By the Chase Leavitt service team · Portland & Ellsworth, ME · Updated November 2026

The 1-10-1 rule

If you fall into cold water (anything below about 60°F — which is most of New England most of the year), three things happen on three separate clocks:

• 1 minute. Cold-shock response. Involuntary gasping. Hyperventilation. Inability to control breath.
• 10 minutes. Of meaningful muscle function. After that, your hands and arms stop doing what your brain tells them to.
• 1 hour. Until hypothermia becomes life-threatening. Some people last longer, some less.

That’s the framework. The first minute is the deadliest, not the last hour. Most cold-water deaths happen in the first three minutes — not from hypothermia, but from drowning during cold-shock response.

The first minute (cold-shock)

Cold-shock is the involuntary physiological reaction to sudden immersion in cold water. The body responds with:

• Sudden inhalation gasp (the most dangerous response — if your face is in the water, you inhale water)
• Hyperventilation lasting 1–3 minutes
• Spike in heart rate and blood pressure
• Inability to control breathing

The most important thing to do in the first minute: keep your face out of the water and don’t try to swim. Tread water. Wait for the gasping to subside. Then assess.

This is also why an immersion suit’s hood seal matters so much. A hood that doesn’t seal puts cold water on your face, which triggers the cold-shock response even if your body is protected.

The next ten minutes (muscle function)

Once cold-shock subsides, you have approximately ten minutes of useful muscle function. Use it.

Priorities, in order:

• Get on top of something — a raft, debris, the overturned boat. Reduce immersion.
• Activate signaling devices — EPIRB, PLB, AIS beacon, flares. Do this before your hands stop working.
• Get any other crew accounted for and grouped together.
• If you can self-rescue, do it now. After ten minutes, you can’t.

The first hour (hypothermia)

Hypothermia sets in over the first hour for most adults in 50°F water. The progression:

• Mild: shivering, confusion, fumbling. Onset 10–60 minutes.
• Moderate: shivering stops, lethargy, slurred speech. Onset 1–2 hours.
• Severe: unconsciousness, weak pulse. Survival without rescue beyond 2 hours becomes very unlikely.

An immersion suit dramatically extends this clock. A properly fitted, sealed suit gives you a working margin of 4–6 hours in 50°F water before severe hypothermia. That’s the difference between waiting for a 30-minute helicopter response and dying before they arrive.

What an immersion suit actually buys you

The immersion suit is not a magic talisman. It’s an insulating layer that buys you time. Specifically:

• It defeats cold-shock by keeping your skin out of the water.
• It maintains your body’s core temperature longer.
• It provides positive flotation (especially with the bladder inflated).
• It makes you visible (the orange shell + retroreflective tape).

What it doesn’t do: keep you dry indefinitely. Water finds its way in through the zipper, the hood, the wrist seals. Crews in suits in 50°F water still get hypothermic — just much slower. The point is the slow.

Self-rescue strategies

If you’re in the water and a raft is available:

• Get to the raft inside the first ten minutes.
• Boarding from the water is exhausting. Don’t try to climb up the side; use the boarding ladder or the entry point at the canopy.
• Once aboard, pump out water, set the sea anchor, and shelter from wind.

If you’re in the water and no raft is available:

• Don’t swim. Conserve energy.
• Adopt the HELP position — knees to chest, arms wrapped around legs. This minimizes heat loss.
• If you’re with other people, huddle together facing inward. The HUDDLE position.

Rewarming after rescue

The biggest risk after a rescue is rewarming shock. Don’t:

• Plunge a hypothermic person into hot water.
• Give alcohol — it dilates blood vessels and can cause a fatal blood-pressure drop.
• Rub the limbs.

Do:

• Get them out of wet clothes and into warm dry clothing or a sleeping bag.
• Apply heat to the core (chest, neck, head, groin) — not the limbs.
• Give warm sweet liquids if they’re conscious and able to swallow.
• Get them to a hospital. Severe hypothermia is a medical emergency.