Scuba Geek

Gradient Factors Explained July 19, 2006

Posted by Andy Carroll in : Decompression , add a comment

Over at Yorkshire Divers Garf and Mark Powell have collaborated to produce a nice explanation of Gradient Factors. Gradient factors are used in some decompression software packages to adjust the Buhlmann algorithm, usually with the aim of inserting ‘deep stops’.

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To Exercise or Not to Excercise After a Dive? June 30, 2006

Posted by Andy Carroll in : Decompression, Uncategorized , 2comments

Within my technical diving training and spending many hours reading medical texts, I have always thought the general concensus is that exercising before a dive is fine, but exercising after a dive is a big no no, and empirically I have felt this myself. Whenever I simply chill out and make special efforts not to do anything representing exercise after a dive I have felt better than those times where I have immediately jumped up and hurried around the boat tidying kit away and lifting cylinders about. Obviously me ‘feeling’ better has nothing to do with the bubbles in my system, but it is generally accepted that you could create or aggravate any bubbles by exercising too much after a dive.

Well, this piece of research now suggests that strenuous exercise after dive also reduces bubble formation, therefore turning the whole theory on its head.

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Disabled on scuba dive, man sues Coast Guard and DAN May 8, 2006

Posted by Andy Carroll in : Accidents, News, Travel , 1 comment so far

There is a story in the St Petersburg Times today which tells the story of Timothy Hogan, who was spear fishing in the Gulf of Mexico at 122 feet when ‘His vision had gone blurry. When he blinked, he saw flashes of light, like electrical charges.’

The weird thing is that Hogan then ignored these signs and continued pulling in a 7lb mangrove snapper he had caught. Eventually arriving back on board his symptoms worsened and his toes were tingling, spreading to his legs. Divers Alert network and the coastguard were called, and a rescue was made, but unfortunately he has never walked since.
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DAN America and Chamber Operator, SSS, Reach Settlement April 28, 2006

Posted by Andy Carroll in : Decompression, News , 1 comment so far

It appears that DAN members across America can breathe a sigh of relief that they will be able to get treatment from SSS chambers in the event of emergencies, as they and DAN have settled their previous dispute over treatment fees.

Underwater Times report;

Representatives of SSS announced that DAN America insurance is once again accepted as a result of the resolution of the outstanding claims that were the basis for the lawsuit. The terms of the settlement remained confidential. The SSS Network of Recompression Chambers and DAN America have pledged to work closely together to ensure that injured divers will receive the most appropriate and effective medical care.

Scuba Diving Air and its Effects on Decompression December 25, 2005

Posted by Andy Carroll in : Decompression , add a comment

Firstly, an intro into what happens when we go scuba diving underwater. As you know air is made up of 20.9% or .209 Oxygen and 79.1% or .791 nitrogen there or thereabouts. As we go deeper these numbers or partial pressures increase. So at 10 mtrs or 2 bar its .418 and 1.582 (we show these as Po2 and PN2) as it is multiplied by 2. Scuba diving to 30 mtrs we multiply by 4 bar which is .836 Po2 and 3.16 pN2, you can see how the nitrogen part is growing quite quickly. The oxygen part we don’t really worry about as it is a metaboliser (we do but its not relevant today) and our body uses it in other ways, but the inert gas, the nitrogen, is soaked into our body, we could call it saturation.

You will maybe have heard of fast tissues and slow tissues. We use these terms to describe how quickly the tissue in question is saturated with nitrogen. This is determined largely by bloodflow (perfusion) If a tissue has good bloodflow then it is said to be a fast tissue. The blood itself is a fast tissue, along with the major organs and central nervous system. Slow tissues have poor blood flow such as bones, skin and fat. These classifications are quite important in scuba diving deco as it is how they behave which determines how long we decompress and can effect our scubadive plan.
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Buhlmann, Computers, and Helium and what it means in scuba diving December 16, 2005

Posted by Andy Carroll in : Decompression , 1 comment so far

This is a bit of a geeky article on deco and gasses and scuba diving decompression models. I wrote it a back in July 2004, when I was initially getting into deeper diving using mixed gasses and starting to do scuba dives which required decompression. I thought it might be useful to some people doing the same and I just fancied getting a bit geeky, as you do.

Disclaimer: Like you, I am continually learning about deco and technical diving. These posts are written primarily to ensure that I have understood what I have learnt and hopefully to encourage others to explore this fascinating subject. I do not guarantee this is correct and I do not recommend you do anything without knowing why you are doing it. I am not responsible if you read anything I write and change your plans and get bent. I am not responsible if your buddy or anyone you know gets bent, and I am not responsible should your dog be run over by a car or because you find a fingernail in your Big Mac. You make your own choices.
Just wanted to make that clear.

What I am discussing today is the decompression model that most scuba diving computers are based on and why we, as technical divers, are beginning to question these models.
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