As you see from the pic below, auto-inflate absolutely. Specifically Crewsavers
out of the UK - their top hydrostatic model.
This is a picture from an Ocean Youth Trust voyage where I was mate aboard a 60' OYT ketch
. That week, we had a bunch of 11-13 mentally challenged kids
with us in February. Ocean temperature was 2 degrees celsius.
had really begun to come together as a crew by then. They understood when the captain
called out a command, they needed to respond quickly and with an action.
We were coming alongside at the Isle of Wight and the stern needed to come in. I had initially taken the stern line to more of a midships cleat to leverage the stern in, but the stern was creeping towards the dock
, so Paul called, "Let's move that stern line to a stern cleat, please!"
It happened in a split-second. I took the line off the dockside cleat to walk it towards the stern - and one of the kids grabbed the onboard end and gave a quick, sharp pull in response to Paul's command.
Suddenly, I was in the sea, in my full foulies and sea boots. The auto-inflate immediately exploded and just as suddenly, I was bobbing on the surface. Of course, on surfacing, I had gasped loudly with the coldness of the sea and all of the kids began screaming and crying.
I swam over to the ladder, stood up on the dock
(shivering uncontrollably), but I wanted to stop the kids' fright, so I clowned around by taking off my sea boot and dumping out all the water
"It's okay, kids! I'm okay!" - which made the kids laugh.
Then, of course, properly secured the stern line one-boot-on-and-one-boot-off, and walked straight for a hot shower
If I hadn't had the auto-inflate LV on, those sea boots would have taken me straight to the bottom.