Buoyancy in inflatable vests - SailNet Community
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post #1 of 27 Old 01-24-2016 Thread Starter
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Buoyancy in inflatable vests

What does it mean when a vest is rated at a certain buoyancy? For example: What should the proper buoyancy given a certain weight of individual?
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post #2 of 27 Old 01-25-2016
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Re: Buoyancy in inflatable vests

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Originally Posted by Gregrosine View Post
What does it mean when a vest is rated at a certain buoyancy? For example: What should the proper buoyancy given a certain weight of individual?
It doesn't really relate to weight of the individual. Most people float to start with so not much buoyancy is needed. Mustang has pfd's with 26 and 35 lbs of buoyancy.

Brian
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post #3 of 27 Old 01-25-2016
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Re: Buoyancy in inflatable vests

Bouyancy isn't as much importance here as keeping the face up, and out of water. As mitempo mentioned, most people are naturally bouyant, more so if they are Walmart patrons, even more so after they have stewed at Sea a few days.
I once took a Scuba Diving Class, and one test that was made was how much added Lead weight was needed to be neutrally bouyant at reasonable depths- I needed none. A natural Sinker.

Unless taking such a Class, the only way to tell is to try it out in Water, Salt or Fresh as appropriate. If you can float on your back, with limbs extended, and can just muse on the sky, you are bouyant. If your arms and legs hang down, and you go under when exhaling, you are not.
In any event, the Importance is keeping your face up and out of the water, especially if unconscious. Pretty much everything else is secondary.

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post #4 of 27 Old 01-25-2016
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Re: Buoyancy in inflatable vests

Amazed at how many people don't attach a spray shield to their harness/inflatable pfd. Most people don't realize due to the way your arms and legs bend and their relative length you will tend to revert to facing on coming waves in any sort of a seaway. You may drown even floating face up. The spray hoods or shields are very cheap.
A good set up is the pfd/harness, locator of some sort, led flare, spray shield and line cutter or serrated knife. All add ons less than $60-70 ( except locator - like AIS ones) even going high end. If going offshore or anything beyond day sailing coastally use only hydro not salt pills.
Inflate at least once a year for >16h to check for leaks and periodically and before passage.
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Last edited by outbound; 01-25-2016 at 10:33 AM.
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post #5 of 27 Old 01-25-2016
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Re: Buoyancy in inflatable vests

I sink.. my wife floats no problem. So the PFD really only has to provide enough bouyancy to make up for anyone's difference between their weight and their displacement. Mustangs' standard numbers is likely more than enough for anyone.

But if you have a lifejacket that's 'rated' for a 150 pound person, it will sink if you hang 150 pounds of lead off of it. Even 50 lbs would do it.

Ron

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".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
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post #6 of 27 Old 01-25-2016
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Re: Buoyancy in inflatable vests

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Originally Posted by Gregrosine View Post
What does it mean when a vest is rated at a certain buoyancy? For example: What should the proper buoyancy given a certain weight of individual?
Hi Greg,

I understand the reason that some inflatable PFDs are offered in different buoyancy ratings to accommodate either large individuals, or individuals who carry extra weight when wearing the PFD [e.g., tool belts, etc.]

As an example, the vests we use [Spinlock 5D DeckVest with built-in harness] are offered in 2 buoyancies: 170N [38 lbs] and 275N [62 lbs].

Following is a snip from Spinlock's FAQs regarding the different buoyancy ratings:
Quote:
Should I buy a 170N or a 275N Deckvest?
170N is the accepted standard for recreational sailing. It is a comfortable, wearable size that is not too intrusive and it provides significant buoyancy when in the water. The 275N provides significantly more buoyancy so is suitable for larger people and situations where additional weight might be carried, i.e. tools, steel toecap boots, etc. Remember additional buoyancy and size is not always an advantage as it is heavier to wear and harder to use in the water, i.e. if entering a liferaft, etc.
In case this is helpful.

Cheers!

Bill

PS: We constantly remind ourselves and our guests that inflatable PFDs on US Flagged vessels only count toward the USCG approved PFD inventory if they are being worn... [Side Note: The Spinlocks we wear and referenced above are not currently USCG approved. Therefore we have additional PFDs onboard that are approved in case of inspection...]


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Last edited by wrwakefield; 01-25-2016 at 02:01 PM. Reason: Added PS.
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post #7 of 27 Old 01-25-2016
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Re: Buoyancy in inflatable vests

Please understand something about buoyancy ratings: MORE IS BETTER.

It is not a matter of what you weigh or what YOU will need. I had to assist a scuba buddy who had an air failure, their BC wouldn't inflate either. So *my* BC, which had a very large buoyancy rating, was adequate enough to get BOTH of us well above the water.

If you go overboard and someone else goes in with you, or after you, you may very well well be happy to find you have "TOO MUCH" buoyancy. You can always bleed some out if it is too much. And if you need to swim at all, you will have to bleed most of it out unless you sidestroke or backstroke. They're designed to get your face up out of the water, and any modern one that doesn't come with a spray shield is strictly an "inland" PFD. That's been mandatory for some years now on offshore gear, because just the spray from a good breeze or rain, is enough to make you inhale water and drown in otherwise manageable conditions.

Check out the online reviews, and if you've never used one, check your out as well. In the water. If it doesn't turn you face up, send it back. And learn to use crotch straps. Without them, the vest rides up, and any portion of the vest that is above the waterline? Isn't providing any buoyancy at all.

Less buoyancy=less material=cheaper PFD.
Is "cheap" the way to buy lifesaving equipment?
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post #8 of 27 Old 01-25-2016
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Re: Buoyancy in inflatable vests

We carry several inflatable vests all set up with the add ons. That way crew or guests get a choice. But far and away my favorite is not an inflatable but rather a Baltic. Except in the tropics find it the most comfortable and the foam acts as padding so has prevented some bumps and bruises. Lots of nice pockets and have set up stuff on lanyards attached inside the pockets. Still room for snacks to get through night watches. In storms the exposure suits the oil guys wear seem best. Unlike survival suits your feet and hands are free. Can't image getting into a gumby suit with it rocking and rolling while sinking. One piece so easy on/off. Dry and warm. Don't like any of the inflatables. They pull on you and are hard on your expensive foulies. If you actually fall all the forces are communicated to just the straps and leave bruises.
Think people might be pleasantly surprised if they look at the commercial stuff rather than just limiting themselves to yachtie stuff.

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post #9 of 27 Old 01-26-2016
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Re: Buoyancy in inflatable vests

It's also good to note that the Spinlock Deckvests come with all the above mentioned add-ons plus leg straps, water-activated strobe and lifting strops. Spinlock also offers a manual-only coverter you use to remove the auto-inflate feature of the Deckvest. This is important if you're below deck when things go sideways...

Quote:
Originally Posted by wrwakefield View Post
Hi Greg,

I understand the reason that some inflatable PFDs are offered in different buoyancy ratings to accommodate either large individuals, or individuals who carry extra weight when wearing the PFD [e.g., tool belts, etc.]

As an example, the vests we use [Spinlock 5D DeckVest with built-in harness] are offered in 2 buoyancies: 170N [38 lbs] and 275N [62 lbs].

Following is a snip from Spinlock's FAQs regarding the different buoyancy ratings:


In case this is helpful.

Cheers!

Bill

PS: We constantly remind ourselves and our guests that inflatable PFDs on US Flagged vessels only count toward the USCG approved PFD inventory if they are being worn... [Side Note: The Spinlocks we wear and referenced above are not currently USCG approved. Therefore we have additional PFDs onboard that are approved in case of inspection...]
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post #10 of 27 Old 01-26-2016
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Re: Buoyancy in inflatable vests

Quote:
Originally Posted by Cap'n Russ View Post
It's also good to note that the Spinlock Deckvests come with all the above mentioned add-ons plus leg straps, water-activated strobe and lifting strops. Spinlock also offers a manual-only coverter you use to remove the auto-inflate feature of the Deckvest. This is important if you're below deck when things go sideways...
Thank you, Cap'n Russ,

Those are very important points and were among our considerations when we were searching for inflatable PFDs.

Another thing I didn't mention was we installed the AIS transmitters [with GPS] for POB alerting. They mount and deploy very well on these vests- automatically activating when the vest inflates. [We test annually...]

As a side note, when our AIS transmitters need replacing, we will likely go with the newer combination DSC/AIS POB transmitters for additional redundancy...

Thanks again.

Cheers!

Bill


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Last edited by wrwakefield; 01-26-2016 at 04:31 PM. Reason: Added OS MOB1 link.
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