Connect with us

Exploration

Confronting the Unknowns of Decompression with the First Electronic Rebreather

How did Electrolung inventor Walter Starck and his cronies decompress from dives to 100m/326 ft before the advent of dive computers or even constant PO2 tables? Dr. Starck explains his procedures and rationale. Deep stops anyone?

Published

on

by Walter Starck
Photos courtesy of Walter Starck

The design and manufacture of the first commercially available, electronically regulated closed circuit mixed gas rebreather in 1968 presented a multitude of problems to be solved in the design and manufacture of the device itself.  Successful development and production of the Electrolung presented an additional problem. Decompression tables were limited, and none were available for a constant partial pressure of O2 with a varying percentage of inert gas as occurs in an electronic rebreather. The US Navy tables were the only heliox tables readily available. Those used in the offshore oil industry were all treated as commercial secrets by the offshore diving companies. Decompression computers had not yet been invented. 

To start with, I interpolated from the US Navy helium tables for an equivalent partial pressure depth for the Electrolung.  Although, by today’s standards, this may seem unacceptably risky, it was less so than may appear. If immediate recompression is available at the first symptoms of any decompression sickness, progression to more serious levels is rare. When recompression is delayed for several hours, or more, to get to a chamber there is a high probability of increasing tissue damage requiring extended treatment and lengthy recovery or permanent impairment. 

A young Walter Starck about to dive in the Coral Sea with his Electrolung in 1971.

My research vessel, El Torito, was equipped with a large (42’’ x 12’) double lock recompression chamber which could comfortably accommodate two persons, or even three if needed. The inner lock was kept pressurized to 30 m/100 ft, so getting to 18 m/60 ft of pressure could be accomplished in less than a minute by just getting in, closing the outer door, and opening a valve to let the main inner chamber equalize with the entrance chamber. An oxygen rebreather also provided for 100% O2 decompression without the fire risk of pressurising the chamber with O2. Having a chamber immediately available reduced the risk of experimenting with decompression profiles to an acceptable level. In practice, there was only one incident where the chamber was needed, and that involved pushing the limits with a repetitive dive to 60 m/200 ft with only an hour surface interval.

While getting into the matter of decompression, I came across an interesting study by the Australian physiologist Brian Hill, who found that the pearl diving industry in northern Australia had developed (by trial and error, including numerous fatalities) a mode of decompression that started deeper, ascended slower, and ended deeper but was faster overall.  Based on this, some relevant physics, and Hill’s own extensive lab work, he proposed a theory of what he called thermodynamic decompression. In this regard, he believed that the idea of avoiding bubble formation by keeping within a hypothetical limit of supersaturation is incorrect, as any degree of supersaturation results in a gas phase beginning to form as a thin film at tissue surfaces, which then begin to coalesce into sub-symptomatic bubbles.


  • Rebreather Forum 4

In his view, the conventional tables were generating sub-symptomatic bends by allowing divers to ascend too quickly and then having to spend a lot of (decompression) time to prevent them from growing into symptomatic bends. If the bubble formation is avoided to begin with by allowing the inert gas to escape through the dissolved gas saturation window provided by the ability of tissues to metabolize O2, decompression can be optimized. 

Diver with Electrolung.  Note pink Baralyme absorbent.  The acrylic bubble was being used for a shark cage.

My study of his material left me with the impression that it was well founded, so I began to titrate decompression toward that direction. This led into a series of 92 m/300 ft dives with 15 minutes descent and bottom time, a slow 10 m/30 ft-per-minute or slower ascent time, a couple of stops for about two minutes at around 46 m/150 ft and 22 m/75 ft, finishing with 15 minutes on pure O2 at 10 m/30 ft. On different occasions, but not at the same time, three other individuals accompanied me, all without DCS in some 30 such dives.

The effort, resources, liability risk, and limited economic potential involved in endeavouring to develop a full set of tables of this kind, as well as my own prime interests in marine science and exploration, ruled against further pursuit in this direction. However, a few years later when I arrived in Australia with El Torito, I got in touch with Brian Hills and had the opportunity to spend several days with him in Adelaide.  He went on to a distinguished career in decompression physiology at several institutions in the US and UK. 

See accompanying Story: Electrolung: The First Mixed Gas Rebreather Was Available to Sport Divers in 1968

Dive Deeper:

For more on Hills and his thermodynamic theory, see: Brian Andrew Hills 

Wikipedia: The US Navy’s Thalmann Constant PO2 Algorithm

NEDU: DEVELOPMENT AND VALIDATION OF 1.3 ATA P02-in-He DECOMPRESSION TABLES FOR THE MK16MOD1 UBA

InDepth (Four part series): Decompression, Deep Stops and the Pursuit of Precision in a Complex World by Jarrod Jablonski

UHMS: PROCEEDINGS: DECOMPRESSION AND THE DEEP STOP (2008)

Immersed: The International Technical Diving Magazine (Winter 1998), Starck, Walter 1998. In Water Recompression: Problem or Solution? by Walter Starck. Reprinted courtesy of DIVER mag.

InDepth: A New Look at In-Water Recompression (IWR) 


Walter Starck is one of the pioneers in the scientific investigation of coral reefs. He grew up in the Florida Keys and received a PhD in marine science from the University of Miami in 1964. Since 1978, his home has been in north Queensland, Australia. Throughout his career in marine biology, participating in expeditions around the world,  Dr. Starck has been extensively involved with development of the technology required to facilitate his activities. In several instances patented inventions and commercial products have resulted. In addition to the optical dome port and the Electrolung other noteworthy achievements in this area have been: The Bang stick—a hermetically sealed underwater firearm for hunting and defense, underwater housings for numerous cameras and instruments, underwater lighting systems, a multipurpose commercial waterproof electrical connector,  design of the unique research vessel El Torito, a 9 meter high-speed diving launch, a 24 passenger eco-tourism vessel, and the Oceanic 8000 Longboat.  The longboat was a long narrow high efficiency powerboat inspired by the efficiency of the log canoes of the Solomon Islands.  He has also built and flown an amphibious aircraft of advanced canard wing design using high technology composite materials. Recently (Aug 2017) he was senior author on an extensive update on the Alligator Reef study that brought the total species list for that locality up to 618 species.

Dr. Starck has authored over 100 articles and books, which include numerous technical and peer reviewed scientific studies as well as many articles in leading popular publications. His photography has been widely published in conjunction with his writing, and he has produced nearly 20 films and videos. Throughout his extensive career, he has managed to inspire not only admiration, but also the ire of some detractors who have taken umbrage at his efforts to inject what he believes to be “a rational perspective on human ecology into the eco-mania that has become epidemic in our struggling Western economies.” His criticisms of the “poor science and blatantly false claims widely used to support various environmental agendas” have earned him some criticism.

Exploration

Finding the Wreck of the “Admiral Knight”

Professional archeologist and tech diver Ewan Anderson recounts the tale of finding the early 1900s steamship the Admiral Knight in British Columbia waters in the spring of 2020—a collaboration of the British Columbia Underwater Explorers (BCUE) and the Underwater Archaeological Society of British Columbia (UASBC). It’s a tribute to the power of “Citizen Science,” and the joys of diving with purpose. Here’s how they found it.

Published

on

By

By Ewan Anderson

The Admiral Knight, formerly the SS Portland . Courtesy PSMHS Williamson Collection, Neg. no. 2877

“Well… I might have a target for you,” read the fateful email that led to our search for the wreck of the early 1900s Admiral Knight steamship.

It was 2019, and Craig Lessels of the Canadian Hydrographic Service (CHS) had been reviewing multi-beam sonar bathymetry datasets — basically, maps of the seafloor — when he noticed a cluster of features lying on the otherwise sandy seafloor, east of Galiano Island in the Salish Sea off the west coast of Canada. 

Thinking the Underwater Archaeological Society of British Columbia (UASBC) might be interested, he forwarded what he had found to UASBC Explorations Director Jacques Marc. 

As it turned out, the UASBC had, since 2006, been looking near this location for the Admiral Knight, a steam-powered freighter that sank after an explosion in its engine caused a catastrophic fire on board.

The Search

The UASBC search began, as usual, with some serious background research.  The research turned up a wealth of information about the vessel’s origins and destruction in 1919. Launched by the Westward Navigation Company of Seattle in 1916 as the Kuskokwim River, the 43 m/142 ft long wood hulled, diesel-engine powered vessel was built to provide freight service between Puget Sound and Alaska. It was re-powered with steam engines in 1917 and renamed the SS Portland, and then renamed the Admiral Knight in 1919 after purchase by Alaska Pacific Fisheries, who may have used it to supply their canneries in Alaska.

On July 26, 1919, a fire broke out in the Admiral Knight’s engine room while the freighter was underway from Seattle to Ketchikan. The crew of 21 barely made it off the ship before it was engulfed in flames; the last six men leaped off the foredeck onto a boat dispatched by the local steam ferry just in time to be saved. Three days later, mariners were still being warned of the burning hulk drifting between Vancouver and Vancouver Island, but there was no sign of the ship by July 30.

The Admiral Knight was forgotten until the late 1950s when a group of divers explored a site near Galiano Island where a local fisherman reported to have snagged his gear on a wreck.  In an interview in 2006, one of the divers remembered seeing an intact wooden hull and some machinery matching the Admiral Knight’s description at depths of 55-64 m/180-220 ft; although this firsthand account came with the caveat that they were “narked out of their minds.” This general location became the focus of the UASBC’s field surveys over the next few years, including searches using towed side-scan sonar in 2006 and a multi-beam sonar survey by Parks Canada’s research vessel, the MV David Thompson. Those searches did not locate anything resembling the Admiral Knight wreck, and its location remained a mystery until CHS’s review of data from deeper water in 2019, just beyond the UASBC’s previous search areas.

The CHS target sits in 57 m/187 ft of water, which puts it beyond the range of the UASBC Explorations “regulars” group, some of whom have been exploring and documenting underwater maritime heritage sites in British Columbia and Alaska since the early ‘80s. As a UASBC Explorations regular myself — albeit with only 15 years’ worth of expeditions in my dive log — and member of British Columbia’s close-knit Global Underwater Explorers (GUE) technical diving community, Jacques turned the project over to me and wished me luck. I had been bothering Jacques for several years to give up his wish list of deeper shipwreck targets, and it appeared that this was my chance to prove that GUE tech divers on Vancouver Island could make a significant contribution to the underwater cultural heritage record on B.C.’s coast.  

Multi-beam sonar image of the wreck. Credit: Canadian Hydrographic Service

The Plan

We were ready! In short order, I had a team of qualified and enthusiastic GUE divers, a dive boat, and a dive date in April 2020. And then we were interrupted by the pandemic. Organised diving took a big step back while everyone tried to figure out how to navigate a variety of restrictions and act responsibly in the face of this century’s biggest global health scare. Focus shifted to community-building through impromptu dives, and the big projects, like our plan to identify the Admiral Knight, took a back seat.  

Dive boats available for projects around south Vancouver Island changed, too. GUE instructor evaluator and Vancouver Island resident Guy Shockey bought a boat, the Thermocline, brought it up to the island from Puget Sound, then learned how to drive it (possibly in that order). While the boat was still just a twinkle in Guy’s eye, he told me he hoped to make Thermocline a platform for divers to do world-class diving, but for that to happen it was up to the local GUE community to demonstrate that we had interesting project dives to do. He and I agreed that identifying the Admiral Knight fit the long-term community goals perfectly. Soon after the Thermocline arrived at its permanent home in Vancouver Island’s Maple Bay, Guy started referring to himself as “The Boat Driver,” so I knew he was seriously committed.  

  • Rebreather Forum 4

The Dive

By early 2022, our diving activities on the west coast were back to their pre-pandemic norms, and the way seemed clear to dive the Admiral Knight. So, on a sunny weekend this past August, with water as calm as glass, I found myself dropping through the cool, emerald-green depths towards the bold future of underwater archaeology in my backyard. 

Dropping down the shot line with me was Jason Cook, an instructor and fellow rebreather diver. As we descended, I had a head full of plans and checklists, and handfuls of equipment. Try as we might to keep things simple, we were determined to complete a minimum number of tasks and needed the gear to pull them off.  In addition to our JJ-CCR rebreathers and bailout cylinders to do the dive, we had a full-frame camera and two pairs of large video lights to document the wreck (if it wasn’t just a pile of rocks we were dropping onto). Jason had a 120 m/400 ft reel in case The Boat Driver dropped the shot in the middle of nowhere and our identification dive turned into a search for, well, anything.  I had an additional large surface marker buoy (SMB) stuffed in my left thigh pocket, which we planned to launch without a line attached to signal the next dive team that we’d found something worth diving.  We each had a diver propulsion vehicle (DPV) to drag all this stuff around if the current picked up (strong currents are common in our region, but also highly localised, and nobody was sure when slack tide was at this new site).

The visibility on the descent was just over 20 m/60 ft, which is fantastic no matter where you are in the world. As we passed 40 m/130 a huge grey shape swam right in front of me — a shark! — no, just the biggest lingcod (Ophiodon elongatus) I had ever seen. As the monster fish disappeared, we hit a layer of low-visibility water hovering about 5 m/15 ft off the seafloor. It appeared we were going to be diving in the dark — and the cold, since it was also suddenly only 9° C/~48° F. Finally, the shot appeared below us, lying on a featureless, sandy plain. There wasn’t even a pile of rocks pretending to be a wreck in sight.

Like the optimist he is, Jason quickly got out his reel to tie-off and start a search.  I, on the other hand, stared dejectedly into the gloom, where I could just make out some white blobs in the distance. But wait a second — the blobs must be plumose anemones (Metridium farcimen), and anemones must be attached to something! I got Jason’s attention with a flash of my light, and we headed off towards the anemones.

It turned out that our search for the wreck was brief — the anemones were only about 10 m/30 ft away, attached to a driveshaft just forward of a small steel propeller. It was a convenient place to tie off the reel, and an auspicious start to our dive. I deployed the SMB, which, unencumbered by a line attached to a spool, careened to the surface, and launched, like a small pink ballistic missile, out of the water beside the waiting Thermocline.  The second dive team — Lee Critchley, Conor Collins, and Colin Miller — were into the water in moments to start their dive.

Water tube boiler and engine parts; screen grab from video survey. Photo by Ewan Anderson/UASBC

Back at the wreck site, Jason and I started the next phase of our dive: a visual survey of the site. Firing up the DPVs, we followed the driveshafts forward from the propeller. The shafts disappear under a jumble of machinery that will need a more thorough survey to sort through. The large water-tube boilers appeared next, standing upright on their fire-boxes about 2-3 m/6-10 ft proud of the seafloor. Patches of the relatively thin steel encasing the boilers had corroded away, revealing intricate tubing that was cutting-edge boiler technology in the early 20th century. Winches and engine parts formed another pile forward of the boilers, beyond which was the relatively featureless expanse of seabed corresponding to what was once the vessel’s hold. About a minute later, we rounded the forecastle which sat upright about 3 m/10 ft high, the foredeck winch still in its original position. We completed our circuit with a straight run back to the stern, spotting the second drive shaft and propeller.

As the second team arrived on the bottom, Jason and I lit up the wreck with our video lights. I wanted to document the visual survey we’d just completed, so I coordinated with Jason to do a re-run at slow speed. He led and illuminated the wreck, while I followed with the DPV-mounted camera and lights. Keeping Jason in frame made for a good scale reference as we slipped slowly past century-old rust and watchful fish. The end of our video captured the other team swimming around the boilers. Conor was taking still photos while the others inspected the machinery and puzzled out what they were looking at.

Jason Cook lighting up the foredeck winch; screen grab from video survey by Ewan Anderson/UASBC

And just like that, it was time to go. Leaving the reel for the other team to collect, Jason and I headed back to the shot line and had the usual brief conversation confirming our decompression plan before leaving the bottom.  The ascent took us back up to the relatively crystal-clear water above 45 m/150 ft. We crossed the thermocline around 15 m/50 ft and completed our deco in 18°C/64° F water and dappled green sunlight. 

Dive teams on deco; from left to right: Jim Dixon, “The Boat Driver,” Jason Cook. Photo by Ewan Anderson/UASBC

The Rediscovery

Back onboard the Thermocline, we all agreed that the first day of diving was a great success. We had identified a wreck and concluded that it was worth diving again; but was this definitely the wreck of the Admiral Knight? We thought so: it is a steam-powered, twin-screw vessel of the correct size.  And we knew the burning hulk was seen by several witnesses drifting in the vicinity of our wreck site in late July 1919. More definitive evidence of the wreck’s identity lies in a closer inspection of the surviving equipment and the cargo. We surfaced with about 10 minutes of good-quality video and some still photos, which Jacques will want to review and comment on.  

The two-hour sail back to the dock, and lunch at the marina pub gave us plenty of time to debrief and discuss the details of our dives. We sketched out the goals for diving the next day, and I included a somewhat ambitious list of items to measure and a plan to create a 3D model of the boilers.

Jason and I were back in the water 24 hours after our first dive on the wreck. The shot line had landed right behind the boilers, so we got to work immediately. This time, we planned to document the boilers using photogrammetry. Issues with camera float arms the previous day meant we were not able to carry as many big lights, so I had the camera while Jason handled most of the lighting.  

Jason Cook preparing gear. Photo by Ewan Anderson/UASBC

The somewhat poor visibility and missing lighting (though we still had a lot of lights) meant we had to get relatively close to the wreck for well-lit photos. And since the boilers don’t cover a very large area, I decided to park the DPVs and kick. In hindsight, the DPVs might have made things easier, but I didn’t notice the current sweeping across the wreck until after the kicking started. I’m not beyond second-guessing myself underwater, but with only 30 minutes of bottom time to set-up and complete the photogrammetry, there wasn’t a lot of time to reorganise and restart the work. In the end, we managed to get about 470 reasonable photos for our modelling project.  

The second dive team, Guy and Jim Dixon, arrived on the wreck a few minutes after Jason and I started taking photos. Guy and Jim had the straightforward task of just enjoying the dive. This seemingly simple job is a common assignment on UASBC dives: divers who are unencumbered with cameras, lights, measuring tapes, and other documentation equipment are free to explore and are likely to notice important features that busy diver-photographers might miss. This team spent some time inspecting two “block” features that I had noticed the previous day; sitting forward of the engines and boilers, the blocks could have been the remnants of the vessel’s cargo, which would be an unusual find because we don’t often see intact cargo on our wrecks. We didn’t manage to solve the mystery on this expedition, and even with Guy and Jim offering detailed descriptions, we’re all still scratching our heads.

  • Rebreather Forum 4

Although there were only a handful of divers who made it down into the wreck in August, dozens of people have contributed their time and energy over the last decade and a half to making these successful dives possible. To dive into the unknown just to see what’s there is one thing, but to dive with purpose and come back with valuable information requires dedicated research and planning. Credit for our success (and the pressure to succeed!) in search for the Admiral Knight is largely due to Jacques Marc and other researchers at the UASBC who laid the groundwork for the project.

There is much more to come. We’ve proven that we can add deeper sites to the list of the UASBC’s potential expeditions. Jacques and other UASBC volunteers are turning to the archives to find more targets. By extending the range of what is possible for the local community, we also open the door to exploring deeper into history. Indigenous peoples have lived around the Salish Sea since time immemorial, as indigenous elders and cultural leaders say, and their cultural inheritance includes documented sites spanning the last 14,000 years. The connection Salish peoples have with the sea around us is undeniable, yet tangible underwater heritage sites other than shipwrecks have barely been explored.

As for the Admiral Knight, any uncertainty about the wreck’s identity may be beside the point. The wreck still makes for a great dive, and although it is relatively deep for most divers, many in our local dive community are qualified – or will be soon – to dive it. It’s worth the effort just to see the intact boilers and the entire vessel’s contents laid out on the seafloor, just as they were 103 years ago. The intact sections of wreck and potential cargo provide opportunities for further study and research as well. 

See companion stories:

Building Community Through Project Diving By Guy Shockey

Introducing GUE’s New Project Diver Program By Francesco Cameli

Dive Deeper

InDEPTH: How to Become an Explorer: Passion, Partnership, and Exploration

Underwater Archaeological Society of British Columbia 

Thermocline Diving 

Marc, Jacques and Warren Oliver Bush (2021) Historic Shipwrecks of the Southern Gulf Islands of British Columbia. Underwater Archaeological Society of British Columbia, Vancouver, B.C.


Ewan Anderson is a professional archaeologist whose work focuses on assessing and mitigating development construction impacts to cultural heritage sites in British Columbia.  A consultant for all levels of government, a variety of industries and Indigenous communities, his expertise is in cultural heritage law, cutting edge archaeological methods and Indigenous peoples’ relationships with archaeology and those who practise it.  

Ewan is passionate about diving – especially when combined with underwater cultural heritage projects.  He is a GUE certified JJ-CCR diver and IANTD certified cave diver.   His diving has taken him around the world, even though everything he needs –  from wrecks to caves – can be found within a few hours of his home in Victoria, on Vancouver Island. 

His professional work and diving almost never mix, for which he is often thankful.  Ewan pursues his interests in underwater photography, underwater photogrammetry, and advocating for conservation of marine environments and underwater heritage, free from the yoke of capitalist overlords. He is a regular volunteer on Underwater Archaeological Society of BC expeditions and has served on the Society’s board of directors since 2018. 

Subscribe for free
Continue Reading

Thank You to Our Sponsors

Subscribe

Education, Conservation, and Exploration articles for the diving obsessed. Subscribe to our monthly blog and get our latest stories and content delivered to your inbox every Thursday.

Latest Features

Trending