Life as a Saturation Diver John Osborne

Thank you to John Osborne for coming to see Aquamarine Medicals for his HSE Diving Medical and writing this blog for us. John talks about one of the world’s most hazardous jobs which is known for its intense pressure!

Making a conscious decision to pursue a progressive career choice as a commercial diver, and becoming a saturation diver, can be a leap of faith. Literally! I should warn you in advance, I will digress on the odd occasion.

An aspiring saturation diver must dive a minimum number of hours at a variety of depths within the air range (0-50M). Once the diver has achieved the pre-requisites, he/she then has the ‘minor’ hurdle of paying for and attending a course and then joining other new saturation divers in the pursuit of that first ‘lock out’!

There’s an element of good fortune and timing involved in being in the right place at the right time to get into saturation diving. Upon getting the ‘first sat’, the new sat diver will be exposed to a whole different world, literally…!

Prior to entering saturation, the divers receive a pre-dive medical by the vessel medic and will sign to certify they are fit and happy to commit to exposure to saturation. Signing the pre-saturation medical forms, the diver takes responsibility for his health and fitness to dive, and that he is not carrying any injuries or bugs into system at the start of the trip. Once the divers are in the system and saturated, then they can’t pop out to visit the medic, they are confined behind a pressure hull and return to surface/atmosphere is determined in days/hours depending on the depth of the project.

Once medicals and project briefs are completed, the last group of humans the divers will interact with are the crew in Life Support. The Life Support department: normally a Life Support Supervisor, Life Support Technician and 1 or 2 Assistant Life Support Technicians. They quite literally monitor the divers within the system 24 hours a day until dive operations, decompression schedules and bend watch are completed. This includes diver welfare, feeding and watering, dive and personal laundry, provision of all dive equipment to sustain operations, communications and monitoring the environment in the chambers. The Life Support department are vital in the success of any dive operation involving saturation exposures.

Forget about the diving for now, just life and living within the confines of the saturation system itself can be extremely daunting to the uninitiated on arrival.

If we use the example of a team of 3 divers, they will be on shift for 12 hours and on rest period for 12 hours, 0600-1800 day shift with 3 other teams to ensure 24 hour coverage to the project. The maximum the divers would expect to be committed and confined to saturation would be 28 days.

'Silver service!'

This shift would see the team shaken (woken up) at 0600, breakfast delivered via the med lock and the day begins

Med lock (nearest) and equipment lock (furthest away)

There are two locks of interest, the medical lock and the equipment lock. Med lock is within the main living chamber and items are sent in and sent out of the sat system via this means.

View into wet pot and chamber from equ. lock

The equipment lock is within the Wet Pot (a smaller chamber that contains, amongst other things, a toilet, sink, plumbing for shower, access hatches/doors to remainder of system and the equipment lock).

Equipment lock from outside

The equipment lock is mainly used to send divers hot water suits, dive underclothes, water, soda-sorbs and larger items for the dive bell, such as a Kirby Morgan Surface Supplied Diving Equipment (KMB SSDE) dive hat.


Back to the dive team on shift. At around 0630, their dive gear will be locked in and they get dressed in to undersuits to standby for the day ahead. At around 0700, the Bellman (more later) will enter the Dive Bell from the Wet pot and conduct Bell checks under with the shift Dive Supervisor. They are known as Bell checks and it involves the Bellman setting the Bell up for diving operations and ensuring the bell can and will deploy as directed by the Dive Supervisor. The Bell is lowered from the sat system where the divers live on board ship under pressure, to the depth where the underwater work is that needs to be done.

The pressure in the Bell is initially at the same pressure as that in the saturation chambers but as working depth is reached, the pressure is increased to working pressure and the Bell hatch is opened. The divers will operate as Diver 1 and Diver 2 deploying from the dive bell to conduct the work scope as briefed by the supervisor. The third diver will be the Bellman, in effect the standby diver, poised and prepared to lock out of the Bell if the situation requires it.

When the Dive bell ‘locks off’ the system for dive operations, it will be expected to be off the system for a maximum of 8 hours, with the divers leaving the Bell for a maximum of 6 hours within that 8 hours. The divers are each tethered to the Bell by an umbilical which provides breathing gas, light, comms and hot water for their suits.

The diving operations conducted in saturation diving are in effect same as for air diving…diving tasks/projects are after all subsea, the key difference is the gas medium being breathed and the length of the diver’s commitment to saturation and then the length of the decompression, nominally a single decompression at the end of a project. It can be quicker to return from space than it is from saturation.

Top left: External view of chamber and adjoining trunking to left. Top right: Trunking between chambers and up to bell on left. Bottom left: Trunking entering bell hangar (bell off the hub trunking) Bottom right: Trunking to dive bell

At the end of the dive, the divers return to the Bell, which is then lifted back up to the ship and mated onto the saturation chambers at ‘storage’ depth. Once the divers return to the sat system post diving, they will lock out all dive clothing and any equipment requiring reserviced. Life Support will feed, water and service the team and all post dive reports/concerns will be addressed.

Sleeping area

Once the divers settle into off shift routine, they can relax (within reason) in traditional manner, read, watch tv, even converse with one another, albeit with squeaky voices due to helium mix. Then its lights off, and rest.


Above is a very scant outline of a routine day, without trying to divert to talking about diving. Life in the sat system takes a fair bit of getting used to and rightly so. It’s quite alien to everyone and takes some getting used to. The best analogy I can use is, it’s like going from a school disco to the first outing in a night club, no idea where anything is, and not sure if you should out your lack of knowledge by asking ‘all the obvious questions’!

Surviving in saturation, a team relies on one another, physically and socially. It’s vital they can rely on each other. A small matter on the surface, can be a huge concern stored at 100M.

Diver personal health and wellbeing must be of a high standard to sustain being effective over a potential 28 saturation exposure. Most, if not all divers within saturation system, will hold Diver Medic Technician certificates and can to some degree administer themselves for small medical concerns. In the event there is an issue, such as an ear infection, (small matter on the surface, not in saturation) it is better the diver speaks to the medic early and is issued ear drops. To ignore the ‘itch’ then develop a worse infection, could result in the infection spreading throughout the system and the whole team being unfit to dive, which would not go down well. Especially if it could have been avoided.

Mental wellbeing, it goes without saying is quite important. Being confined within a large, pressurised container for up to a month, with no exposure to sun, moon, wind, rain isn’t normal, so it wouldn’t be unreasonable to find that living in a saturation system isn’t for everyone. Who would want to be actually living under pressure, with potential for illness, injury or news from home of a compassionate nature knowing it will take days to get back on ‘the surface’? It’s very unique place to live, function and survive, which thankfully doesn’t get taken for granted by those who work within (and support) the restrictions imposed."

'A day in the life of a Saturation Diver'