Afterdrop: forty minutes of shivering I should have expected
The sea on Sunday was 10.5 °C by my thermometer, flat, grey and almost windless, which is exactly the kind of morning that invites you to stay in longer than you should. I stayed in nine minutes. In November, in skins, that is at the upper end of what I allow myself, and I felt fine getting out: cold hands, pink skin, clear head, the usual pleased-with-myself glow.
Afterdrop is the thing nobody warns you about properly. When you swim in cold water the body shuts the blood supply to the skin and limbs to protect the core, and the core temperature holds while the outer layers get very cold. When you get out and the blood starts returning to those cold layers, it comes back to the core cooler, and your core temperature keeps falling for twenty or thirty minutes after the swim is over. The worst of the cold comes when you are already dressed and think it is finished.
On Sunday I made it worse by being slow. I chatted at the water’s edge in a towel for perhaps five minutes, then dressed in the wrong order, trousers before top, and stood on wet shingle in bare feet looking for socks. By the time I was in the car the shivering had started; by the time I was home, twenty minutes later, it was violent enough that I could not hold a mug steady and my speech was slow. I sat under a blanket with a hot water bottle on my stomach and drank sweet tea, and it was forty minutes before it eased. It was not dangerous, I think, but it was closer to the line than I have been and it frightened me a little.
The routine since then, written on a card in the swim bag and followed without discussion:
- Out of the water at the planned time, not a stroke more.
- Hat on first, before anything else, while still wet.
- Dry the top half roughly, warm layers on top immediately, then deal with the bottom half.
- Feet on a mat, never on stone; thick socks and boots before walking anywhere.
- No hot shower for an hour, since it pulls blood to the skin and worsens the drop; hot drink and movement instead.
- Walk for ten minutes before driving.
Nine minutes at 10.5 °C is now eight, and in December it will be six. The glow at the water’s edge is not information; the shivering half an hour later is.