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Topic 67: Discuss the safety aspects associated with using divers in offshore operations

Catriona Ogg's picture

 Using divers in offshore operations carries significant risks.  The environment presents a number of hazards such as poor lighting, restricted oxygen supply and sometimes extreme temperatures or pressures.  Discuss these risks and the safety measures in place to help reduce them.  


Catriona Ogg's picture

The HSE supplies the Diving at Work Regulations 1997, which provides guidelines for safe practice when operators choose to use divers. It outlines a number of requirements for both the diving contractor and the diving supervisor. Some of these have been listed:

Duties of diving contractor 

- Ensure that a 'diving project plan' is in place before the operations begin.  This is a document which outlines the work to be carried out by the diver, an evaluation of the risks involved and the code of practise to be used.  It will also appoint the diving supervisor.
- Ensure that the person appointed to carry out the diving is competent and complies with regulations 
- Keep all record cards of the diving operation for two years

Duties of the diving supervisor

- Ensuring all involved in the project are aware of the contents of the diving project plan
- Oversees operations and ensures that all involved comply with regulations 
- Keeping the diving record card updated

Joan.C.Isichei's picture

Commercial Diving is an extremely risky job especially in the offshore oil industry where diving operations  may run round the clock.  Just in September this year, a diver narrowly escaped death after his umbilical line snapped and his air supply ran out at a depth of 260ft in the freezing north sea[1]. Unfortunately, the same cannot be said for others who have succumbed to diving fatalities. However, like Catriona mentioned in her post, the HSE has several regulations that proffer guidelines to govern diving operations, one of which lists out the duties of a diving supervisor.  Now, taking a look at offshore diving statistics in figure 1[2], It is interesting to note that the number of accidents related to poor/inadequate supervision remains the highest cause of diving deaths. This simply implies that the supervisor duties in Catriona’s post are commonly flouted. Therefore, I feel this calls for the issue of accountancy; a diving auditing body should be set up to monitor offshore diving activities and to ensure that all HSE rules and guidelines are followed religiously, and any company found breaking the rules should be penalized accordingly. 

North Sea Diving Fatalities 1971 to 2001 Distribution of Cause 





Joan.C.Isichei's picture

My apologies for the picture. I don't know why it's not showing. Please find the image in the following link;

Derek Porter.'s picture

I agree with Joan about the need for a diving auditing body as I cannot seem to access a relevant body online. The only body available is one that acts in the case when a diver is killed. This body is named North Sea Divers Alliance (NSDA) and will pursue compensation (Ref 1). Does the HSE do enough to monitor the operations??

Furthermore I would like to mention the case of the Byford dolphin in the North Sea. This involved a horrific accident when a chamber explosively decompressed from 9 to 1 atmosphere (Ref 2). A video of a similar accident that was avoided can be seen in Ref 3. In this example the employees operating were deemed to be at fault. It was later uncovered (by NSDA) to be the fault of the equipment and a pay-out was given to the victims families' (Ref 4).

Ref 1 -
Ref 2 -
Ref 3 -
Ref 4 -

Ahmed_Abdelkhalek's picture

Interesting statistics Joan,

I agree that supervisors are to
be blamed for poor supervision. However, the statistics also show that
poor/inadequate equipment design is a major cause for diving fatalities. This
points fingers to other major contributors to diving fatalities; the diving
equipment manufacturers and equipment certification bodies.

According to HSE’s Diving at Work
Regulations 1997 all diving equipment need to be initially certified. If proper
certification procedures are applied they would automatically screen out
equipment that is poorly designed.

The divers
and supervisors are end users who blindly rely on the ‘Certificate’ of the
equipment to ensure that it is safe to use.

Etienne Gunter's picture

There exists an organisation that audits diving schools and their practices. It is called IMCA - The International Marine Contractors Association [1]. Each country has their own diving regulations that have to adhere to organisations similar to the HSE. IMCA evaluates these companies and tries to set a standard that is internationally acceptable. Therefore companies become members and are then accredited.

Even still, standards are not the same throughout industry. Diving schools only meet ends if they have enough students that pass. And on a rig you can have numerous divers from all over the world, trained to various levels. I agree that it is up to the supervisor to make the call, but again, there is a lot of pressure on him to get the tasks done.

In the end, it is up to training, professionalism and regulation. No machine will ever completely replace humans.


Oluwatosin A. Oyebade's picture

Reverting back to the topicof discussion, diving operation is a major challenge that should not be handled with levity. Several riks are associated with diving and logical examples are highlighted in this discussion. During diving operation, the diver is exposed to a water filled environment so the possibility of water inhalation cannot be ruled out. The consequence of inhaling water is suffocation due to drowning which could  lead to death. A way of preventing this is the use of masks that cover the entire face of the diver. Masks equipped with voice communication are as well needed so as to give the diver an avenue to signal emergency situations.

Another important risk during diving operations is the loss of air supply to the diver. Just  as catriona pointed out, poor lighting of the diving environment may not alert the diver of the possible disruption to the flow of oxygen from the breathing equipment. Also there is the possibility of contamination of the air supply by combustion product (e.g carbon monoxide) from the engine of the breathing equipment. The consequence of both scenarios is the possibility of asphyxiation which could lead to death of the diver. The safety measure to take in order to avoid the risks is to ensure that proper breathing equipment is maintained appropriately and risk assessment is carried out prior to the beginning of the operation so as to prepare for unforeseen circumstances.

A major challenge in the oil and gas industry regarding diving operation is the contribution of human factor. What can be drawn from the image provided by Joan is that the top seven causes of diving accidents can be related to human error. Judging from the statistics presented by this image, the root causes of diving accidents can be presented if the management of diving accidents is well handled. A good barrier that can be put in place to check these causes is the adequate training and routine assessment of personnel involved in diving operations so as to check their level of competency.

Oluwatosin Oyebade

Msc Oil and Gas Engineering

Michail.Sevasteiadis's picture

There are many risks associated with commercial offshore diving which are related with health and safety of the diver. First of all, exposure to notable environmental pressure changes lead to health problems related with the body pressure, injuries or even permanent disability. However, this risk can be reduced when up to date techniques and practices are followed like a study has shown. Other significant risks are the condition of the weather the given time, the quality of the used diving equipment and the type of the work that should be done. A frequent underwater exposure for years may cause from hearing loss till failure to recover from a trauma while a diver may have to deal even with toxic environment. It is expected that with the improvement of the diving procedures, decompression illness will be significantly reduced.

1) The Diving Medical Advisory Committee. Statement on Commercial Diving and Health. October 2006. London.

Uko Bassey's picture

Catriona and Joan have stated some of the requirements necessary for diving operations in the previous comments. Before signing any contract with a diving company, it is mandatory for the client to have a thorough knowledge of the diving operations in order to conduct a proper audit. Both the divers and supervisors in addition to their equipments should be adequately examined with the approved industry standards. Before diving operations is commenced, divers are always kept in a semisubmersible diving vessel called hyperbaric chamber which is required to provide divers with the equivalent pressure and temperature conditions in the applicable water depths. Divers are exposed to several risks ranging from oxygen poisoning, lost of balance and control due to high pressure, accidents and dangers from marine animals, etc. From the origin of offshore oilfield developments to late 1960s, all the underwater operations were always carried out using divers. Lecture from TECHNIP (one of the key players in subsea industry) stated that the highest water depth a diver can go is about 300m and here they tend to behave abnormally because of heavy breathe of oxygen poisoning, nitrogen, helium, etc. ROVs have replaced divers in most key operations which is a great relief to offshore operators because they can do virtually everything that will be required of human divers and has made deep offshore explorations more attractive thanks to technology. 



Catriona Ogg's picture

Interesting statistic, Joan. I'm surprised to see that so many of the recorded deaths were a result of human negligence; I was expecting the main cause to be unforeseen risks and freak accidents.  It would appear that trainee divers are not receiving the adequate training that enables them to operate safety in the diving environment. Perhaps this is caused by the training period being too short or that the material they are supplied with is simply lacking in information.  The supervisors are ultimately to blame as they are responsible for the lives of those whom they are supervising, and I agree that stricter monitoring is perhaps required.

Connie Shellcock's picture

Uko identified that there has been an increase of ROV use
and I would just like to add to this. In a study carried out by Ramnefjell et
al, they point out that that there has been an increased in manpowered diving
instead of ROVs due to the fact that robots lack the ability of precision. This
source also points out that most fatal accidents were caused by failure to
follow safety procedures. This emphasises the importance of safety issues
identified in this blog. If diving is going to be on the increase according to
this source, then safety factors such as supervisor duties as already mentioned
need to be reinforced. (Ramnefjell,
Morild et al. 2012)

M.P., MORILD, I., MØRK, S.J. and LILLENG, P.K., 2012. Fatal diving accidents in
Western Norway 1983–2007. Forensic science international, 223(1–3),
pp. e22-e26.


Foivos Theofilopoulos's picture

I do not claim to be a professional diver, although I have received training on scuba diving. While diving is inherently dangerous, it is almost never the fault of the diver when something happens. Safety is taught in the diving schools and they will be trained for the job they have to do as well. The danger comes when you get or take a risk, to do a job faster, to follow orders of a company because you are scared of getting fired. So if you always just follow the rules, it is safer. Almost all the diving offshore is saturation diving, which is a method used to reduce the chances of decompression sickness. However, saturated diving has a long list of medical problems associated with it, and the long hours the divers are forced to work (12-hour shifts) add up to that a lot. 

Tilak Suresh Kumar's picture

Diving Operations involve a unique combination of occupational
health and safety issues performed in an unforgiving environment where errors
can quickly develop into fatal accidents. Individual risks must be managed if
diving is to be conducted in a safe and efficient manner. There are a variety
of regulations, standards and industry guidelines that apply to Diving. The
IMCA International Code of Practice for Offshore Diving
provides advice on
ways in which diving operations can be carried out safely and efficiently.
Moreover any person wishing to become a professional diver normally requires
specific training that satisfies any regulatory agencies which have local
authority, such as US Occupational Safety and Health Administration,
United Kingdom Health and Safety Executive or South African
Department of Labour. The regulatory bodies have a stringent HSE
practice to ensure the all the diving operations are carried out safely.

Agba A. Imbuo's picture

Connie has made an important statement regarding the use of ROV’s worth noting. In as much as human precision far outweighs that of ROV’s, depth is also an issue in the industry. The use of divers in offshore operation has over the years been on the decline as exploration of oil and gas is moving to deeper waters. What was regarded as deep water in the 60’s is now considered as a shallow water. The approximate depth of North Sea wells is 1800m but divers can only go a maximum 300m. This means going a further depth poses a risk to human life as a result of gas poisoning with reduced depth. I am not totally criticizing Connie’s views on the use of divers in offshore operations but will like to say that it is limited to shallow waters where the risk exposure is low.


Connie Shellcock's picture

I totally agree that the deeper we get the more
dangerous itgets for divers, however I thought I would add this point. I have
just spoken to my friend who is a commercial diver and he said this:

“no matter how good their cameras get it will never
be as good as a diver actually on the job, we get a much better idea of what
the work site looks like and can find possible problems quicker and overcome
them quicker, we can also get in tight spaces and get ourself free if we do get
Obviously as we go deeper they will favour ROVs over diver due to medical
worries for divers but some jobs just can't be done by ROVs.
I'd say divers are more reliable than a robot to and we are relatively cheap
and easy to replace compared to ROVs.”

So maybe the solution for the time being is to look
at advances which can enable humans themselves to go down to deeper depths
rather then at ROV who would do the job of the diver

Ryan Grekowicz's picture

I've met several people who used to be commercial divers but quit because they said it was just too dangerous.  This concerns me because I have several projects (deep and shallow water) which are going to require divers.  Our first strategy for executing the work safely is if at all possible, don't use divers (no offense to the divers out there).  If an ROV can access something, then the ROV should be utilized.  This is an important thing to consider when designing a project.  Even if the piece of equipment is only 75 feet below sea level (I'm referring to equipment on the hull of a semi or SPAR), make it ROV friendly.

If you absolutely have to use divers, the next thing that we do is to conduct detailed audits of the diving contractors to ensure that their equipment is maintained, they have all the required safety equipment, and that they have a good track record in delivering projects.  We also put a couple company representatives on the dive vessel to ensure that all the safety requirements are being adhered to. 

Ber_Mar's picture

Although i haven't worked in Subsea Industry, coming from a diferent industry, i have to say i agree 100%, if proven possible ROV should be used. Althouugh one might estimate the value of a human life, it is priceless. That is why i believe the importance of SubSea simulators to be so big. They allow different parties to test their design in office in order not to have to call a diver unless really needed. By doing this lifes will certainly be saved but a better grasp of problems and improvments needed for ROV will be achieved, leaving divers just for specif works or emergencies.

Richard Milne's picture

I work for on of the diving contractors and we use a combination of both divers and ROV's. As Ryan has stated above, if it is at all possible to use and ROV, then this is by far the preferred route. Again, this is no offence to the divers who do great jobs, but it is generally no big deal if an ROV gets damaged or totally destroyed.

There are 2 different types of diving that are used in general. Air diving, similar to Scuba diving is used down to about 50m and saturation diving, where the divers stay in a Hyperbaric Chamber and breath a mix of Oxygen and Helium, down to roughly 200m in the North Sea. Beyond this, and ROV is used.

Saturation diving is more likely to be used because you get a longer working time from the divers, roughly about 6 hours in the water per diver. Divers will not work 12 hr shifts, this would be too much time for them to be in the cold water.

Divers basically just do what they are told over their communication systems. This in itself introduces some hazards due to mis-communication, or the dive supervisor not being exactly clear on where the diver is around a structure. There are massive risks for divers offshore, and certainly not everyone is cut out for it, but the advances in diving safety over the years have been astronomical and as long as everyone is aware of the risks, then they can be mitigated.

There is no real way that introducing an auditing body, because they cannot be on every vessel at every moment without an extremely large staff, and I honestly can't see any body wanting to take this on, because no companies hurt divers on purpose, same way that no companies hurt their deck crew on purpose, but it can happen through human error and complacency.  

charlesggeorge's picture



Safety is the primary
importance for the drivers who doing job in offshore. According to the health
and safety standards, only professional qualified divers should do the work in
offshore. Divers should maintain good physical condition and health and Environmental
conditions like pressure, temperature of water should be thoroughly evaluated
 carefully for analyzing job hazard. Also each diver is responsible for
knowing own limitations as well as the physical condition and also inform the
diving supervisor immediately when the task or the conditions are beyond the
diver's capability or training. If there is a diving operation going on there should
be a dive team leader who manages the diving and operation of the dive team.
Dive team leader should be experienced all the health and safety procedures and
should have a formal training in dive planning, CPR and also first aid giving experience.


in Oil and Gas Engineering 


Etienne Gunter's picture

If you are qualified as a commercial diver, part of you training will be to administer First Aid in emergencies. This includes CPR. The training for a supervisor is even more intense. The supervisor performs the role as the dive team leader and if he is good, he will know what the capabilities of his divers are.

I include a link form IMCA’s website. It is a document that describes First Aid and other Emergency Drills.  Its focus is quite wide, but I was impressed with the detail and scenarios provided for saturation and air diving. I think the industry has improved quite a bit from the 1970’s and the focus is very much on safety.

Hani Shobaki's picture

As trained commercial diver, certified by the HSE, I have experienced first hand the level of education and skill development required to work offshore. Unlike a recreational diving course which can be completed in only a few days, even the most basic HSE SCUBA Part IV, takes at least two or three weeks to complete. This is only the first course necessary and is the bare minimum qualification for any commercial diver, further to this is would not allow you to work offshore. In order to work as an offshore diver a further 2 months of training would be required, giving the diver a HSE Part II certification.
It is with this intensive training that divers are given the skills to work underwater, learn how to avoid the hazards, and are able to follow the strict procedures of the HSE. It is because of these aspects that commercial diving is actually safer than recreational diving, and while it carries risk it is not as dangerous as many think.
Health and Safety Executive. List of Approved Diving Qualifications. Diving at Work Regulations. 1997. (accessed 01 Dec 2012)

Savitha Haneef's picture

100% agree with the comments saying ROV should be used wherever possible.I cannot agree with Foivos saying following the rule would lead to the safety.Even if the divers follow rules,they are regularly exposed to the dangers of  negative system pressure associated with system equalisation jobs.They are also exposed to the danger of  positive pressure release from a system.Even a very small aperture with an associated pressure profile can cause serious injury should a diver come in contact with it.Similarly, they may be exposed to live electrical or optical containg dangerous levels of laser or electrical energy, this can cause serious injury even without a warning.

Savitha Haneef

MSC Safety & Reliability Engineering

Richard Milne's picture

Hani, it is rather interesting to learn that this much training is required for offshore divers. If anything it goes to prove my previous point that divers are not the ones who cause the danger. Generally it is ill-defined procedures, or unclear instruction.

Have you experienced any of these difficulties while carrying out tasks as a diver?

I believe that the safety of divers starts from the engineering design and the procedural control of those working onshore. Badly written procedures can lead to ambiguity and this can lead to hazardous situations, perhaps with a diver opening the wrong valve and releasing built up pressure.

Kyle McFarlane's picture

I agree with Connies post about how the dangers assosciated with diving increase as the depths increase, however I feel that due to this the advantages that divers have over ROVs are only really applicable in certain situations. As I am not a diver myself and have no diving experience I could not even estimate at which depth this would be the case however I feel it shouldnt be too difficult to find out. 

 After this depth (what ever it may be) I would imagine that the diving operation becomes too high risk and the use of purpose built ROVs would be more applicable.  As mentioned by Karin there is a whole team of people responsible for the diver and therefore these operations are incredibly expensive which is a further reason to increase the use of ROVS when the depth is significant. 


To conclude I feel that divers have a multitude of advantages over ROVs, as mentioned by Connie, however they also have disadvantges, the long list of health and safety concerns mentioned throughout this discussion, It is my opinion that the advantages that divers possess over ROVs is only relevant up to a certain depth. 


Also I fully back Savitas comment, I dont think the rules in place are 100% infalible if they were they would be one of the few, if not the only, completely safe systems in the world.   

Hani Shobaki's picture

Richard, there are many difficulties involved in every dive, and it is commonly said that compared to the surface the same job takes 7 times as long underwater. As Karen mentioned poor visibility is one of the main issues encountered while working underwater. It requires great visual special awareness as procedures are often carried out ‘blind'. It also poses risk when there are objects being lowered and lifted from above. If they can't be seen, they can't be avoided. As well as bad visibility, procedures carried out mid water have of additional problem of the diver floating. With no ground to support you, it is difficult to move things as there is nothing to push against. In past people would attach themselves to the pipe or pile they were working on, this is very dangerous though as a fixed diver is unable to quickly move out the way of an object coming towards them.

Connie Shellcock's picture

According to a paper on the Neurological effects of deep diving,
Gronning et al quote”There will, however, always be a need for human divers in
the technically more advanced underwater operations and for contingency repair
operations.” This emphasises my last point of how we need to advance technology
to allow divers to safely reach further milestones. This paper concludes that neurological
effects have been seen in divers in the decompression stage, but at the same
time still emphasises the value of divers in the North Sea. I do agree that an
ROV should be used over a diver if it can be as there is no point risking human
life if you don’t need to however I still feel there are limits to what an ROV can
do in this day and age.
Aarli 2011)

GRØNNING, M. and AARLI, J.A., 2011. Neurological effects of deep diving. Journal
of the neurological sciences,
304(1–2), pp. 17-21.

Looking through various articles, I'm of the opinion that offshore diving is a dangerous activity. Therefore, in order to ensure safety with these operations, the organisation, the diving contractors, the diving supervisor and the divers themselves have to work together following offshore diving operations health and safety regulations.
These regulations usually assign certain responsibilities and codes to be followed by every stakeholder involved with a dive.
The operating company is entrusted to appoint a vastly experienced diving contractor whom is certified competent to be able to carry out the operation. The company also has the responsibility of assessing any and all hazards that may be involved with the operation and passing on that information to the diving contractor.
The diving contractor's duty regarding health and safety is to assess all risks and prepare risks mitigating plans to manage these risks to an acceptable degree and relay these plans to the dive supervisors and divers. Furthermore, the contractor must ensure that competent divers are allocated to the operation and that they have all the necessary tools and equipment they will need.
The supervisor appointed to the dive must be or must have been a diver themselves. Their role with regards to safety is to ensure that professional and competent divers have been appointed and also to ensure the risk assessment carried out for the operation remains valid as of the day of the dive. They should also inspect equipment immediately before the dive and ensure the divers have all the necessary equipment.
Lastly and equally as important, the divers must have approved certifications for the job in hand. For example, divers with recreational diving certificates should be tasked with offshore operations. They must have certifications for offshore operations. They should also have up to date health and safety records of at least two years, have certificates proving medical fitness to dive.
Offshore diving operations are by no means similar to recreational diving operations as there are many more risks involved.
Kuma Mede

Olamide s Ajala's picture


Ensuing from the discussion by Hani, on the stringent level of training undergone by divers and the risk involved in diving due to poor visibility and other factors, it is important to note that any industrial accident, major or minor, can be seen as having a human error component. Historically, the major cause of industrial accidents emphasised a mechanistic view of human error. However, the ‘man-made disasters’ of the 80s and 90s (i.e. Piper Alpha, Ladbroke Grove, Chernobyl, Aberfan) raised broader issues of organisational acceptance of dangerous or risky practices (Lord Cullen 1990 and 2001). The one vital fact that I think is missing here despite the level of training undergone by Divers is imbibing adequate safety cultureDivers are often described as being individualistic risk takers, adventurous, assertive, and self-assured. Being usually on short-term contract work patterns, they are less likely to perceive safety culture as important for accident control because they receive less consistent inductions on safety culture. References

Olamide Sherifah Ajala Student ID:51230562 Course:Sub sea Engineering

Olamide s Ajala's picture


Ensuing from the discussion by Hani, on the stringent level of training undergone by divers and the risk involved in diving due to poor visibility and other factors, it is important to note that any industrial accident, major or minor, can be seen as having a human error component.

Historically, the major cause of industrial accidents emphasised a mechanistic view of human error. However, the ‘man-made disasters’ of the 80s and 90s (i.e. Piper Alpha, Ladbroke Grove, Chernobyl, Aberfan) raised broader issues of organisational acceptance of dangerous or risky practices (Lord Cullen 1990 and 2001).

The one vital fact that I think is missing here despite the level of training undergone by Divers is imbibing adequate safety culture

Divers are often described as being individualistic risk takers, adventurous, assertive, and self-assured. Being usually on short-term contract work patterns, they are less likely to perceive safety culture as important for accident control because they receive less consistent inductions on safety culture.


Olamide Sherifah Ajala Student ID:51230562 Course:Sub sea Engineering

Alan J Glennie's picture

Diving IS a risky activity, but I would argue that it is less risky than driving a car on a motorway as although commercial diving has the potential for  high consequences, it has a low probability due to the control measures in place. You hear of someone getting killed in a road cash daily. The HSE acknowledges that diving is risky and under its Offshore division sits its Diving Group. Within the group specialist inspectors deal on a daily basis with the industry through (Ref 1): ·         Inspections·         Accident and incident investigations·         Enforcement of statutory requirements·         Attending industry events·         Providing guidance and advice·         Indentifying, developing and promoting best practices Commercial diving in all UK designated areas of the UKCS comes under the HASAWA (1974) and the Diving at Work Regulations (1997). These regulations lay out the duties of Diving Contractor in order to ensure the dives are ‘planned, managed, and conducted in a manner to protect the Health and Safety of all persons taking part in the project (ref 2). The key items being: ·         Creating a Diving Project Plan·         Duties of Supervisor·         Duties and restrictions of divers·         Duties and restrictions of persons engaged in diving project For advice on meeting the requirements of the regulations (Commercial diving) the HSE have published an ACOP – Commercial Diving Projects Offshore: Diving At Work Regulations (1997) – L103. This covers work within the UK sectors of the UKCS but not working in other sectors. As mentioned in other posts it is the IMCA International Code of Practice For Offshore Diving (IMCA D 014) Ref 3 that diving contractors will follow but it must be noted that certain national regulations may be more stringent and must take precedence. Ref 1: 2: 3:  

As we all know diving is a high risk work. There a many risk associated with diving. One of the risk associated with diving is the noise explosure. They are exposed to high level of noise during there routine work. Underwater hearing is different from hearing in air. Sound in water can propagate freely through human body. Many studies associated with this came to a bad news, that of hearing loss in divers. These defects are due to the combined effect of noise, pressure, decompression illness. The source of noise during diving are underwater noise, dive site noise, self generated breathing and helmet noise, noise of the tool and compression chamber. So the noise dose received by the diver is very high. So noise control device should be used. 





Alan J Glennie's picture

In response to your post, I agree that noise travels further under water, this is why whales can communicate over great distances. However, the only common planned operations that would normally affect a diver working would be that of using a piling hammer or carrying out a seismic survey close to the vicinity of a diving project. There is specific publications from the Diving Medical Advisory Committee (DMAC 06 – The effect of sonar transmissions on commercial diving activities, and DMAC 12 – Safe diving distances from seismic surveying operations) Ref 1 which provide  guidance on determining the safe distances that would apply to these activities. These distances would then be written into the dive project procedures and form part of the task risk assessment. During any dive, if the diver reports that he is experiencing any discomfort to his ears, even if it is outwith the calculated distance, the diver would return to the bell and be recovered until the activity was stopped. As you can see, there is existing mitigations that are driven by industry guidance in order to make sure the divers are not subject to any hazards which could affect their hearing. I am not aware of any long term effects to hearing caused by saturation diving as divers are subject to regular medical assessments of which includes hearing tests. 

Ref 1:


Mostafa Tantawi's picture

Based on my previous experience as a ROV operator, while Hani made it clear that training can offset the risks of diving, there is still a human life in the water which without proper communication and supervision can be greatly in danger, It happened that a mistake from a crane operator almost caused a diver his life (diver was hit by an anode skid because the crane operator didn't wait for the diving supervisor command). My point is that when a diver is in water alot of factors (human and other) can affect his life. As an example the DSV should turn off all its engines before the diver gets into the water, which means that DSV must have a 3 or 4 mooring anchors rather than Dynamic positioning. An adequate work permit must be signed by the captain to ensure all the safety measures are in place. The diving operations are very sensitive to weather conditions. Above all this there is always a human risk in stake which isn't always an appealing thing for an operator, therefore now days Operator companies tend to use ROV even in shallow waters (less than 150 m)

Mostafa Tantawi
Masters Of Subsea Engineering, University of Aberdeen

Alan J Glennie's picture

The main hazards surrounding commercial diving relate to the environment that the diver is working in i.e. the sea. Firstly, there is no air to breath. Secondly, it is extremely cold (typically around 4 degrees C). Finally, the diver is working and living in an environment where he is subject to increased physical pressure (where a sudden change could be fatal). These are in addition to the hazards involved in executing the work.

To mitigate the lack of air while working in the sea out of the diving bell, the diver is supplied with a mix of gases to allow him to breath. These composition of these are constantly monitored and vary depending on the diving depth. These gases are prepared on the diving support vessel (DSV) and flow through a pipe (part of the umbilical) and down to the divers helmet.  Should a problem occur in that line there is a second line within the umbilical which supplies gas to the diver (the pneumo line) that is used to give a depth measurement to the dive supervisor. The diver also dives with ‘bail-out’ bottles on their back which allow for up to 45 minutes of gas should the umbilical be severed. It is also ‘normal’ in the UKCS for two divers to be out diving at the same time with one ‘tendering’ the other. Each diver can provide gas for each other and assist the other getting back to the diving bell should a problem arise. It can be seen that there are many back-ups or safe guards in place for the supply of breathing gas. Dedicated personnel are responsible for ensuring the supply of gas and are called Life Support Tenders / Supervisors.

To mitigate against the cold the diver wears a wet suit that contains pipes down the torso, arms and legs. These pipes contain small holes to allow the supply of warm water from the dive support vessel in order to keep the diver from getting pneumonia. The diver is in constant communications with the dive supervisor who instantly controls the temperature of the water. In the event of water supply failure the diver would make his way back to the dive bell until the issue is resolved.

To mitigate against changes to the physical pressure the diver is maintained at the pressure at the subsea worksite (for every 10m below the surface this would be approximately 10 bar increase). When the diver goes into saturation the system is at normal ambient pressure. Once sealed, the chamber is brought up to pressure at a steady speed. This pressure is maintained for the duration of the work at the site then varies to suit the other working depths. Once the diver is ready to end his time in sat, he is decompressed back to normal ambient pressure. This takes much longer and is called the decompression time. If the pressure is  reduced too quickly the diver could get air bubbles in his blood (the bends) and if a sudden pressure drop occurs internal organ failure can result. It is therefore very important that the saturation system is regularly maintained and certified with strict adherence to operating procedures as a simple task such as getting a meal into the diving chamber can be fatal.

As can be seen, the diver is at the mercy of many very responsible people on the DSV and the diver’s life is in their hands. It is of the utmost importance that the guidance contained in the ACOPs is rigorously adhered to especially relating to Equipment (certification, testing, inspection & maintenance) and Personnel (training, competence & qualification). This will ensure that the high consequence hazards have a very low probability of occurring and maintain the safety of the divers.

Hani Shobaki's picture




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Alias, I agree
with you on the noise issue. For anyone who has ever been underwater in a
swimming pool, they may have noticed that certain high-pitched sounds, such as
someone cracking there joints, or knuckles, can be heard from a long distance
away. While other noises don't travel well at all. I'm sure the long-term
effects could be really bad on ones ears.


As offshore
divers tend to wear brass helmets their heads tend to remain dry, this air
barrier between the water and ears may offer some sort of sound attenuation. In
addition to this ear plugs or defenders could be used, however care would have
to be taken with the increase of pressure. If the air space inside the ear was
sealed from outside by the earplug, the building pressure could force the plug
inside. Therefore the earplug should be vented to allow air equalisation, it
would be very expensive to abort a dive because the diver was having ear
equalisation issues.


Another way of
mitigating this risk would be to have better communication topside. If
potentially damaging sources of noise could be temporarily shut down, at least
some of the 'avoidable' noise could be reduced.


A good example
of this would be a ship's sonar that could produce a potentially damaging
sound. It would be wise that a shut off list of these types of devices is
produced before anyone enters the water. If they can't be switched off, a risk assessment
would be necessary to log their potential effects.


While on the
topic of shutting off equipment. Has anyone considered the effects of using
divers and ROV's around dynamically positioned vessels?

Alan J Glennie's picture


As mentioned in my previous post the only issues (I know of) that affect the divers are activities such as using a piling hammer or seismic guns in close proximity to the diving project. The divers are not affected by the ships sonar or the vibration from an ROV next to him or the vessel thruster. A very common task for a diver is to break existing flanges by removing large bolts. These are slackened using a flogging spanner which is a short spanner with a thickened end designed for being repeatedly hit with a hammer to loosen the nut. This has no effect on the divers ears / hearing other than he hears a slight tap.

The diver is in constant open communications with the dive supervisor and can be heard throughout the dive vessel on the dive screens (all focus is on the diver as the whole vessel is there to allow him to work on the sea bed so the screen can be found all over). You can therefore hear whatever the diver hears and what he says. This is mostly the constant noise of the breathing and their speech (both the diver and the supervisor) along with the little taps from hammering the flogging spanner.



Hani an experienced diver has given very useful insight on the extent of risks faced by divers in offshore operations. This notwithstanding, research has shown that although diving operations to day can be considered safer than 30 years ago, diving is considered one of the most hazardous offshore activity. Statistics shows over 50 divers have died during diving operation in the North Sea alone within the past 45 years. A fatal accident rating of 20 deaths per 100,000 divers in the UK is considerable high when compared to the overall workers fatality rate of 0.8 deaths per 100,000 accidents (Sherman, 2009). UK diver accident records between 1996 and 2008 have being tabulated and reflected in Table 1 below. The amount of dangerous occurrences which could have resulted in fatalities can be seen to be quite high for this segment of offshore operation with few employees.   

Table 1 RIDDOR reported incidents for Offshore Diving 1996-2008 (Sherman 2009)


Chris, the chief inspector of Diving UK HSE, has in his research which correlates world diver accident reports, established that most diver accidents have being a resultant of non-adherence to codes of practice, regulations and industry guidance. This is adde to other factors which includes poor visibility due poor light characteric underwater and the risk of collision.

 With most experienced divers getting towards retirement, it is imperative for new generation divers to learn from past industry mistakes and develop safe work attitudes as contained in the various industry standards regulating diving (Sherman2009).  



Chris Sherman 2009. “Offshore Diving Safety- Challenges and Concerns”.

 Offshore Technology Conference Houston, Texas, - 2009.


Dr. Tan,

I have sent a correct image to your email

Henry Tan's picture


Omololu Oyebola's picture

Thought diving operation is a highly paid one, something I will love to do :D, it comes with its own risk. Deep diving is defined as diving to depths more than 50 m of seawater and is mainly used for offshore intervention purpose (Grønning, Aarli 2011).  

On a commercial scale, diving is widely recognized as a hazardous work activity and statistics shows that in the last 45 years, over 50 divers while working offshore oil and gas industry in the North Sea (Sherman 2009) and according to HSE, the first diving fatality in the UK sector was in the early 1970s. Before the advent of remotely operated vehicles, diving incidents was on the rise. In 2010, two personal injuries were reported during saturation diving. 


UK Diving incidence 1996-2008


The table above shows statistics of diving incidents for 1996 – 2008. (Source; RIDDOR)

The lessen diving offshore incidence, the following should be taking seriously;

Competence of personnel should be maintained, regular offshore trainings.

New divers should go through initial training regimes and be made to serve probation for a period of time before venturing into frequent diving operations. Akin to the aviation sector, where pilots are made to have a minimum amount of practice flying time under their belt, before flying a commercial plane, divers should do pseudo diving before the real field experience.

Constant review of training and competence assessment should also be reviewed regularly.

Ensure drilling operations are not ongoing while diving to reduce the risk of snagging umbilical supply line to the diver as this caused a major fatality a while back

Nobody gets hurt should be the motto for any diving contractor, so as to reduce the incident rate to as low as is reasonably practicable.



GRØNNING, M. and AARLI, J.A., 2011. Neurological effects of deep diving. Journal of the neurological sciences, 304(1-2), pp. 17.

SHERMAN, C., 2009. Offshore Diving Safety - Challenges and Concerns, Offshore Europe, 8-11 September 2009 2009, British Crown Copyright. 



Hani Shobaki's picture

Alan I agree with your two last posts, however your second last post there is a minor nit pick with your pressure per m ratings. You mentioned 10 bar per 10m, it is actually approximately 1 bar per 10m, plus 1 for ambient. E.g. 90m = 10 atm.

Saturation diving as you say is risky, but is actually safer for the diver than coming to ambient surface pressure of 1 atm after each dive. This is because if he is maintained at bottom pressure for the extent of his work, the diver will only need to decompress once, rather than 14 times on a two week rotation. Assuming the bell and decompression chamber are in good working order, this is a much safer option.

The only thing to consider is the long term effects of saturation diving. Todnem et. Al. (1) mentions that permanent neurological damage has occurred in divers who have spent many years diving at high depths of 150-500msw. This issue is often overlooked because of the relatively low ratio of saturation divers compared to SCUBA divers who are more susceptible to short term problems like nitrogen narcosis, decompression sickness, and arterial gas embolisms.

Along with this these symptoms occur over a long time, and saturation diving is a relatively new phenomenon. If diving is to have any place in the this industry, chronic effects like this need to be addressed.

1.Todnem, K., Nyland, H., Skeidsvoll, H., Svihus, R., Rinck, P., Kambestad, B., Riise, T., and Aarli, J. A. Neurological long term consequences of deep diving. Journal of Industrial Medicine. Vol.48(4). 1991

Alan J Glennie's picture


You are correct with the pressures, a typing mistake on my behalf. However, saturation diving is not new and has been around a long time. First done in 1938, a large majority of the infrastructure in the UKCS has been installed and maintained by saturation divers since the 1970’s.

Regarding the long term effects, I know that bone necrosis is an issue.

Ref 1:

Ref 2: 


Alan J Glennie's picture

In the early 1990’s a group of divers in Norway set up the North Sea Divers Alliance (NSDA) in order to draw attention to the number of divers that were killed in the North Sea. During the period 1965 to 1990 there were 56 confirmed diving fatalities in the North sea 17 of which were in the Norwegian sector(Ref 1). However, since 1987 there have been no diving fatalities in Norwegian waters (Ref 2). This is partly down to a reduction in diving activities there (from a peak of 100,000 work hours in 06/07 to around half that at present) but also from changes to the regulations driven by a drive to improve the safety culture surrounding diving safety.

During the oil boom up to 1990 there appeared to be a focus on profit rather than safety. This is said to have resulted in several the death of many divers (Ref 3) whose families have battled with the Norwegian government in a class-action law suit.  This has brought financial compensation although the government have failed to admit responsibility.

In the late 1980s a new risk-based framework was implemented in order to reduce diving risk. As a result new HSE legislation was introduced: NORSOK U-100N (Ref 5) which relates to Manned Underwater Operations (including diving). This has been driven by the Norwegian Petroleum Directorate (NPD) which, in 2004, became the Petroleum Safety Authority (PSA). Other related documents include: NORSOK U101 – Diving Respiratory Systems and NORSOK J103 – Marine Operation.

To assist in the understanding the differences in the UK and Norwegian legislation IMCA have issued guidance document IMCA D 034 – Norway / UK Regulatory Guidance for Offshore Diving (NURGOD) (Ref 6).

Today, Norway has a very good safety record with respect to diving. Last year 8 minor injuries were recorded and there have been very few since 1987 (Ref 4). This has been the result of a focus to improve the legislation and safety culture within the diving or MUO industry.

Ref 1: 

Ref 2:

Ref 3:

Ref 4:

Ref 5:

Ref 6: 

Marinos Ioannou's picture


I believe that
this kind of job can turn really dangerous while the divers work in high
pressures, really low temperatures and low lighting. Even when a worker
on-shore is welding some metallic parts of a constructing platform, he can be
exposed to serious hazard. So just imagine what can happen when he will be a
lot of meters under the water. At any time, he can be exposed in a situation
that a big metallic piece will hit and trap him underwater, or he can be
exposed without oxygen, or in a really freezing environment with really high
pressure applying on his body. 


Marinos Ioannou

Marinos Ioannou's picture

I would like to add something more on what I previously said. As I know from personal experience in diving, to be a good and healthy diver you need to follow some basic rules. Basically, those rules involve the pressure that your body is exposed in order to help the divers to gradually go deeper and deeper in the sea. Anyway, most of the divers who like to challenge their selves or even other divers, some times can over react and may expose their selves in an unwanted situation. When that happens, the worst scenario is chronic deseases that lead to death.

Marinos Ioannou

Hani Shobaki's picture

Following Alan's post about legislation, I thought as nobody else has, I would mention the Approved Codes of Practice and Guidance by the HSE. Diving operations are divided into five sections: commercial diving projects offshore (L103), Commercial diving projects inland/inshore (L104), Recreational diving projects (L105), Media diving projects (L106), Scientific and Archaeological diving projects (L107).
For each activity, there are different risks involved and different levels of supervision, tendering required. For example, a marine biologist may carry out scientific diving. It may be as simple as collecting a sample of marine plant life, and it is relatively safe. There are few hazards and very little topside communication is necessary. On the other hand offshore diving projects, carry more severe hazards combined with more complex tasks. Therefore as Karin mentioned some diving operations may have large numbers of topside staff supporting one diver.
The HSE has designed the codes in order to reduce the dangers and hazard involved in diving. They also have the power to halt diving operations indefinitely if these are not adhered to.

Health and Safety Executive. Diving at Work Regulations. 1997. (accessed 01 Dec 2012)

Alan J Glennie's picture

The International Marine Contractors Association (IMCA) is a trade association made up of over 800 organisations from over 60 countries with a respected voice for promoting good health and safety practice in a number of marine areas. One area is diving. The member organisation comprise all the key diving organisations and provide a body in which industry experts from these organisations can work together to develop the industry with respect to: publishing good practice guidelines, monitor and lobby regulations and promote the industry to name a few.

One of the areas where IMCA is noticed is in its sharing of incident-related information sharing through its Safety Flashes (ref 1). When an incident occurs, member organisations will inform IMCA of the details surrounding an incident or potential hazard and a Safety Flash will be produced and issued to member organisations and on the public website. The reporting of these near misses and incidents (including any potentials) help raise awareness and is a key factor in helping to further reduce the number of incidents thus making the industry safer.

IMCA also send out safety flashes forum other related organisations e.g. Step Change in Safety, HSE , etc

Ref 1: 

Etienne Gunter's picture

I would just like to mention one thing regarding the long term health risks of saturation diving. Even though lots of tests can be done today, I believe that there is still a lot of speculation of the long term effects. To illustrate my point:

The 1st commercial saturation dives were carried out in 1965 by Westinghouse to replace faulty trash racks at 200 feet on the Smith Mountain Dam  [1]. So if you were 20 years old at that stage, you would be 67 today. Taking into account that at 1965 there were not that many saturation dives being carried out (and divers) compared to today, there will not be that many people around today that can be monitored to determine the long term effects.

We might be better off than we think?


Alan J Glennie's picture

Earlier posts have identified a number of accidents and incidents to the divers have been attributed to the actions of the Diver Supervisor i.e. bad supervision. It must be noted that, in order to fulfil a role within the diving industry e.g. diver, dive supervisor, life support tender, etc, there is a requirement to demonstrate the correct competencies and qualifications have been attained. Only then will the diving contractor issue you with a ‘Letter of Authority’ that allows you to execute that role offshore. In order to become a saturation (gas) diver, a diver must first obtain the relevant IMCA approved air diving qualification then amass enough experience in order to be classed as competent to be an air diver. Only when they have achieved this can they progress to become a saturation diver. This involves the same process of attaining the IMCA approved qualification then obtaining the relevant experience to be classified as competent (Ref 2).

The dive supervisor has overall responsibility for the overall diving operation and there are strict rules to ensure they are competent (Ref 3). IMCA C 003 – Guidance on Competence Assurance and Assessment in Diving Division lists the qualifications and experience required in order to demonstrate competency in this position e.g. must be a trained saturation diver with over 400 hours experience, must have completed at least 350 hours on the dive panel under supervision, have over 350 hours experience as a life support technician, and so on.

To summaries, it can be seen that in order to become a dive supervisor, an individual must have extensive experience as an air diver, sat diver, life support technician and have panel experience in order to demonstrate competency in the task. This is a very rigorous process taking many years and questions why several incidents are being caused by ‘bad supervision’.

The same level of competence applies to all key personnel for diving operations e.g. vessel marine personnel and diving personnel (Ref 3 and 4) and demonstrates a very high standard of personnel involved in commercial diving.

Ref 1:

Ref 2:

Ref 3:

Ref 4:  

Richard Milne's picture


To add to your point about competence within diving operations, this should also extend to any engineers who are offshore on a Dive Support Vessel. The engineers should all be fully aware of the work scope, and any other dangers which may surround the diver at all times. The engineer should be able to explain the next step quickly and concisely, along with the dive supervisor. The dive supervisor is ultimately responsible for the divers life, but an engineer observing the diver should never be too far away from the operations centre.

To go back to one of my previous points, there have been problems in the past with mis-identification of valves which the diver is due to operate. Some of the risk of this occuring could be mitigated if divers were fitted with a GPS tracking device, so that the personnel on the DSV can see the divers position AT ALL TIMES relative to the vessel and any other transponders which may have been poitioned previously. This would mean a second level of confirmations that the diver is in the correct place and could save a diver from opening a valve which is holding pressure.

Alan J Glennie's picture


 The mis-identification of valves should be covered in the task risk assessment that is required under clause 6 ofthe diving regulations. Although there is much details on the the competency requirements for marine and diving personnel. I cannot find a reference to the required competencies for engineers (although i have to add it would be preferencial to have experienced engineers involved).


Thomas Ighodalo's picture

i would like to hightlight further on the health risk faced by diver due to the pressure change exposure.

Pressure Exposure: with increasing depths the pressure faced by the diver increases and the resultant health risk are high pressure neurological syndrome, compression arthralgia, decompression illness, barotrauma and dysbaric

Solutions to this involves:

1. Safe diving practices

2. Equipment in use: using the right gear for the right depths can never be overemphasized. 

3.  The risks of trauma as well as  the control of toxic exposures should be looked into, also care must be paid to the individual diver as individual susceptibility can not be overuled.



1. The diving Medical Advisory Committee- statement on commercial diving and health 2006



"Everything we hear is an opinion not a fact"

Mohamed H. Metwally's picture


Diving is the most dangerous activity ever in offshore industry!

Irrespective of
the dangers of marine organisms, sharks, etc...The hydrostatic pressure
underwater could end diver's life if he does not follow diving safety

That is why IMCA
(International Marine Contractors Association) has set its standards of
how to dive and who should dive.


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