By the time we found their 23-foot center console, the husband and wife were huddled together against the port gunwale and unable to reach the VHF radio. The boat was aground on a remote outer island of Virginia’s Eastern Shore, just north of the entrance to the Chesapeake Bay. The flight mechanic hoisted me down to the beach, and I walked to their Boston Whaler and stepped aboard. “Is everyone alright?”

They couldn’t talk. In fact, both were barely able to shiver. Sliding down the bad side of hypothermia, the couple was wearing soaking wet shorts and light jackets. The two of them would not have made it until dawn without a rescue.

When they left the marina for a few hours of fishing, it was 78 and sunny. They had planned to be back well before nightfall; long before the temperatures dropped into the 40s and the rain started.

We got them to the hospital where they made a full recovery. They were grateful. But I couldn’t help but whisper in the husband’s ear as I left the emergency room, “Next time, pack a sweater and some rain gear. We could have dropped you at your car.”

It doesn’t matter what the weather is like when you leave the dock. You have to prepare for an overnighter — a cold and miserable one. Being prepared for the wet and cold can mean the difference between an uncomfortable delay or a deadly one, and this time of year (late September through October) is when things are the most dangerous. Beautiful days start turning into frigid nights, so your safety and survival gear should include (I’m serious) clothes. The warm stuff. Here is what I suggest.

Layers — Synthetics Only

“Cotton kills” is something we used to say a lot in teaching survival. Cotton holds moisture, and moisture ruins insulation. It’s the insulation that keeps you warm.

Pack two layers of synthetic tops. The long-john style is good for a base layer, and thicker sweaters or sweatshirts work well for a mid layer. Pants aren’t as important, but I recommend you invest in keeping your bottom half warm as well.

You simply cannot go wrong keeping a heavy synthetic jacket aboard. If you live in a place with a real winter, you likely have four old ones in a closet somewhere anyway. Dedicate one to your vessel to be ready for a long, unplanned night outside.

Hats, Socks And Gloves

You may have heard the saying, “You lose 80 percent of your body heat through your head.” That’s a complete myth that I’ll explore next week, but you should still keep your head warm. Pack a synthetic skull cap and find some gloves and thick socks while you are at it. You are going to need your dexterity to work the tiny buttons on your phone or VHF radio if you end up needing to call for help. Gloves may be why you can. Also, you can live with cold feet, but why suffer?

Rain Gear

No spare clothing kit is complete without a top layer of rain gear. You can go high-dollar if you want, but for emergency purposes, expensive foulies aren’t any more effective than a poncho fashioned out of a plastic tarp. No kidding, my spare rain gear includes two large, plastic, lawn-and-leaf bags. I won’t win a fashion award in them, but they do the job. The only downside is that they make a terrible passive-signaling device. If you are committed, purchase the good stuff with reflective tape for the complete package.

Permanent Spares

You should handle spare gear as lifesaving equipment. It may one day be needed to help you survive, so treat it accordingly. Make rain and cold-weather gear a permanent addition and store it on your vessel. Don’t make it something you have to remember each time you go out.

How you store this gear is another matter, but any stowage method that keeps it clean and dry will work. On vessels where space is at a premium (that’s all of them, right?), you can pack cold and wet weather clothes using vacuum sealers. Compression (space-saver) bags work well, too. I like dry bags. I fit everything I mentioned above (X-large sizes, thanks) easily into one 10-liter dry bag.

No one plans on it (though you should), but boats run aground, lose power for a variety of reasons and things get wrapped in props. These are all, for the most part, minor inconveniences. In warmer months, unplanned extended day trips lead to boredom or, at worst, mild hunger pains while you wait for a tow to arrive.

But this time of year — when nice days turn into freezing nights — these otherwise annoying problems can lead to a white-knuckled fight for your life, all for want of a damned sweater. You’ll feel awfully silly shivering under a heated blanket in the emergency room or worse — and run the very real risk of having your rescuer call you out for being silly.