My post timed out. . . .
there is a big difference between a life jacket and a personal flotation device (known as a PFD)
A life jacket is a life an automatic life saving floatations devise that does not require the wearer to be able to swim to prevent drowning, a PFD is a floatation aid devise, designed only to aid the wearers floatation whilst swimming or otherwise in the water.
A life jacket can either be an inflatable one (now days these ones usually self inflate when they detect water) or a non inflatable one, a life jacket is what it says, it a life jacket and to meet the current regulations of a life jacket it must keep wearer afloat with their head up out of the water un aided and even if they are unconscious, examples of a life jacket:
(note how they give buoyancy around the back of your neck, this will turn you over so you float on your back with your face out of the water)
These are PFD jackets used mainly on jet skies, kayaks, sailing boats, dinghys, water skiers and by people fishing off piers and river banks etc the idea with the PFD's is that they aid your body's own buoyancy, you can wear them in the water and still have full movement ie. . . you can swim with them on and get in and out of boats etc easily (you can't do so with a traditional life jacket and an automatic self inflating life jacket for such activities is out the question as it will self inflate as soon as it detects water thus needing to be re packet and a new gas inflated cartridge fitted) I also like PFD jackets as they give your chest and back protection I've been thrown from a RIB boats a few times and on one occasion whilst beaching in rough sea the boat turned sideways and flipped landing upside down on top of me with the outboard slamming into my chest without a PFD jacket on my ribs would have been smashed to pieces, a PFD jacket has 2 inch thick buoyancy foam in all of the front and back. You can get basic no pocket, no frills PFD' and delux ones such as Delta and Ranger, but make sure it is at least 50N buoyancy that's the current CE standard and make sure it has at least one waist belt as well as the zip as if you trying to lift someone out of water by their PFD it won't rip open and slip off with a waist belt
my advise is to stay away from what you've seen and posted above.
Avoid this style with no waist belt:
these look good and tempting but no waist belt
Look for these type:
Delta ranger and nookie I use and posted in the forum:
https://www.thebushcraftforum.uk/threads/delta-ranger-pfd-life-jacket.4987/
https://www.thebushcraftforum.uk/threads/nookie-explorer-2-pfd.6062/#post-64528
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