective heat loss in turbulent seas

This adjusted value reflects the actual thermal protection a suit provides when submerged—offering a realistic estimate of survival time in cold water.

NRC Trials: A New Benchmark

Recent trials conducted by the National Research Council (NRC) confirm what our engineering has long predicted: White Glacier suits deliver 4–5× higher immersed insulation than many SOLAS-type immersion suits.

This dramatic performance gap is not just academic—it translates directly into extended survival time, greater comfort, and enhanced operational safety in polar emergencies.

Why Immersed CLO Is Essential

Many suits advertise high insulation values based on dry testing. But in polar emergencies, those numbers can be misleading. The moment a suit hits the water, its insulation is challenged by the environment. Materials compress, water infiltrates, and heat loss accelerates.

White Glacier’s suits are engineered to maintain high immersed CLO, ensuring:

Extended survival time in freezing water
Reduced risk of hypothermia
Improved comfort and mobility during rescue operations

Using the Hayes & Cohen (1987) survival time model, our suits demonstrate survival durations that far exceed industry standards—even in 2°C water.

Designing for Immersed Performance

At White Glacier, we prioritize immersed CLO in every aspect of suit design. From material selection to integrated features like the Splash Tent, our suits are built to preserve body heat in the most extreme conditions.

The Splash Tent, for example, creates a protective microclimate that reduces wind and wave exposure—further enhancing the effective immersed CLO by minimizing convective heat loss.

The Regulatory Shift Toward Realism

As Polar Code compliance evolves, regulators are increasingly emphasizing realistic testing conditions. Immersed CLO is becoming a central metric for evaluating suit performance, ensuring that survival claims are based on actual water immersion scenarios—not just dry lab tests.

Fleet safety managers, ship operators, and emergency response teams are now looking beyond traditional specs to understand how suits perform when it matters most.