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Old 15 January 2020, 03:25   #1
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Lifejackets-too many Newtons?

Morning all.
Considering a new life jacket......

I don’t wear a drysuit, use waterproofs+fleece layers as necessary, but the 290N jackets have caught my eye.
Was perfectly happy with my 190N jacket until I started thinking!
Is 290N overkill?

Does anyone have insight into the benefits/pitfalls of the extra buoyancy?

Whichever new jacket, it will have spray hood, light and plb attachment and be serviced regularly so only interested in thoughts on how many Newtons are too many Newtons.

Thanks in advance.
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Old 15 January 2020, 04:31   #2
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Originally Posted by Iron Dials View Post
Morning all.
Considering a new life jacket......

I don’t wear a drysuit, use waterproofs+fleece layers as necessary, but the 290N jackets have caught my eye.
Was perfectly happy with my 190N jacket until I started thinking!
Is 290N overkill?

Does anyone have insight into the benefits/pitfalls of the extra buoyancy?

Whichever new jacket, it will have spray hood, light and plb attachment and be serviced regularly so only interested in thoughts on how many Newtons are too many Newtons.

Thanks in advance.
wear three 290N jackets then you wont even touch the water, you can just float home on the wind like a balloon.
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Old 15 January 2020, 05:20   #3
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I would like to be able to enjoy the helicopter ride, if it ever cropped up
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Old 15 January 2020, 06:18   #4
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If you don’t need 290N I wouldn’t buy one. There’s a penalty to be paid with bulk & weight.
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Old 15 January 2020, 08:11   #5
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I agree with Dave and would not go to a 275N or greater.

I was in a similar dilemma and thought that bigger would be better but reading round the subject, it probably isn't the case.

https://rnli.org/-/media/rnli/downlo...aids.pdf?la=en

https://www.rya.org.uk/knowledge-adv...fejackets.aspx
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Old 15 January 2020, 13:26   #6
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if your 190 jacket is due a service I suggest actually putting yourself in the sea in a swell in a controlled manner and see for yourself what poor buoyancy feels like, a lot of people are under the illusion that you life jacket will keep your head out of the water in a swell. you may find yourself being ducked under water with a frequency related to swell and the buoyancy of your jacket.two of us found ourselves in this situation some years ago where we got overturned and pelted out our rib, we spent nearly an hour in the water. I was ducked under consistently but my mate had a different problem ,he never fastened the
under crotch straps with the result that every swell tried to take the jacket over his head.two valuable lessons learned Try the jacket for buoyancy and wear it properly.
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Old 15 January 2020, 14:31   #7
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I'm with mikehhogg. You'll weigh a good deal more than your dry weight once your clothing is saturated and boggin wet.

I wear 275, I guess it will be pretty cumbersome trying to climb back into a boat but if I'm able to get back to a boat with a chance of getting back in after a capsize, air can be released if necessary.

I don't notice any appreciable difference wearing it compared to a jacket with less buoyancy.

However, it's guesswork since the only time I've swum in one is in a pool session and I was pulled aboard backwards so the jacket didn't make any difference. Well, perhaps it did, I'd be floating higher...
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Old 16 January 2020, 02:23   #8
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I'm with mikehhogg. You'll weigh a good deal more than your dry weight once your clothing is saturated and boggin wet.
...


Assuming we’re talking about in the water & not on the dry, then surely your displacement would be the same regardless of whether your clothes were wet or dry. You’d lose any residual buoyancy after any trapped air was lost, but your weight would remain the same. Wet clothing isn’t going to drag you down....is it
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Old 16 January 2020, 03:36   #9
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I would like to be able to enjoy the helicopter ride, if it ever cropped up

You have to balance that against the possible risk that the bigger jacket makes you more likely to need the heli. There’s no definitive answer for that it depends where you go, who with, the conditions you find yourself in and even how you drive the boat.

Bear in mind though that probably more LJs get activated falling off pontoons, tenders, tying to mooring boys etc than in MOB incidents - and self recovery in those situations is difficult. Just swimming a few metres to a suitable place to get out is hard enough in a 150N - a 275N will be harder. For some reason people don’t tend to deflate jackets when they struggle as JW suggests you could. He’s a wise and experienced boater with a generally logical and rational mind but I wonder if he’d still be thinking that clearly after the sudden shock of immersion or 20 minutes in the cold trying to get back to the boat.

I think if you boat alone then making sure you have an effective means of calling for help securely attached to you may be more critical for your noisy, cold and uncomfortable flight than 85 extra N unless you are at the more extreme level of trips people do on here.
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Old 16 January 2020, 08:50   #10
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Assuming we’re talking about in the water & not on the dry, then surely your displacement would be the same regardless of whether your clothes were wet or dry. You’d lose any residual buoyancy after any trapped air was lost, but your weight would remain the same. Wet clothing isn’t going to drag you down....is it
No, it won't drag you down but waves will lift you by the LJ and trapped water within your clothing is not free flowing so the LJ will also need to lift that weight. Moving in water in saturated clothing is difficult.
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Old 16 January 2020, 10:03   #11
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No, it won't drag you down but waves will lift you by the LJ and trapped water within your clothing is not free flowing so the LJ will also need to lift that weight. Moving in water in saturated clothing is difficult.


Eureka!!
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Old 16 January 2020, 14:50   #12
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I’ve seen various lifejackets go off as most people have but I once witnessed a MOB out at sea on a commercial job and the bloke had a 275n Lifejacket on. I was astounded by the size it inflated to, it was like a single instant armchair around his head after what sounded like a gun shot. He wouldn’t have got back in the boat without help.


I remembered an Instructor, a very experienced bloke telling me never to wear a 275n because if you go under an overturned boat wearing one, you wouldn’t get out unless you slipped the lifejacket. It all made sense when I saw how big an item that they inflated to.


I'm sure they are great if you fall off an oilrig in heavy clothing with boots, if you survive the fall and impact.
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Old 16 January 2020, 14:58   #13
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I’ve seen various lifejackets go off as most people have but I once witnessed a MOB out at sea on a commercial job and the bloke had a 275n Lifejacket on. I was astounded by the size it inflated to, it was like a single instant armchair around his head after what sounded like a gun shot. He wouldn’t have got back in the boat without help.


I remembered an Instructor, a very experienced bloke telling me never to wear a 275n because if you go under an overturned boat wearing one, you wouldn’t get out unless you slipped the lifejacket. It all made sense when I saw how big an item that they inflated to.


I'm sure they are great if you fall off an oilrig in heavy clothing with boots, if you survive the fall and impact.


To be fair, 175N or 275N, you’re going to struggle to get from under an upturned boat either way. Especially in the blind panic that’s going to accompany such an event. I’d think that most on here (with open RIBs not cabin RIBs) would be thrown clear of a capsize.
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Old 16 January 2020, 17:40   #14
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Thanks very much folks.

I think you're all correct, apart from the balloon idea
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Old 16 January 2020, 18:41   #15
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you can let air out of the larger lifejacket and make it less buoyant but you cant make a 180 more bupyant
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