The Magazine for Underwater Professionals

May/Jun 2016


Development of a global hyperbaric rescue service - part 3

In the third of a series of articles on hyperbaric rescue, Brian Redden, director of global hyperbaric rescue services at UK-based JFD, looks at the hyperbaric lifeboat

A typical 12-man self-propelled hyperbaric lifeboat interior

In Parts 1 and 2, published in the January/February 2016 and March/April 2016 issues of UCi, I reviewed the general history of the modern commercial diving industry and the start of saturation diving operations, some 40 years ago. Here, in Part 3, I will look at development of the hyperbaric lifeboat to date and ask whether today’s systems are fit for purpose or do we still have some way to go before we can say state-of-the-art is being employed to ensure the divers safety.

The 2011 BP document Diving Policy Statement 002 stated that on all BP managed and operated worksites diving contractors must have in place “a proven method of ensuring the diver’s survival in the event of an incident that compromises the mother vessel or installation” and stipulated that hyperbaric lifeboats had to be of the controlled launch, self-propelled type, that self-propelled hyperbaric lifeboat (SPHL) transit times after launch had to be as short as possible and that a dedicated hyperbaric reception facility (HRF) with medical support had to be available to receive the SPHL.

While it is the case that since 2011 the major clients for saturation diving, the oil companies, have been advocates of improving diver safety through the activities of their International Association of Oil & Gas Producers (IOGP) Diving Operations sub-Committee (DOsC) with their September 2014 Report 478 laying out the performance requirements for emergency hyperbaric evacuation, it is also the case that only a relatively small number of the world’s oil companies are IOGP members and that implementation of rescue services differs significantly around the world.


SPHLs are mandatory in the saturation diving areas of the world categorised by having stable political regimes, where IOGP members are the main oil producers and so have usually also introduced adherence to International Marine Contractors Association (IMCA) guidelines. In the North Sea for example, SPHLs have been in use for some 20 years. However, in the Middle East, Gulf of Mexico and South East Asia regions HRCs (hyperbaric rescue chambers) are still widely used, unless a North Sea type DSV has been shipped in for a specific duration diving campaign, in which case it will have one or two SPHLs and its LSP (life support package) and HRF support infrastructure will usually have been shipped in (and out) with it.


The HRC is simply a pressure vessel with enough seats or bunks to take all divers in saturation, housed in a protection frame, with enough buoyancy so that it floats. They have no built-in life support other than CO2 scrubbers and depend upon being picked up quickly after launch and taken into a port where their LSP is connected and the divers decompressed in situ. Sometimes a HRF is available, but this is the exception rather than the rule. It is generally thought that over time, HRCs will be phased out and replaced by SPHLs, but in relatively shallow-water areas not too far from land. In reasonably busy shipping areas there is little real incentive to do this. It is more likely that the diving contractors in these areas will consider the lesser investment of upgrading their HRCs with environmental control systems to heat or cool the chamber.

So what questions are being asked about SPHLs? The first is: why has the design of SPHLs not really changed much over the past 20 years? The short answer is that one manufacturer has done a great job in developing a supply monopoly, delivering the majority of the SPHLs built since about 2003 to diving contractor clients around the world. It had acquired the original design rights and moulds, etc. of Mulder & Rijke, a Netherlands-based company which was one of the first manufacturers of SPHLs. While the manufacturer initially improved on the original design, once it had established itself as the “go to” company for SPHLs, there have been no real incentives other than to make incremental changes to the lifeboat design over the years. Where it has progressed is in the areas of classification/approvals and capacities. Its DNV (Det Norske Veritas) prototype approved SPHL design has gained approval from ABS (American Bureau of Shipping) and service approvals from GL (Germanischer Lloyd) and LR (Lloyds Register) and is now available in three sizes, from a 9.5-metre 12-diver version to a 13-metre 24-diver unit.

  • Typical SPHL. Image courtesy of JFD Ltd
  • Typical JFD Divex modular saturation dive system with HRC. Image courtesy of JFD Ltd

As previously said, the SPHL differs from a HRC in that it is self-propelled and has the environmental control systems on board to heat or cool the chamber and keep the internal atmosphere CO2 and humidity within acceptable levels for the comfort and life support of its diver occupants. While it is true that the SPHL is self-propelled, and this is clearly an advantage over a HRC, most SPHLs have a maximum speed of six knots and it is now generally accepted that in any inclement weather conditions the likelihood is that it would be unlikely to reach its diving contractors hyperbaric evacuation plan (HEP) nominated port of safe haven and the HRF there, “under its own steam”, within the 54 hours life support limit set by the IMCA guidelines.

A group of UKCS diving contractors have recently carried out some SPHL towing trials to try and determine what speed and under what weather conditions a tow can be undertaken, but at the time of writing no further information is available. However, in towing trials some years ago it was found that the SPHL hull shape restricted safe maximum towing speed in fairly benign weather conditions to some four to six knots maximum. So the towing option, although better than nothing, is not the ideal SPHL recovery method.


It is worth explaining here the 54 hours life support limit figure mentioned earlier. The IMCA D052 Guidance on Hyperbaric Evacuations Systems states that SPHL total life support duration must be a minimum of 72 hours. To give a safety margin, the Guidance (Section 2.4.2) quotes 75% of this, i.e. 54 hours.


Therefore, once launched, the divers in saturation have only a nominal 54 hours of life support capability in the SPHL before they should be either hooked up to a LSP or docked onto a HRF. This is a critical period, when the divers are at most risk. One innovation which would improve the divers lot at this time is the CSMTS (Critical System Monitoring and Tracking System) developed by Aberdeen, UK-based company Fathom Systems. This is the only real innovation in SPHL outfit to be put onto the market in recent years, but it has not been widely adopted.


The CSMTS is a stand-alone data acquisition, recording, communications and transmission system to monitor life-support, machinery, environmental and positional data from the SPHL during an evacuation. This data is gathered by a collection of sensors which are installed alongside primary instrumentation, and whose data is logged locally and transmitted via the Iridium satellite network to emergency response personnel onshore.


The Iridium satellite communications system provides automated data transmission of the measured parameters and also provides voice communications via a handset for the SPHL crew to allow bi-directional calls to any telephone number globally, initiated by either party. The existing voice link to the SPHL chamber communications system also permits rescue personnel to talk to divers inside the chamber via the satellite telephone link and through the onboard helium speech unscrambler. The CSMTS is compatible with all existing manufacturers’ voice communications systems installed on SPHLs.


CSMTS can transmit biomedical instrumentation worn by the divers to measure heart rate, temperature, respiration rate and monitoring of specific medical instruments in the chamber (blood pressure monitor, O2 saturation, etc.). It can also make global emergency broadcast/identification, permitting emergency services to monitor the status of any incident via the internet and to provide advisory information such as interface trunk size and position, emergency life support package connection details, numbers and details of occupants and details of DSV operator and emergency response numbers. It could also enable automatic hand-over from vessel-based diver monitoring systems (DMS) to the SPHL-based CSMTS system including divers’ individual historical exposure profiles for current saturation period. This could facilitate remote monitoring of therapeutic treatment of specific divers and management of decompression profiles either in the SPHL or at the onshore HRF.

If required, Fathom could also automatically monitor the status of all equipped SPHLs continuously. In the event of a launch, an immediate alert would be received allowing the shore-based response teams to be notified by telephone, SMS or email. Automated periodic ‘health check’ interrogation ensures a fail-safe and direct system availability.

At time of writing, I can report that while Fathom designed and built its CSMTS product specifically in response to the OGP (IOGP) Report 478 – which in Section 7.4 stipulates that “critical system monitoring and tracking equipment should be provided”, and goes on to describe its functions in detail – the company has not yet sold one unit!

  • The Fathom Systems CSMTS component parts. Graphic courtesy of Fathom Systems

So returning to my initial question, are today’s SPHLs fit for purpose or do we still have some way to go before we can say state-of-the-art is being employed? My conclusion is that today’s SPHLs are fit for purpose, but there are a number of areas in which they could (and should) be substantially improved. The first is obvious. The OGP Report 478 requirement for a critical system monitoring and tracking system should be enforced. It should be mandatory for all SPHLs to have a comprehensive system.

And other areas for SPHL improvements? Why is the hull design still ‘towing unfriendly’ and, as we move nearer to ‘SPHL recovery’ being mandated (rather than launching and leaving it to get to its port of safe haven under own power), how about a good look at how we launch and recover the lifeboat? But more of this in next issue.

The BGR story - tales from nearly 50 years in the diving industry
  • Brian Redden

This tale clearly demonstrates how diving operations management has improved over the years. In the 1970s we were killing around 12 divers every year! In the 70s diver comms that worked were a luxury rarely encountered. Tenders and deck crew got the briefest of instruction on what was to be done and formal training in things like tending, rigging, underwater cutting and the use of hydraulic torque tools was at best lax. Quite often, the dive supervisor was chosen because he was either the longest serving or couldn’t be dived because he was hopeless underwater!

Anyway, this story serves to show clearly how personnel training, good equipment (working comms), toolbox talks and properly qualified supervisors have together resulted in the job being much safer these days.

It was 12 March 1973. I was on board the DB (derrick barge) Challenger and we were installing production platform jackets in the Ekofisk field which lies in 210-230 feet (64-70 metres) of water at the southern end of Norway’s North Sea sector, about 280 kilometres south-west of Stavanger.


As usual, I was on the afternoon/night shift. The purpose of my dive was to continue in the removal of a two-inch (five-centimetre) diameter grout pipe which ran vertically from topside down the leg to its base. It was part of the grouting system which pumped concrete into the annulus between leg and pile. Once the grouting had been completed these pipes were removed. The pipe was held in place by brackets welded to the leg about two feet (0.6 metres) apart. The pipe length down to about 60 feet (18 metres) depth had already been removed and the downline was tied off to the pipe end there. My target was to burn off eight brackets then cut the grout pipe itself, so that the approximate 20-foot (six-metre) section with its eight brackets could swing free and be lifted back on deck.

So, picture “the support crew” on deck. The supervisor on the comms in the air dive shack, one man tending my umbilical, one tending my burning gear hose/cable and another tending the downline. A fourth chap was on hand to assist with either the burning gear hose/cable or the downline when these needed to be hauled back to the surface. It would be a number of years before hydraulic line haulers replaced manpower!


It was dark when I jumped in and left surface at 18:21, dressed in a Viking drybag and KMB8 (Kirby Morgan Band Mask 8). The diver comms were okay on deck, but got less audible the deeper I went. However, the visibility was fantastic and I slid down the downline to the job site at 60 feet with no issues.

We had agreed if we lost comms that we would use standard “pull signalling” in which one sharp tug on either my umbilical, the downline or the burning gear hose/cable meant “stop”, two tugs were for “pull up” and three tugs for “lower, or give me slack”. I had a coil of spare oxy-arc hose/cable over my right shoulder and half a dozen Broco rods pushed into a quiver hanging on my weightbelt. I always liked oxy-arc cutting, so I was in my element.

The comms worked just well enough for surface to hear me yell “make it hot” or “make it cold” and the job went really well. I got all eight brackets burned off, so gave two tugs on the downline rope just as I cut through the pipe and it swung free of the jacket. What was supposed to happen then was the guys on deck should have hauled on the rope to lift the length of pipe on board. What actually happened was they paid out on the rope. Even worse, for some inexplicable reason, my tender also paid out on my umbilical and I got slack on the burning gear too. Then one of the pipe brackets hooked up on the coil of burning gear hose on my shoulder and we all started heading for the seabed.


My first instinct was to try and kick swim over to the leg to grab onto it. However, I didn’t really get the chance to, because the pipe was too heavy. As I headed downwards I remember trying to clear my ears as my descent speed increased. I still have vivid memories of the next minute or so. When I looked up I could see the barge hull outlined by the blaze of floodlights. Then I was passing the platform horizontals at a fair lick and remember thinking to myself it was like being in one of those old elevators with the folding wire mesh doors and the aged attendant saying “fourth floor, ladies’ coats, going down, third floor, ladies’ underwear, going down, second floor, men’s suits, going down, first floor, men’s casual, going down”. When I landed in a heap on the seabed I remember thinking, “ground floor, cosmetics and haberdashery” and having a silly giggle to myself.

It took me a minute or two to get my thoughts together and figure out what to do. I was deaf and my head was pounding with narcosis, but survival instinct kicked in. On the plus side I had excellent visibility, plenty of air and wasn’t hurt.


I tried to speak to surface but the comms just buzzed. Looking up, I could see my umbilical, the burning hoses and the grout pipe rope all heading upward. I decided the first job was to get free of the grout pipe and rope so I cleared that away from me and crawled clear. Then I got out from under the spare burning hose that was still coiled on my shoulder. I could then see I was clear and nothing was holding me to the bottom.

I gave two hard tugs on my umbilical and rather than pulling me up, I got more slack. I did this a couple of times more and ended up with even more hose. Eventually they must have given me all the umbilical and it stopped coming down. There was now so much umbilical around me on the bottom that I had to grovel about, pulling it all clear of the grout pipe and brackets to ensure that it wouldn’t entangle and drag me back down once I left the bottom. I then started to climb up my umbilical, but soon realised there was so much weight of umbilical that I could not carry it with me.

I had a small suit inflation bottle so made the decision to crack this to help me ascend. I knew that being on the bottom at about 220 feet with a load of umbilical hanging off me, it was going to take all the air in the bottle to get me buoyant, so it was a one shot “shit or bust” option. But as it was my only option I cracked the valve.



I started upward, making sure to have an arm looped round my umbilical down from the barge to grab onto in case I started going down again, I remembered to take short quick breaths then to breathe out all the way up and to vent air from my suit wrist seal as I got toward the surface. I chuckled to myself as I passed men’s casual, men’s suits, ladies’ underwear and ladies’ coats, then there was the barge keel and I popped out of the surface like a balloon right at the bottom of the dive ladder and held on to it until I got my breathing back under control. I climbed the ladder and waved to the guys as I stepped on to the deck. It was 18:46 and I reckon I had left bottom at 18:44. Total bottom time (TBT) 23 minutes.

The deck crew seemed surprised when I questioned why they had paid out so much umbilical and hose and just left go of the grout pipe rope.

When I had got out of the gear and told the supervisor that I had been “on the seabed and my TBT was 23 minutes”, he scratched his head and said something along the lines of: “Go and have a cup of hot sweet tea. If you get any niggles come and find me and we’ll chuck you in the pot.” As it happens, I had no ill effects at all and was in the water again next shift.

Another of my nine lives used up. The next day I dived at 15:05 to 115 feet (35 metres) – another burning job.

Brian G. Redden





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