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Old 18 January 2012, 17:03   #21
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Quote:
Originally Posted by Pikey Dave View Post
Nope not a myth. I was once dragged up from 45m to 20m by a diver who had lost his weight belt & inverted. I let him go at 20m or we would have both finished up in the chamber. He spent 3 days in hospital.
Thats with tanks though which will weigh your upper body down.

Regards neoprene suits how people in RIB's use em as a surface drysuit apart from divers?
I never saw any divers in neoprene suits when I used to go.
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Old 18 January 2012, 17:12   #22
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I never saw any divers in neoprene suits when I used to go.
It's about a 50/50 split between membrane & Neoprene drysuits among the diving fraternity
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Old 18 January 2012, 18:03   #23
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Interesting thread. We wear drysuits with latex neck seals and feet during the winter to hydrofoil. You are supposed to wear a life vest, but not everyone does because of the bulk with so many layers. Every time we return to the boat we unstrap from the foil set up and swim to the swim step. I have never had a problem regarding orientation. I often roll head down to pull sea grass off my t bar. Never had an issue coming back up. If you don't burp a little air out of the drysuit before foiling impacts can force air out your neck seal and you will get a bit of a cold water forced in. Not fun. I would be more concerned about hitting the water when exiting the boat, burping the seal and getting cold from the momentary flush rather than whether or not I might float heads down. In a survival situation that would be less than ideal. In my case it just amuses your friends in the boat.

I know a lot of boaters wear drysuits with neoprene neck seals since they are more comfortable for long term use. Neoprene neck seals are much more prone to leakage and should be monitored for stretching or deterioration. Leaking drysuits are definitely a safety hazard if there is no one there to pick you up.
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Old 18 January 2012, 18:36   #24
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Originally Posted by captnjack View Post
Right.
Are you actually a diver? Have you tried floating head down feet up at the surface? Just a suit on no weighbelt or tank etc. You can't do it. There is residual air in the chest portions of the suit, there's some gas in your lungs too, there's adipose tissue. Your head is not a massively negative weight with these purportedly bouyant feet sticking up in the air like a buoy.

Really just dive in sometime. You won't float feet up. Within a few seconds you will be horizontal. Face down maybe but roughly horizontal. Then just roll over.

I would still recommend life jackets despite the inherent bouyancy of a drysuit.
On this note, I am qualified and during my training discovered that without buoyancy, in SCUBA kit, I come to rest underwater upside down. I need ankle weights to redress the balance.....not that uncommon.
Without venting if you go in head-first, be prepared for disorientation and an unnecessary struggle which may just be enough to beat you dealing with cold water shock.
ALWAYS VENT
ALWAYS VENT
ALWAYS VENT
It's a squat with your hands pulling your collar for a few seconds, release the collar and stand up. VENT!!!!!!
Like wearing a seat belt, takes a few seconds to put on and why the hell not?
If your suit would happen to have a small leak when in the water, if you're horizontal the water will pool at the lowest point. You will find it harder to go head up.
Vent and make sure you are balanced so that your feet stay below you. Once in the water you can vent upright by putting hands above your head and opening one cuff with the other hand to release trapped air.
VENT
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Old 18 January 2012, 18:37   #25
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If you upend in a membrane suit (ie do a surface dive) you WILL hang head down.
As others have said, just you, undergarment, and suit the answer is horizontal. And it doesn't matter what type of suit it is. Try it with manual only inflate lifevest to "save yourself" if you're skeptical.

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in SCUBA kit
Yes with tank on you're probably going to end up head down. Without all that compressed gas, steel and lead you'll float roughly horizontal. Certainly horizontal enough to just roll over if your mouth is in the water.
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Old 18 January 2012, 18:38   #26
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I think there has been incidents and maybe deaths if i remember where a person has been inverted ,
usually from wearing a neopreane dry suit that dident fit proper or a much smaller person using the suit having too much baggyness in the lower leg and with the stretch of the neopreane adding or ballooning possibly more so than a membrane suit that wont stretch as much ,
though a lot will also depend on what type of feet there is too
the membrane latex sock is more likely to stretch or ballon rather than a harder boot eg the welly type ,

if you are wearing a life jacket as you should there should be no problems .
mart
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Old 19 January 2012, 01:31   #27
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Quote:
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It's about a 50/50 split between membrane & Neoprene drysuits among the diving fraternity
I never saw one person where a neoprene suit, maybe times have changed over the last ten years?
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Old 19 January 2012, 02:36   #28
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I think the incident that started this post was refering to a different type of suit?? years ago there was a FLOTATION suit manufactured, that was 2 piece auto inflate, big problem, we tried it, and YES you ended up floating feet up torso down, very frightning!!!!, hence it was withdrawn from the market, Thank F---, it was intended for use by angerlers etc.
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Old 19 January 2012, 03:47   #29
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Quote:
Originally Posted by jyasaki View Post
Doesn't matter where it is. Air in the suit is free to move to the less pressurized area, i.e. the last thing to dip underwater. Water pressure will shrink-wrap the submerged part of the suit to your body, and the bubble ends up at the surface. As has been said, if you are feet-up, curl up in a ball, right yourself by swinging your arms, the extend your legs. The bubble will move to the torso and neck of the suit and your equilibeium will be restored.

jky
Pretty much the way I see it.Pikeys point about being dragged UP by another diver is moot,as we're talking about surface invertion.Although haveing experianced something similar myself with a Novice diver once, it's not pleasant.The Joys of ''Boyles law'' do not impact on the surface.
Personaly I think we'd all rather find ourselvs in the water in a good Dry suit,Neoprene or membrane, (Not to mention Lifejacket) and have the pretty minor inconvieniance with a bit of air migration..Rather than freezeing to death in a short period...most likely befor rescue!
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Old 19 January 2012, 06:02   #30
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Quote:
9D280 (or possibly more likely in a dinghy - bouyany aid) kind of doesn't give it much room to stay there as it compresses the suit round your torso.
Good point, when wearing a PFD / BA it does fit very tightly round the chest so does stop excess air getting to the torso of the suit making it difficult I would have thought to curl up and expel air from the legs. Although this might not invert a person fully while on your back, with the excess air in the legs it could keep your head slightly under the water line to cause problems, especially in choppy water.
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Old 19 January 2012, 07:50   #31
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The RN "one only" survival suits have ties around the legs to help prevent air ending up in the wrong place once you've abandoned ship.
Implemented after the Falklands War IIRC.
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Old 19 January 2012, 11:08   #32
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Good point, when wearing a PFD / BA it does fit very tightly round the chest so does stop excess air getting to the torso of the suit
No it won't. You'd have to crank the straps down to where you couldn't breathe to get the straps to stop airflow. The air will find its way through the smallest fold in the suit material, and flow through the fabric of your clothing. It won't have any problem getting through the restriction imposed by a PFD over the outside.

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Old 19 January 2012, 11:18   #33
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Attachment 64993

Look no adipose.

Holy God! I turn my back for three days and you're impersonating the young Keith Chegwin. What next?
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Old 19 January 2012, 11:51   #34
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Holy God! I turn my back for three days and you're impersonating the young Keith Chegwin. What next?
Now i thought that he was chubby
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Old 19 January 2012, 12:18   #35
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I see my photos got deleted
But on a serious note what effect will the new and old Gecko helmet have on a person in the water.
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Old 19 January 2012, 17:42   #36
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I see my photos got deleted
But on a serious note what effect will the new and old Gecko helmet have on a person in the water.
Old square shape large size weighs with visor 668 grams.
Mk 10 large size with visor , no inflation bladder 674 grams and seems to float just slightly better.

Think one big inversion risk is when you may get a young smaller person using a drysuit a few sizes too big perhaps and having no life jacket on ,
Inverted the legs could generate more buoyancy than the torso.

Also for those that use a membrane suit for swimming ashore or out to the boat say with no PDF just using the suits bouyancy if the latex neck seal tears your going to loose air and fill up quick.
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Old 20 January 2012, 09:58   #37
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"On this note, I am qualified "
as what exactly MrP ??
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Old 20 January 2012, 10:00   #38
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What are we saying then ?? that, when wearing a dry suit that has not been vented, it is a "myth" that you will end up inverting and possibly drown, or it's a "fact" that you will ??
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Old 20 January 2012, 10:07   #39
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Now i thought that he was chubby
He is, but he still looks better than you with no clothes on......allegedly
WARNING NOT FOR THE FAINT HEARTED OR WEAK OF STOMACH.

There's a joke in there somewhere about Kaiser Kerny & sausages, but for the life of me I can't dig it out
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Old 20 January 2012, 11:02   #40
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Quote:
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What are we saying then ?? that, when wearing a dry suit that has not been vented, it is a "myth" that you will end up inverting and possibly drown, or it's a "fact" that you will ??
Having owned a dive shop with two schools attached too it and been a commercial diver I think I can probably make a guess at the right answer.
Unless you're deformed you should float with shoulder and legs on the surface. If you shift or try to turn over the air can go to your arse so you can float face down. You will panic quick enough to lift your head and float upright.
The easiest thing to do as suggest is squat with your fingers in your neck seal. You don't want excess air in the suit if your wearing a life jacket
When you're diving air shift to legs can be a problem in the not so well trained and I've seen uncontrolled accents from depth and it ain't pretty.
Just get the air out to be on the safe side

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