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Old 02-12-2011, 06:34   #16
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Re: Which Auto Life Jacket

thanks for the links.
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Old 02-12-2011, 17:49   #17
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Re: Which Auto Life Jacket

Dave-
"It has though been pointed out to me that the drawback of 275N units is that they are very difficult to swim in "
In my limited experience, all the PFDs come with an oral inflation tube which is also a deflation tube. Even the standard "150" vests are almost impossible to swim with, a backstroke or sidestroke being recommended. But if you want more mobility, the answer to to release some gas from the vest so it is less bulky. Then blow more in as needed later.
IIRC the Practical Sailor tests that were done some time ago also pointed out that several of the 150n vests will turn the user face-up in the water correctly--IF the vest has been correctly adjusted. No, you can't just throw them on and expect much of anything, these are tools that require operator training in order to function correctly, and that was the original argument against NOT certifying them for public use. Even though our our Secret Service was using them on presidential escort duty for years before that.

I've a hunch that the Hammar, which does not show you any illustration but refers vaguely to "When the inflator is immersed in water by 10 cm, the hydrostatic valve opens and water will have access to a water sensitive element. This in turn releases a stainless steel spring mechanism, " is the one that is just a flap valve protecting an aspirin tablet. You could translate their statement this way:

"When the inflator is immersed in water by 10 cm, the hydrostatic valve opens and water will soak an aspirin tablet. This in turn crumbles and releases a conventional stainless steel spring mechanism, "

What I would call a true hydrostatic release? Would be something like a glass tube, crushed and shattered by water pressure, releasing parts that had been joined. Or, a hyrdaulic piston, activated by the excess water pressure now building on one side of it, moving the piston and tripping something at the other end. Or, you could take the pull tag on a manually inflated vest, tie a beach ball onto it, and THAT would be a hydrostatically activated vest. You fall in the water, plunge down, the beach ball stays up and pulls the string...voila, hydrostatic release. <VBG>

Calling these things a hydrostatic release...That's mistaking the sizzle for a good steak. Clever advertising (oh, our product is SO higher tech) but all it really means is that they've found a way to keep the tablet drier than it is in other configurations, making it more reliable against accidental deployment. (The tablets are infamous for sogging apart and causing false inflation, the vests should be stored with them out.)

A pressure sensor that detected six(?) feet of submersion, then sent power to a small explosive charge that activated the inflator, now THAT would be a true hydrostatic inflator. The same explosive charges that are used in car air bags would work perfectly well, they're quite conventional technology these days.

Try explaining THAT to a TSA baggage thief. Ergh, inspector. (Shh, they catch and prosecute hundreds of employees every year for that problem.)
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Old 03-12-2011, 02:06   #18
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Re: Which Auto Life Jacket

Blimey I certainly stirred up a lively discussion. I've gone for the Marinepool 'Iso Security' Automatic with 165N. I am fairly large so have aired on the cautious side of the N rating but need to keep down the bulk when inflated so I can get back in the boat if the worst should happen. Taking off the jacket to get back in is not an option especially as I mainly do single-handed sailing.
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Old 03-12-2011, 02:16   #19
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Re: Which Auto Life Jacket

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Originally Posted by John Tonks View Post
..... but need to keep down the bulk when inflated so I can get back in the boat if the worst should happen. Taking off the jacket to get back in is not an option especially as I mainly do single-handed sailing.
Quote:
Originally Posted by hellosailor View Post
.......
In my limited experience, all the PFDs come with an oral inflation tube which is also a deflation tube. ....... But if you want more mobility, the answer to to release some gas from the vest so it is less bulky. Then blow more in as needed later.
My limited experience is the the same as Hellosailor so does the Marinepool 'Iso Security' Automatic come with the oral inflation / deflation tube?

If so, that is the answer for getting back on board.
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Old 03-12-2011, 03:14   #20
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Re: Which Auto Life Jacket

Having had the pleasure of spending 4hrs (they lost me) in a sea survival practical in the Irish sea the last thing you need to do is start mucking about with your jacket in a stressful situation with very cold hands
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Old 03-12-2011, 03:53   #21
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Quote:
Originally Posted by hellosailor
Dave-
"It has though been pointed out to me that the drawback of 275N units is that they are very difficult to swim in "
In my limited experience, all the PFDs come with an oral inflation tube which is also a deflation tube. Even the standard "150" vests are almost impossible to swim with, a backstroke or sidestroke being recommended. But if you want more mobility, the answer to to release some gas from the vest so it is less bulky. Then blow more in as needed later.
IIRC the Practical Sailor tests that were done some time ago also pointed out that several of the 150n vests will turn the user face-up in the water correctly--IF the vest has been correctly adjusted. No, you can't just throw them on and expect much of anything, these are tools that require operator training in order to function correctly, and that was the original argument against NOT certifying them for public use. Even though our our Secret Service was using them on presidential escort duty for years before that.
I know from direct experience, with 150N, that any largish male wearing full off shore gear will not be turned face up. This is with crotch straps. As to releasing gas, it's easier said then done.


Quote:
I've a hunch that the Hammar, which does not show you any illustration but refers vaguely to "When the inflator is immersed in water by 10 cm, the hydrostatic valve opens and water will have access to a water sensitive element. This in turn releases a stainless steel spring mechanism, " is the one that is just a flap valve protecting an aspirin tablet. You could translate their statement this way:
I used to have a number of Hammar jackets. Not any more. The problem is the re arming Hammar actually don't support user re-arming, but on a boat that leaves you without a life jacket. Even when you rearm it you need a special key and there's no real way to verify that you have done it properly. I went back to the conventional units. ( united moulders) I've been in some very very wet weather and wave drenching and not ha d the jacket go off.

Quote:

"When the inflator is immersed in water by 10 cm, the hydrostatic valve opens and water will soak an aspirin tablet. This in turn crumbles and releases a conventional stainless steel spring mechanism, "

What I would call a true hydrostatic release? ...............
Somewhat of an angels on a pin argument. It is a " mechanism" ( if you regard a mechanism as the whole thing ) that operates due to water pressure.

Dav
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Old 03-12-2011, 03:55   #22
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Quote:
Originally Posted by John Tonks
Blimey I certainly stirred up a lively discussion. I've gone for the Marinepool 'Iso Security' Automatic with 165N. I am fairly large so have aired on the cautious side of the N rating but need to keep down the bulk when inflated so I can get back in the boat if the worst should happen. Taking off the jacket to get back in is not an option especially as I mainly do single-handed sailing.
Again unless the bottle is bigger then the standard that's just a standard 150N rated jacket.

Dave
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Old 03-12-2011, 04:03   #23
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Re: Which Auto Life Jacket

Quote:
Originally Posted by John Tonks View Post
Having had the pleasure of spending 4hrs (they lost me) in a sea survival practical in the Irish sea the last thing you need to do is start mucking about with your jacket in a stressful situation with very cold hands

Who did you upset John, four hours in the Irish Sea, I hope they had given you a survival suit.

Did a similar exercise many years ago in the North Sea, we were given survival suits and 275N jackets, and left to stew in the sea for an hour in about a force 4 while a support boat stood by.
After an hour, they deployed a raft for us, we were a group of 6, not one us us could get into the raft. As for trying to partially deflate a lifejacket to make it easier, well, that was not an option with hands so cold there was no feeling left in them, despite the neoprene gloves, which in turn made using the hands useless.
The only way we got into the raft was after two crew from the support boat made a dry entry into the raft and then hauled us in.
They then sensibly left the raft for comfort of the support boat, and we were left for 4 hours on the raft.
Hasten to add, I wont ever repeat this course
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Old 03-12-2011, 04:14   #24
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Re: Which Auto Life Jacket

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Originally Posted by goboatingnow View Post

I used to have a number of Hammar jackets. Not any more. The problem is the re arming Hammar actually don't support user re-arming, but on a boat that leaves you without a life jacket. Even when you rearm it you need a special key and there's no real way to verify that you have done it properly. I went back to the conventional units. ( united moulders) I've been in some very very wet weather and wave drenching and not ha d the jacket go off.

Dav
Hi Dave,
Maybe the newer type Hammar releases are more user friendly.
I have one on my spinlock, and we also use them at work. The special key is just an aid to release the locking bit which allows the yellow part of the actuator to be turned and released, a small screw driver works just as well.
If you purchase a re-arm kit, the special key comes with it.

CM Hammar
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Old 13-02-2012, 10:52   #25
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Re: Which Auto Life Jacket

On the ###N ratings for PFDs: Yes, bulky is a problem and remember these things are always built to a price, i.e. less is cheaper and sells more.

I had a SCUBA buddy get in trouble some years ago and needed to get both of us to the surface using just my vest, essentially a PFD. It was terribly convenient to have a vest that had 50% more lift than most, because it floated BOTH of us with our faces well above the water. That's one reason you may want a PFD with extra lift capacity, it may be lifting more than just you.

Then too, any portion of the PFD that is out of the water provides zero buoyancy. So the larger the lift capacity, the more likely you are to be raised clear of the surface. Foulies are coming with spray masks now, because apparently if your mouth is within six inches of the surface, enough spray can blow across to drown you. Every extra inch UP that you can get, makes it easier to breath instead of inhaling water.

And yes, AFAIK there's always an oral inflator/deflator, so you can always let some gas out if you want to slim it down. The actual packed size/weight of the jacket, about the same. Cost of the cylinder, not much different, and you can often use the smaller cylinder, you'd just need to orally inflate the rest of the way.
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