Hydrostatic deployment on lifejackes - what would happen if...

Judders

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...I manually inflate the lifejacket (i.e. by blowing into the tube) and then the hydrostatic bit blows the cylander as it has got wet?

Could the lifejacket cope or would it pop?
 

CPD

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It would pop, as it would if you put the wrong cylinder (ie larger than spec) on as a replacement.
 

Judders

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So if we are in a position where we feel we should inflate our lifejackets before stepping off the wreck, we should try pulling the chord rather than literally blowing them up.

Nobody ever tells you this but it could be hugely important.
 

alorwin

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Waiting on deck in a floundering boat in possibly severe weather and you get that awful feeling, WILL IT INFLATE WHEN I HIT THE WATER? The truth is not always and from experience I can assure you the same uncertainty applies to liferafts too. A worse scenario is hanging onto everything you can in an inflated lifejacket and then it snags and tears. Don't blame anyone for wanting to inflate before they enter the water but do it at the very last minute with the cord. DONT inflate if jumping from a height, this is ok in a solid lifejacket as long as the correct brace position is adopted but you are pushing your luck with the inflatable version.
 

rwoofer

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I had some lifejackets from 1979 that had written on them "Do not partially inflate before pulling gas cylinder cord". Not sure anyone would read these instructions in the heat of the moment.

They were complete with rusty cylinders so last week I thought I would test them and unbelievably both lifejackets fully inflated. One is still fully inflated a week later!!
 

Hugh Foulis

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When investigating a fatality some years ago it became clear that the automatic firing system had failed. I then found a second instance where the same thing happened, also a fatality. The automatic firing mecahnism should not be relied upon and one should always activate the firing mechanism manually if one has time and is in a position so to do. That way one will know that the jacket has inflated, rather than gambling that it will do it all itself. That said, I went in to the harbour in February and it was all so quick that I hadnt time, thank Baltic that it worked like it said in the book.
Oral inflation should be a last resort and used for topping up, done regularly it puts moisture into the balloon and this is not good for their long term health.

HF
 

Cornishman

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That as the year of the Fastnet disaster, and I recall a comment in the inquiry that followed which suggested that starngulation was too high a price to pay for not reading the instructions. Following that it was decided that pressure relief valves would be fitted to all subsequent lifejackets.
Get an RNLI SEA check and the adviser will give you the full story, including how to look after your lifejackets. Did you know you should inflate them once every six months using a dinghy foot pump and leave them blown up for 24 hours? See PBO/RNLI Safety Card No 1
 

fflakey

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[ QUOTE ]
DONT inflate if jumping from a height, this is ok in a solid lifejacket as long as the correct brace position is adopted but you are pushing your luck with the inflatable version.

[/ QUOTE ]

MYTH

Just jump, if its inflated first it will bring you back to the surface faster. All this talk about breaking necks is rubbish.
 

rwoofer

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I did just bin them this evening, as it is not worth taking the risk with no pressure release valve, even though they still functionally work.
 

fireball

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Hmm - let me think .... I jump from a height into the water - hopefully feet first ... the resistance of the water and my natural buoyancy will (hopefully) slow me down and then bring me back to the surface ...

now - if I jump with an inflated lifejacket around my neck (and it is around the neck - having done a test fire on a rusty cylinder with the rest of the family around to see how it works) .... all of a sudden I have significantly more buoyancy concentrated around my neck area .... so - in I go - and not only do I have the extra resistance of a large item (the inflated jacket) to slow me down, but the extra buoyancy - all concentrated around the neck ... the energy has to go somewhere and I'll wager that a good proportion of it will be trying to seperate my head from my shoulders ...
 

Malcb

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Which is why, if you jump in wth an inflaed lifejacket, it is prudent to cross your arms over the inflated life jacket. Also having a crotch strap would help, as well as making your eyes water /forums/images/graemlins/shocked.gif
 

alorwin

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For benefit of critical quoting FFLAKEY.
RE the myth about breaking necks which I NEVER mentioned.
I am a little unsure why you quote me on something I never said. MY reference to pushing your luck was in relation to the lifejacket which was the subject (not the person who is wearing it). Damage can be done to the inflated chambers when given the impact shock associated from jumping from a height hence part of the reason that they are designed to activate in the water. I speak from personal professional and commercial certification which I have. This training was beyond RYA standard(which I am not knocking at all and would infact recommend) the training and certification was acquired at PENTLAND who train the emergency services oil rig employees and many other commercial sea going people so I do know what I am talking about. I dont mean to be harsh but many people do need safety advice hence they ask and many more are in a position to offer advice freely which could one day be instrumental in saving life . For someone to pass comment about breaking necks and then quote something that never mentioned breaking necks makes me wonder why you are advising on safety issues
 

fflakey

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No

Your natural buoyancy will be nothing compared to the speed of your entry. The drag of your clothing will severely hamper your passage to the surface.

You assume your lifejacket will have a CO2 cylinder..... Hmm, maybe the navy has gone upmarket in recent years. But no matter, any buoyancy will be taken on the harness, not the head hole in the jacket. In a good world this will be on the crotch strap <ouch>, failing that you might have to pull the harness a bit before you deploy your hood once you are on the surface.

Of course this all assumes you have got all the air out of your survival suit before you jump and are not floating with your legs up around your ears giggling uncontrollably whilst surrounded by millions of jellyfish! (Horsea lake anyone?)
 

fflakey

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Alorwin

Sorry but your post seemed to bring up the old myth of not inflating a jacket before you get in the water due to the possiblity of breaking your neck (Hollywood probly takes the blame for this one).

I'm sure any modern LJ would stand up to more pressure shock that I could!

One thing that has not been mentioned here is the cold shock on entering the water. I've been in situations (in training) where the water was so cold I couldnt even take a breath for myself let alone have some to spare for blowing the jacket up!

Hence the drill of 'inflate then jump' (hopefully leading to the cut, stream, close, maintain)

Apologies if I inadvertently offended
 

fflakey

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[ QUOTE ]
oil rig employees

[/ QUOTE ]

Ahhhhhhh, you've done the Dunker then? I hated the bloody thing.

But it did stand me in good stead during a canoe capsize a few weeks later (and also helped a friend on the Herald of Free Enterprise)
 

GaryE

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Ah yes, the Dunker.
Mine is due again next month, apparently they leave the windows in the beast now, so you have to shove them out before departing the premises. Still, at least it's warm water!
 
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