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Old 22 January 2012, 14:07   #51
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Happened to me once on one of my first dives after qualifying. Trying to stay horizontal at 20m but the air ran up my legs and inverted me. Started to accelerate upwards but caught it about 5m. Got a bit of a scare but swam back down to depth to recompress. Just inexperience making me slow to react. Dead easy to get confused in all the bubbles. Once you know the feeling all it takes to correct it is a bit of gentle finning.

On the cat I suck out all the air before we set off to minimise the buoyancy in case we go for a swim. Either I wade in to neck level and break the neck seal with a finger or I pull the seal over my top lip and suck out all the air until I'm vacuum packed.

Offshore survival suits used to have a zip up section on the legs to tighten it in. Now they have ankle relief valves.
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Old 22 January 2012, 14:08   #52
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Let go a delayed smb. You can hit the surface from 30 m in under a minute. Where will you get the time to do that

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Old 22 January 2012, 14:55   #53
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Wearing my surface drysuit, I came perilously close to what felt like inverting at the Priory Bay picnic the first year I had this particular drysuit.

I went for a swim from the beach in it without venting it properly and as I was on my face, all the air went to the legs and my head went under.
I may be wrong, as it was easily recoverable-I was in 3 feet of water so I just stuck my hands on the bottom and pulled my feet under me. I've made sure it's vented properly since.

The way I see it is if I go overboard at speed,I don't need the possibility to add to my worries.
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Old 22 January 2012, 15:15   #54
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Quote:
Originally Posted by Mr Flibble View Post
Fire a Delayed SMB from depth, it'll hit the surface vertical,if not under tension it'll lay flay on the surface, by somes reckoning it should stay vertical, it doesn't.
Have I missed something What has a delayed SMB got to do with drysuit venting?
If you want to keep you SMB vertical ensure that you are slightlly negatively bouyant when ascending and winding in, although I have never felt the need. I guess it depends on just how switched on you surface cover is.
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Old 22 January 2012, 20:15   #55
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Have I missed something What has a delayed SMB got to do with drysuit venting?
If you want to keep you SMB vertical ensure that you are slightlly negatively bouyant when ascending and winding in, although I have never felt the need. I guess it depends on just how switched on you surface cover is.
Yes you have.
Discussion was about jumping in head first off a RIB with air in drysuit. Would you stay inverted? I was merely pointing out to those that claim you do that if that were the case then a DSMB (which like a drysuit is essentially a bag with air in it) would act in the same manner, ie as it ascends vertically it would stay vertical when it breaks the surface, it doesn't it lays flat on the surface as the whole device has bouyancy. To keep it vertical you either attach a weight to the bottom or act as the weight yourself. A drysuit will act in exactly the same manner. Physics is physics. To keep a drysuit fully inverted you would need to either attach a weight to your head (to counteract the natural bouyancy of head, lungs etc) or stay completely vertical so that all the bouyant force is acting on the highest point of the drysuit (the feet), any deviation from this will result in bouyancy lifting. When snorkelling, I've hauled myself down a weighted line in my drysuit, let go and did a rapid ascent feet first. I hit the surface feet first then end up floating horizontally (usually face down) and don't stay inverted and drown. In answer to the OP's question. You tend to bend your knees slighty when lying flat/face down, this raises your feet higher than your head and will result in a slight head down attitude when floating on the surface but doesn't cause full invertion. Drysuit wearers should become adept at moving/swimming in their suits as without fins on face forward swimming is usually with hands alone.
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Old 22 January 2012, 20:23   #56
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Let go a delayed smb. You can hit the surface from 30 m in under a minute. Where will you get the time to do that

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Sorry I don't get your point here. I frequently use delayed SMB's. They are designed to be used from depth.
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Old 23 January 2012, 03:15   #57
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Sorry I thought we firstly was talking about venting suits and then slightly hijacked the post by explaining about Boyles law. Ie the compression of gasses under pressure.
The only way I could read your post in this instance was to think that you were looking at deploying a DSMB while you were heading for the surface like a Polaris misslie

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Old 23 January 2012, 13:42   #58
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These will keep your feet pointing down

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Old 23 January 2012, 16:06   #59
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Only once got caught out.

Working on a heavy chain in Faslane, Scotland, the exercise was to saw through a 2 inch link. Got so tired and frustrated, feet went higher than body and got inverted. Fortunately was neutrally bouyant and was able to roll back upright.

Had to buy the beers that evening back in the mess though ....
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Old 23 January 2012, 18:17   #60
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To the OP and any others, practice swimming in your drysuit. Vented, unvented, with and without a lifejacket. It doesn't take long to get comfortablewhich is really what this is all about. That way when you do go ass over tea kettle out of the boat you'll have the experience and skills to cope with your shocking immersion.
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