A saturation campaign is planned months before anyone gets into the chamber. The process chains together scoping, task engineering, gas and consumables calculations, crewing of divers and support staff, vessel contracting, permits and risk assessment, and a realistic weather window. Each link constrains the ones that follow.
The visible part of saturation diving is the bell going down the side of the vessel. The part that decides whether the job goes well happens much earlier, in offices, with spreadsheets, asset drawings and a calendar. A saturation campaign is a complex logistical operation involving a vessel, a life-support system running under pressure, a large crew, expensive industrial gases and a sea window that nobody controls.
This article walks through the planning in the order it's usually done, from the client's first enquiry to the team's demobilisation. It isn't an official procedure: it's the skeleton most projects share, useful above all if you're coming into the trade and want to understand why your campaign is organised the way it is.
1. The scope: exactly what needs doing
It all starts with a request from the client — a field operator, an infrastructure owner, an engineering firm — describing an underwater problem. It might be a scheduled inspection, the repair of a damaged component, a pipeline connection or the decommissioning of a structure.
The contractor's first job is to turn that description into a closed scope. That means answering precisely questions the client sometimes hasn't worked out:
- What the asset is and what state it's in. As-built drawings, previous inspection reports, repair history. A twenty-year-old drawing and a structure covered in marine growth don't describe the same thing.
- At what depth and over what range. The nominal depth isn't enough: what matters is the shallowest and deepest point of the task, because the storage depth comes from that.
- What needs to be worked on, and with what. Cutting, welding, bolting, replacing parts, installing components. Each of those brings its own tools, consumables and required competence.
- What counts as finished work. Acceptance criteria, testing, photographic or video record, report.
This first block produces two documents that govern everything else: the scope of work and a preliminary duration estimate. If the scope is poorly closed off here, the error compounds through every later phase.
2. Task engineering and method of work
With the scope defined, the technical team decides how the job gets done. This phase produces the work procedures: the sequence of operations, the tools, any jigs to be fabricated, the lifting arrangements, the mooring points and the split of tasks between divers.
This is where decisions that shape the whole campaign get made. If the task needs a custom-fabricated part, it has to be ordered ahead of time and tested at the surface before it's shipped out. If it needs hyperbaric welding, a habitat has to be brought along, the procedure qualified, and welders certified for that specific procedure secured. If thick steel needs cutting, a choice has to be made between oxy-arc cutting and mechanical means, with the consumable planned for.
It's also decided here whether the task is done with divers, with an ROV, or both. On many modern projects the ROV handles the prior inspection and monitoring, and the diver goes in only where fine manipulation is needed. That split is defined at the engineering stage, not improvised on board.
3. Storage depth and campaign profile
The decision most characteristic of saturation diving is what pressure the divers will live at. The storage depth is chosen so that every work point can be reached by excursion — moving up and down from the bell within set limits — without needing to recompress or decompress the system halfway through the project.
If the task spans a wide range of depths, this forces a compromise: too shallow a storage depth puts the deepest points out of reach; too deep unnecessarily lengthens the final decompression and pushes up the gas cost. When the range can't be covered in one go, two phases are planned with an intermediate decompression, which changes the whole schedule.
The chosen profile produces two key numbers: the planned bottom days and the days of final decompression, which don't depend on how long has been spent in saturation but on the storage depth, and which have to be reserved in the vessel's schedule as unproductive but mandatory time.
4. Gas, consumables and logistics
The gas calculation is an arithmetic exercise with expensive consequences. The helium and oxygen needed have to be estimated for pressurising the system, for the divers' breathing consumption over the whole campaign, for normal operational losses, and for a reserve margin that allows contingencies to be dealt with without aborting.
The result determines how many gas quad racks the vessel loads, whether a mid-campaign port resupply has to be planned, and whether it's worth installing or using a helium recoverysystem. On long, deep projects, recovering helium stops being an environmental option and becomes an economic necessity.
Alongside the gas comes everything else: soda lime for CO₂ scrubbing, water, food for the whole crew for weeks, critical spares for the saturation system, spare umbilicals, thermal underwear, cutting and welding consumables. The consumables list is finalised early because the vessel has finite capacity and because resupplying mid-campaign offshore is expensive and weather-dependent.
5. Vessel and system
El dive support vessel is normally the most expensive and least flexible part of the equation. Its availability sets the dates: if the right DSV is booked out until October, the campaign happens in October however much the client would have preferred August.
Vessel selection weighs several criteria: the capacity of the onboard saturation system — maximum depth and number of divers it can house — dynamic positioning class, crane capacity, free deck space for the project's equipment, endurance and suitability for the sea state of the area. Logistics count too: a great vessel sitting on the other side of the world comes with a mobilisation cost that can throw the budget off balance.
Before mobilising, audits of the saturation system and checks of the equipment's certification are carried out. A system with expired certificates doesn't go out to work.
6. Crewing: who's on board
A saturation campaign isn't run by the divers alone. The typical crew combines several roles working shifts that cover twenty-four hours a day:
- Saturation divers, organised into teams who rotate through the bell. The number depends on the volume of work and on chamber capacity.
- Diving supervisors, who direct every dive and sign off on operational decisions.
- Life support technicians, responsible for keeping the atmosphere and conditions of the system in order.
- System and maintenance technicians, for compressors, hot water heaters, LARS and the gas panel.
- Surface personnel: crane operators, riggers, deck crew, ROV team, and the vessel's own crew.
- Personal sanitario: at least one diver medic available, with access to specialist medical advice.
Personnel planning checks more than just names: it verifies that each person has current certification, a valid medical, up-to-date survival training and the specific experience the client requires for that project. A diver with an expired medical certificate doesn't go on board, and replacing them at the last minute is a serious problem.
7. Permits, risk assessment and documentation
Before starting, the operation goes through a body of documentation the industry has built up over decades of accidents. The usual elements are:
- Risk assessment and HAZID/HAZOP for the project, with input from the people who are going to carry it out.
- Permits to work and isolations: guaranteeing that nothing in the system the diver is going to put his hands into can start up, pressurise or suck while he's in there.
- Emergency plan: medical evacuation from saturation, hyperbaric rescue, fire, loss of vessel position, gas supply failure.
- Bridging document, which reconciles the client's procedures, the vessel's and the diving contractor's where they differ.
The industry's codes of practice, in particular those published by IMCA, and the regulations of the country where the work takes place set a good part of these requirements. In waters with a strong regulator, the documentation gets audited.
8. The weather window
The final schedule isn't built from working days alone. It's built from working days plus weather contingency days. Every area has its own statistics: the North Sea is workable almost year-round but with hard winters, and other areas have a monsoon or cyclone season that shuts the window outright.
Planning draws on historical wave-height and wind data to estimate what percentage of the time the operation will stay within limits. That's where the buffer comes from. A project with twelve days of effective work may need the vessel booked for twenty if the area's statistics call for it.
There's one quirk worth understanding: bad weather doesn't interrupt saturation. The divers carry on living under pressure while everyone waits, with the associated cost, which is why the weather feeds straight into the budget.
9. Mobilisation, execution and demobilisation
Mobilisation is the phase where everything that's been planned gets loaded onto the vessel: system, equipment, gas, consumables and personnel. The saturation system's functional tests are run, umbilicals are checked, communications are verified and emergency drills are held. Projects that skip this phase in a hurry pay for it within three days.
During execution, planning doesn't disappear: it turns into the daily operations meeting, where progress, the weather forecast, the state of the system and the next shift's work are reviewed. Any change of scope goes through formal change control.
Demobilisation closes the cycle: final decompression, handover of the technical report to the client, return of the equipment, offloading the system and, for the divers, the start of their time at home before the next rotation.
What this means if you're starting out
For a young diver, understanding the planning has practical value. It explains why dates change, why the supervisor insists on the written procedure, why there's so much paperwork before anyone touches the water, and why nobody improvises a new task halfway through a campaign.
It also explains what makes a diver with years on board valuable: he doesn't just know how to do the job, he understands the system around him, anticipates what's going to be needed, and spots when the plan and reality have started to drift apart. That's exactly the step that separates the diver from the supervisor, and the path to it starts on day one, by paying attention to how what happens around you gets organised.
If you're weighing up entering the industry, the starting point is still training: check how a commercial diver is trained, the map of schools and what certifications each market requires.
Frequently asked questions
How long does it take to plan a saturation campaign?
It depends on the scope. A small intervention on a known asset can be prepared in weeks. A subsea construction project with a chartered vessel, its own engineering and custom-built tooling is planned months ahead, because vessel availability and equipment fabrication are the usual bottlenecks.
Who decides the storage depth?
The planning team sets it from the range of working depths. A chamber living pressure is chosen that allows every point of the task to be reached by excursion within the permitted limits, avoiding the need to compress or decompress halfway through the campaign.
Why does helium shape the planning so much?
Because it's expensive, isn't always available at the port that suits the job, and its consumption depends on depth, number of divers and duration. The gas calculation, with its reserve margin, is done early because it determines the onboard storage volume and the supply logistics.
What happens if the weather turns mid-campaign?
The system doesn't decompress for bad weather. The divers stay in saturation while the vessel holds position or seeks shelter, and diving resumes once sea state is back within operating limits. That's why campaigns are planned with weather contingency days.
Is the planning done by the client or the diving contractor?
Both. The client defines the scope, hands over the asset information and sets the requirements. The diving contractor develops the method, procedures, risk assessment and crewing, and submits them for approval before mobilising.
Can the scope change once the campaign has started?
It can, but it goes through formal change control: reviewing the risk assessment, checking that the gas, consumables and remaining saturation time allow for it, and getting client approval. Tasks added without that filter are one of the classic routes to an accident.
Published 2 September 2026 · By Arthur More, professional saturation diver
Photo: Pimlico Badger · CC BY-SA via Openverse
This article is part of our in-depth guide to saturation Diving in Roblox vs the real thing — the complete picture, with sources.
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