Often spoken of as the ‘holy grail’ of commercial diving. Any diving over the depth of 50 metres is the domain of saturation divers; Highly paid and deep sea divers.
The likelihood of oxygen toxicity and narcosis increases for ordinary air divers at this level of pressure making operations using air a limitation for them.
The use of mixed gases that are inert enough to be safe to breathe, while maintaining an oxygen supply is necessary.
Using a blend of Helium and Oxygen saturation divers aka SAT Divers can reach levels of diving exceeding 300 metres. This blend is commonly called Heliox, a mix of oxygen and helium. It’s only drawback is the squeaky voice is causes and that it can chill a divers body somewhat.
Training starts typically after a 3 – 4 week course at an IMCA dive school. This course is even more expensive than the Commercial Air Diving Course and is quite challenging.
Sat Diving Operations take place at sea on board Dive Support Vessels.The Saturation System is in three parts. The Rest Area, the Transfer Chamber and the Dry Bell itself. This system can be lifted using a crane to and fro vessels and the mainland as a complete unit. Making it a versatile package.
The divers and all three areas of the SAT system are pressurized down to the depth they will be working from. The divers who are required to go on-shift are then lowered down to the job in a Dry Bell. The gases for breathing off are supplied from large cylinders attached to the Control Room in the DSV that have an umbilical cable attached to the Dry Bell that the divers breath off. Spare breathing gas is attached to the Dry Bell if the umbilical should somehow be cut, damaged or fail to supply gas. The Bell is lifted and re-joined to the Transfer Chamber when it is time for the other shift to take over.
Hot water suits are worn for saturation diving; the hot water being pumped down from boilers on board the DSV to the Dry Bell.
When the time comes for the divers to be decompressed this is done at a very gradual rate of about 15 metres per day. In the 70s and 80s the decompression models were more aggressive than this and nowadays the models are more safe for divers. Nevertheless the story’s of bone necrosis associated with SAT diving is still bandied around commercial dive circles. This is considered a less-likely long-term risk with the new decompression models…
It is advisable to commercial divers out there to make sure you have enough experience before taking the plunge. The money SAT divers are on might be pop star wages but commercial Dive Schools are churning out Sat Divers like they are going out of fashion these days and there’s only so many jobs…
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