will I sink or float 50N bouyancy aid

[alan_d]

Sam Goodchild's experiences on falling in the Southern Ocean during the Global Ocean Race are worth quoting.

Calmly, Goodchild prepared for an extended period in the water: “I was wearing full foulies and boots and mid-layer thermals and they filled up with water,” he explains. “Waves began breaking over my head and started pulling me down, so, slowly but surely, I stated taking them off; mid-layers, smock, everything down to my thermal top.” Shedding the extra weight came at a heavy price: “It started getting cold,” Goodchild confirms. “I had a knife in my smock pocket, so I cut the hood off my smock, which is bright yellow, and gave me something to wave. I ditched everything else – there was no point holding on to anything that wasn’t going to help me.”

The fact that he did this and survived does not mean that because he did this he survived. As has been mentioned several times before, saturated clothing (provided it is under the water) is of roughly neutral buoyancy and, particularly in the Southern Ocean, is helpful in retaining body heat.

 

[fishermantwo]

In my previous career I spent 14 years as navy aircrew and wore an inflatable life vest almost daily. These are different to all those inflatable 150nm jackets I see worn all the time here to satisfy local regulations to cross bars. Still yet to see one with proper crutch straps worn!

The military inflatable vests are higher rated, I thought they were 220 but they may well be 275. They are rated higher to support extra weight, weapons etc. The major difference is they have armpits in the vest that prevents them from rising up the body, they don't need crutch straps because they are properly designed and not built down to a price. The military inflatable will actually support a dressed man in its un inflated state simply because there is more material down lower in the water where its going to have more effect.
Buoyancy vests are rated at 50n. Some probably are but I would bet my left nut that the majority are well above that simply because they have more buoyancy lower in the water. Who has not floated about with their head and shoulders clear of the water with a vest. Add a wetsuit and its hard to stay in the water. It all boils down to how much material is in the buoyancy vest and how much of it is below the armpit. There are a choice of styles for various activities but the type one will be more than adequate as long as you have the correct size.
I wear a buoyancy vest to cross the bar.

 

[William_H]

as stated before its to keep your head out of the water but my 50n buoyancy aid has no problem keeping my 100 kilo frame wetsuited with a wakeboard strapped to both feet afloat,even laying backwards with your feet up to the surface your heads still out of the water.can even put your feet in the boots and do the laces up whilst floating.trying to swim on your front is a no no though.

Ah now you are talking wetsuit and a thick wetsuit will have a lot of buoyancy. In my experience comparable to 50N. Perhaps if it weren't for the struggle to get a wetsuit on this would be a better for keeping him warm both in spray and in the water. olewill

 

[CreakyDecks]

Most people actually have the same buoyancy at 100 feet as on the surface because people are mostly water and we don't compress well.

This isn't true. Most of our buoyancy comes from the air in our lungs and that is compressible. When my kids were younger I used to baffle them in the swimming pool on holiday by being able to lie down on the bottom of the pool. Try as they might they couldn't do it because of course the last thing they did before submerging was to take in a big breath, while I was sneakily breathing out as much as I could. Believe me, with hardly any air in your lungs the human body does NOT float! This has implications for life jacket requirements because if you were unfortunate enough to have just exhaled when you were knocked unconscious and over the side by your boom the only thing holding you up would be your life jacket.