Being knocked off a ship is one of the most disorienting and terrifying experiences you can have.
German sailor Arne Murke had this happen when he was knocked off a sailboat in 9 foot waves, and without a life preserver. Fortunately, Murke had the wherewithal to employ a trusted life-saving trick used by Navy SEALs that starts by taking off your pants, and was rescued off New Zealand after over three hours in the water.
The method uses your pants to assist with flotation to stay on the surface and conserve your energy. And unlike a dead man float where your face is in the water, this tactic allows you to rest with your face up so rescuers can more easily find you.
Here’s how to perform this tried-and-true “drown proofing” technique, which is taught to troops from all the military branches.
Step 1: Take off your pants. While you tread water or lie on your back, tie a knot in the ends of the pant legs. The US Navy recommends you tie both pant legs together and tight enough to trap air, as seen in a 2015 video. Oh, remember to zip up the fly.
Step 2: Inflate. Put the waist opening over your shoulder, then in one motion raise the open waist high over your head to scoop in air and then slam it into the water. Close the waist underneath the water to hold in the air.
A US Army soldier sits upright after inflating his pants and putting his head through the legs.
(US Army photo by Visual Information Specialist Pascal Demeuldre)
Step 2.5: If your air pocket isn’t filled enough, repeat the last step. Or you can try to fill the pants by going under water and breathing air into the open waist.
Step 3: Put your head through the inflated pant legs and hold the waist closed and under water. Wait for help and stay calm. If and when the pants deflate, just repeat the steps.
These moves are fairly straightforward, but it’s hard to get the pants to inflate by swinging them over your head. It may take a few tries. Best to practice this in a pool first.
Watch the US Navy video here:Navy Skills for Life – Water Survival Training – Clothing Inflation
This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.