Is there any advantages of using AIR for Deco?

[Don Burke]

If you read all of Jean Eve's threads it becomes quite clear that he's been having some problems with DCS due to his work - and is trying to find the best solution to the problem - IN TAHITI.

A chamber ride is the best solution to the problem. It may take several rides.

In-water recompression on air may be even more dangerous than dealing with the DCS.

 

[Mako Mark]

In-water recompression on air may be even more dangerous than dealing with the DCS.

or a home made chamber........

What I have noticed from seeing commercial diving operations in developing nations (Honduras, Nicaragua, Fiji, SE Asia, Mexico) is that the commercial divers are often treated as disposible people.

They get into it for the money as that is high compared to subsistance farming or regular fishing, and the Developed worlds demand for lobster tail can afford to offer them the "big bucks". The divers often have little or no formal education particularly diving related, have no idea of the risks involved, or no option other than to accept those risks or live in poverty.

Now I am not saying that this is the case in Tahiti, I highly doubt from Jean Eves intelligent posts that they are in the same league as the Phillipino long hose fishermen as far as the low price of human life, but I am sure that the level of acceptable attrition in the pearl industry is far higher than would be acceptable in the north sea oil fields for example.

The fact that they are doing deco dives on a daily basis on an atoll with no chamber kind of proves this.

A point in case for Mexico was that until recently, before the availability of hydro testing for tanks, when tanks were so out of test that tourists stated to question their security, they were sold to the lobster fishermen who use them until they leak too much from the neck to be of any value.

What is seen as acceptable practice in one situation is deemed unacceptable in another...

That is why I like Jean Eve's posts. However innocent of the DIR "written in stone" mandates and present North America tec diving dogma Jean Eve is, the fact is that he/she is doing this kind of diving on a daily basis anyway.

It puts the dogma in perspective.

.

 

[Jean eve]

Everytime I posted a question,there is always negative or possitive answer.But cancun Mark is a more understanding person and I always get good information from him.
Over here(Tahiti),We'd been using AIR for Decompression quite long ago.Tahiti do have a mix station(I mean dive club-but not all)but not in all the pearl farm.

Originally posted by Don BurkeYou got there. Your dive gear got there. The oxygen for emergencies got there. A cylinder of oxygen for mixing can get there.

Since a mix gas station a quite expensive,If we can mix the air with O2 without using the mix air station.(HOW??)Of course then it is better than using mix air!

Perhaps we should be asking Jean Eve as to why they are NOT using nitrox to deco?Is it economic?
Is it logistical?
Is it lack of knowlege or training?

My question for Jean Eve, is what kind of profiles are you doing?

My knowlege of mussel farms in NZ is that shelfish are grown pretty close to the surface, so I would think that a pearl farm would be shallow too. So unless you are doing five hour dives, you should be able to plan no deco dives, or am I way off base here?

I don't know why the goverment don't provide Nitrox classes for pearl farm diver.But what I think is:
1.Not common and not economical-Pearl cultures in Tahiti start long time ago,years now.That time Nitrox is not so common yet,but what curt bowen said he is been using O2 for 14 years(I'm sure that time it is very rare for diver using O2 for Deco).So they made a decompressed table specially for the diver here using air.(Heard that they are going to start Nitrox for pearl farm diver)A mix air station is quite expensive and it is hard for a 'small' pearl farm to have it!(only some are big pearl farm)
2.The dive was not deep-Though there is diver went down to 60m and used AIR for Deco but it is very rare.Most of the pearl farm working depth range from as shallow as 10m till 50m.(each pearl farm is not same.It is themself to see what is the best depth for the oyster and the pearl.)Mostly,the depth was between 10m-20m.
3.Dive time was not long-The dive time for most of the pearl farm was not long,and usually need few min to decompress.
Unfortunately,my working method of my pearl farm was not same due to the sea environement.(lack of food for the oyster)So we have to work for longer time at the bottom.(so we do Deco longer than other pearl farm)We'd been looking ways to improve diving in our pearl farm but we can't just using Nitrox like this because they only allow AIR to be use.

Originally posted by KimLeece
I believe that the pearl farming comes from the fact that the original poster has made many references to it in other threads - so it's fair to assume that he has something to do with it! If you read all of Jean Eve's threads it becomes quite clear that he's been having some problems with DCS due to his work - and is trying to find the best solution to the problem - IN TAHITI.

Actually is not all in TAHITI,but I think only my pearl farm.There is many accidents in other pearl farm,but I think the main reason is they don't stick to the 'rules'.
In fact,untill now I still don't have any DCS/DCI nor the divers in my farm.But I'm just looking some solution to prevent it and make the divers more safety.Eveybody know that it is no good to do vigorous exercise down there when you are diving,but we can't avoid this in a pearl farm-exspecially mine!
Imagine trying to pull down a 15kg buoy down to 15-20m with a rope(Secure your self on the rope to tie the osyster and pull down the buoy with a rope),sometimes we have to pull down 10-30 buoy.It's hard already for us to pull up a thing weight 15kg on the land.
Other pearl farm have free diver to pull down the buoy.But not ours(The skin diver are very strong,I'd seen one pulled down a 15kg buoyancy buoy down to 12m 'without' using FINS!)

It can still be used to inflate the tires to bring you to the divesite (but even there are gases are better

If AIR only have disadvantages except inflate your tires then I will not be here posting my tread!(Die of DCS/DCI )

Originally posted by curt bowen
Before it was ever available in the dive shops we mixed in our garages.

Maybe I should learn it!(how to mixed it without using mix air statio?)

Just want to know what is the Advantages and disadvantages of AIR.
Thanks.

 

[Mako Mark]

Jean Eve,

A nitrox blending station can actually be very cheap, particularly when you use the partial pressure blending technique.

You would need to have some O2 clean tanks, some filters and a filling whip, and training on how to blend safely. A partial pressure blending whip can cost as little as $200 USD. The most important thing about this type of blending is the problems with fire and explosion, that is why you need O2 clean tanks etc.

One other option is have a 15 ft/5 m long hose from a bottle of pure O2 on the boat. This would depend on the size of you boat though, but it would eliminate the need for blending, and allow you to do the last stop, or safety stop with the advantages of O2.

Remember though, wherever you have O2 you have a fire risk so make sure you know what you are doing before you try this.

 

[Don Burke]

Since a mix gas station a quite expensive,If we can mix the air with O2 without using the mix air station.(HOW??)Of course then it is better than using mix air!.

Mixing nitrox is pretty simple and the whip and gauge you need is not all that expensive.

I don't know why the goverment don't provide Nitrox classes for pearl farm diver.

You may not need them. The requirement for nitrox certification is not law in the US and I suspect it is not there either. Considering some of the people I have seen blending nitrox, I expect you would have no trouble with a little training.

But what I think is:
1.Not common and not economical-Pearl cultures in Tahiti start long time ago,years now.That time Nitrox is not so common yet,but what curt bowen said he is been using O2 for 14 years(I'm sure that time it is very rare for diver using O2 for Deco).So they made a decompressed table specially for the diver here using air.

I still have several air decompression tables. They just are not the best way to go.

(Heard that they are going to start Nitrox for pearl farm diver)A mix air station is quite expensive and it is hard for a 'small' pearl farm to have it!(only some are big pearl farm)

It is sounding like the whip system Mark is talking about would be the best way to go. It would avoid many problems.

2.The dive was not deep-Though there is diver went down to 60m and used AIR for Deco but it is very rare.

60 meters on air is pretty dangerous in itself. Doing the deco on it is as bad or worse.

Most of the pearl farm working depth range from as shallow as 10m till 50m.(each pearl farm is not same.It is themself to see what is the best depth for the oyster and the pearl.)Mostly,the depth was between 10m-20m.

That is a good range for nitrox.

3.Dive time was not long-The dive time for most of the pearl farm was not long,and usually need few min to decompress.

The oxygen would be great for that.

Unfortunately,my working method of my pearl farm was not same due to the sea environement.(lack of food for the oyster)So we have to work for longer time at the bottom.(so we do Deco longer than other pearl farm)We'd been looking ways to improve diving in our pearl farm but we can't just using Nitrox like this because they only allow AIR to be use.

Who is allowing air only? Is it the government or just the management of the other farms?

Actually is not all in TAHITI,but I think only my pearl farm.There is many accidents in other pearl farm,but I think the main reason is they don't stick to the 'rules'.
In fact,untill now I still don't have any DCS/DCI nor the divers in my farm.But I'm just looking some solution to prevent it and make the divers more safety.Eveybody know that it is no good to do vigorous exercise down there when you are diving,but we can't avoid this in a pearl farm-exspecially mine!
Imagine trying to pull down a 15kg buoy down to 15-20m with a rope(Secure your self on the rope to tie the osyster and pull down the buoy with a rope),sometimes we have to pull down 10-30 buoy.It's hard already for us to pull up a thing weight 15kg on the land.
Other pearl farm have free diver to pull down the buoy.But not ours(The skin diver are very strong,I'd seen one pulled down a 15kg buoyancy buoy down to 12m 'without' using FINS!)

Is there any chance of hooking a rope to the thing on the bottom and hauling it from the surface. Getting rid of that exertion underwater will help avoid DCS.

Maybe I should learn it!(how to mixed it without using mix air statio?)

I am sure we can scrounge up a book to send you.

Just want to know what is the Advantages and disadvantages of AIR.
Thanks.

The only advantage of air is that you have it. Talking about other gasses is just an academic exercise unless you can get them.

 

[Snowbear]

Is there any chance of hooking a rope to the thing on the bottom and hauling it from the surface. Getting rid of that exertion underwater will help avoid DCS...

I don't know anything about oyster farming, but I'm assuming it's some kind of basket or pot being hauled up? How about taking down an empty lift bag and inflating it at depth? That would eliminate most of the effort?

 

[Jean eve]

Originally posted by Cacun Mark
What I have noticed from seeing commercial diving operations in developing nations (Honduras, Nicaragua, Fiji, SE Asia, Mexico) is that the commercial divers are often treated as disposible people.......................

Actually the law over here for pearl farm diver are quite strict.For example,If there is any diver died while diving in your farm,then you have to closed your farm.
We are lucky enough in Tahiti as we do have formal training and education(but not as high as a pro).To work as a pearl farm diver,one have to go for a special course for at least 6 weeks or 12weeks even if your are holding an instructor license you still need to go for the course,because it is totally difference from recreational diving.
There is so many atoll in Tahiti(more than hundred),and all the pearl farm are in the atoll.Due to the expensive cost of a chamber,the goverment here can't set up so many chamber in the atoll so they only have two chamber available here(Tahiti-mainland)If one have to go to the chamber,it takes from an hour to few hours,depand on which atoll you are staying.

Originally posted by don burke
Is there any chance of hooking a rope to the thing on the bottom and hauling it from the surface. Getting rid of that exertion underwater will help avoid DCS.

Originally posted by snowbear
I don't know anything about oyster farming, but I'm assuming it's some kind of basket or pot being hauled up? How about taking down an empty lift bag and inflating it at depth? That would eliminate most of the effort?

In fact like this kind of working(pull down the buoy),the goverment also not encourage it.We'd also try the method above,inflating a lift bag at depth to bring down the buoy.But it is hard for the work to advance.Because of we can't find any method better than this,So I'm looking another way to minimize the chances to get DCS/DCI.
There is an attach about oyster farming.

Originally posted by don burke
Who is allowing air only? Is it the government or just the management of the other farms

The goverment(France) allow air only for pearl farming.

Originally posted by cacun mark/B]
A nitrox blending station can actually be very cheap, particularly when you use the partial pressure blending technique.

You would need to have some O2 clean tanks, some filters and a filling whip, and training on how to blend safely. A partial pressure blending whip can cost as little as $200 USD. The most important thing about this type of blending is the problems with fire and explosion, that is why you need O2 clean tanks etc.

Since the cost for this is cheap,I think this is a good idea!But....What is actually a partial pressure blending whip?


Very glad I can get all this information from all the pro.
But from all the question I asked,It seems like I'm a 'cave man'.

 

[Don Burke]

Since the cost for this is cheap,I think this is a good idea!But....What is actually a partial pressure blending whip?

Partial pressure nitrox blending is where oxygen is put in a scuba cylinder to a specified pressure and then the scuba cylinder is filled the rest of the way with air. The danger point is that pure oxygen is being handled, which is why the scuba cylinder needs to be oxygen clean. When the air is first being put in, the scuba cylinder contains nearly pure oxygen, so the air needs to be especially clean, which is what the filters are for.

In response to your question, the whip is a hose with connectors for the oxygen tank and the scuba cylinder, a pressure gauge and a bleedoff valve. All of this needs to be oxygen clean.

For reference, a 3000psi tank drained to zero, filled with oxygen to 418 psig and then topped with air to 3000psig will contain EAN32, which is good to 33 meters before the oxygen partial pressure gets to 1.4 ATA. That will let you dive to 20 meters on a 15 meter table.

Is doing this going to get you in trouble with the government?

Would hanging the 5 meter lines with regulators over the side with pure oxygen work for you?

Very glad I can get all this information from all the pro.
But from all the question I asked,It seems like I'm a 'cave man'.

You are doing what you can with what you have.

 

[teknitroxdiver]

It would be better than bottom mix.....

 

[miketsp]

I had posted this link on another thread started by Jean Eve. It gives some background into Australian practices - interesting to see the low accident rates considering the high number of deco dives.
But there they use a lot of O2 for deco stops and very slow ascent rates.

http://www.fish.wa.gov.au/res/broc/frr/frr138/frr138.pdf