Safety inflation.

[johnphilip]

My Kru Sport Pro lifejacket that I have had for perhaps 10 years has to be retired, the cylinder and firing mechanism has worn a hole through the fabric, (at least it shows I wear it.)
Looking to replace it my observation is that lifejackets have succumbed to the elf and safety habit of increasing protection because it "must" be better. Lifejackets used commonly to be 150N buoyancy, next 175N, now my new Kru is 195N.
Surely the only part of an inflated lifejacket that is giving you lift is that which is underwater. Unless the 150N jacket was becoming fully submerged an increase in size has negligable extra benefit. Why then the creeping increase, the height of the body in the water is going to be much more effected by having the jacket snugly fitted with a tight crotch strap than the size of the baloon waving in the breeze.

 

[pvb]

I'd imagine the trend is consumer-driven; buyers thinking that more buoyancy is better, without considering the practicalities.

 

[Resolution]

Average customer getting fatter? Or does fat float?

 

[Mark-1]

My Kru Sport Pro lifejacket that I have had for perhaps 10 years has to be retired, the cylinder and firing mechanism has worn a hole through the fabric, (at least it shows I wear it.)
Looking to replace it my observation is that lifejackets have succumbed to the elf and safety habit of increasing protection because it "must" be better. Lifejackets used commonly to be 150N buoyancy, next 175N, now my new Kru is 195N.
Surely the only part of an inflated lifejacket that is giving you lift is that which is underwater. Unless the 150N jacket was becoming fully submerged an increase in size has negligable extra benefit. Why then the creeping increase, the height of the body in the water is going to be much more effected by having the jacket snugly fitted with a tight crotch strap than the size of the baloon waving in the breeze.

A while back a magazine did a story that suggested that air trapped in oilies caused people to float face down. Maybe more buoyancy is a response to that issue. Either way you make a good point.

 

[Seajet]

I used my 175N Kru for real a few years ago when I managed to capsize my tender alongside the boat on the mooring; even that was very cumbersome indeed, not much chance of swimming even backstroke and made getting back aboard that much harder - I have some Crewsaver 250N LJ's too, god knows what they'd be like.

 

[pvb]

I have some Crewsaver 250N LJ's too, god knows what they'd be like.

Bibendum!

 

[DownWest]

A while back a magazine did a story that suggested that air trapped in oilies caused people to float face down. Maybe more buoyancy is a response to that issue. Either way you make a good point.

Along with keeping ones head out of the water.
Having had to swim quite a long way on my back in cold and choppy water with an old tech mouth only puff up, I view LJs as a last resort while hoping that the Helio finds you (quick..). Once the LJ is inflated, your options are limited to waiting in most situations. In my case, I knew that it was unlikely that help would arrive, so I did the best I could and managed to make the shore.
If I knew I was going over, I would wear a wet suit. Keeps you slightly warm and able. But I never sail expecting to fall in ... and drysuites I find a bit claustraphobic.

As Annie Hill said: Don't fall over. Day time, some chance. Night time, your dead.

 

[Seajet]

Maybe worth a couple of reminders here of things people tend to forget or not be trained;

If caught out without a lifejacket a fender stuffed up one's jersey is a lot better than nothing

If there's the potential of being trapped below a boat or structure by the buoyancy of a lifejacket, remember the tab on the cap of the mouthpiece; insert this tab into the end of the oral inflation tube it's attached to to deflate the lifejacket.

 

[elenya]

We use different bouyancy ratings depending on the person physical size and weight. Our enforcement officers use a 195 as they carry body camera, torch, baton, handcuffs etc. for my personal use i use a lighter 150 jacket as i only have a knife, torch and plb on me.
There must be a fair bit of personal physique to your choice, I sink if I stop swimming in freshwater, others may well be naturally bouyant. I guess only experimenting will find the correct one for you. I find the larger bouyancy jackets impede my ability to self rescue as they keep me on my back too much and extend fyrther in front and to the sides.

 

[ShinyShoe]

I find the larger bouyancy jackets impede my ability to self rescue as they keep me on my back too much.

And that is the reason they have increased the Newton's...

The OP asks why... You have beautifully illustrated it!

A 50N buoyancy aid will keep the wearer afloat but not with face out the water if unconscious.

A 150 should. But, land face down with oilskins on and it struggles to turn you. The testing is in a calm swimming pool with swimming trunks on...

As pointed out you can deflate if too much is in. But I'd rather have 195 and drop to 150 than be 150 and not be turned...

I have a buoyancy aid for situations I expect to be in water so the 195 is for when it's gone very wrong...

 

[Daydream believer]

Maybe worth a couple of reminders here of things people tend to forget or not be trained;

If caught out without a lifejacket a fender stuffed up one's jersey is a lot better than nothing
.

& if someone is still aboard & has half a dozen fenders on the aft rail held with slip knots they can lob them at you fairly quick in the hope that you might grab at least one -- Now why would I have said that ???????:encouragement:

Sorry everyone private joke

 

[MikeCC]

150N is just where the standard sits. In the 150N certification, there are only 33g or 38g CO2 cylinders. 33g of CO2 is approx 18 litres in normal conditions, giving approx 180N. Approx because it will depend on temperature and water salinity (and my gravity rounding) 38g is proportionallly more of course.

So a lifejacket can be a 150N and a 180N at the same time. Of course the higher figure is much more appealing from a marketing view. If you're concerned about level of buoyancy (either way), look at the cylinder weight.

There are more 38g LJs on the market than before though.

Lifejackets are designed to take a lot more volume than just the CO2 in case they have been orally inflated before firing or topped up after so there's scope for even higher buoyancy.

Overall I'd be more interested in having a sprayhood and light than precise level of buoyancy.

 

[[70521]]

Unless the 150N jacket was becoming fully submerged an increase in size has negligable extra benefit. Why then the creeping increase, the height of the body in the water is going to be much more effected by having the jacket snugly fitted with a tight crotch strap than the size of the baloon waving in the breeze.

Speed of turning an unconscious body face up in the water.

Having gone for an "accidental swim" from the dingy I was surprised how slowly my jacket inflated, well that was my perception of the incident.

 

[Daydream believer]

Having gone for an "accidental swim" from the dingy I was surprised how slowly my jacket inflated, well that was my perception of the incident.

That is surprising because when my wife's Crewsaver LJ was sent for service & test she put it on in the lounge first & did a test inflation. It inflated with such speed that it forced her head back very sharply & the seam of the piece that came under her chin actually drew blood

 

[[70521]]

That is surprising because when my wife's Crewsaver LJ was sent for service & test she put it on in the lounge first & did a test inflation. It inflated with such speed that it forced her head back very sharply & the seam of the piece that came under her chin actually drew blood

Oddly no!

I set off a LJ at the London Boat Show part of a demonstration and not me being naughty that LJ went bang and inflated instantly! By the way unless Spinlock have redesigned their manual inflation chord you need arms down to your knees for it to work!

I've put the diffrence down to the density of air and water, water being far more dense.