Alvin Sub and CORKs

Chapter 6. 

The Alvin Research Submersible and CORK subsea observatories

     In August of 2009 I got one of the best opportunities imaginable for someone in my slightly obscure profession.  I was invited to participate in a 20-day expedition to the Juan de Fuca Ridge hot vent area off the coast of Washington and Oregon.  The cruise would be aboard Atlantis, the mother ship for the famous Alvin research submersible.   I was fortunate enough to be an observer in one Alvin dive on that voyage.  This was literally a chance in a lifetime for me.  Only a comparative handful of people ever get to dive in the Alvin; roughly equivalent in my craft to a space scientist or engineer getting a ride in the Space Shuttle.

     This chapter and Chapter 7 will be devoted to describing that experience and sharing some photos.  Along the way I will fill in some information about Alvin, both what can be found in ocean research literature as well as my own story as a participant.  Also, we will delve into:  why I was there (to help service a CORK, a subsea observatory), some background on just what CORKs are and why they are interesting, and then some inexpert discussions of seafloor hot vents and thermal region with emphasis on the Juan de Fuca Ridge area.  The anecdotes at the ends of both of these chapters come directly from those Alvin-CORK dive events.

Alvin Research Submersible, courtesy WHOI



     DSV Alvin deep submergence manned research submersible .  The story of Alvin goes back to 1964 when the US Navy and Woods Hole Oceanographic Institute combined efforts and funds to design and build America’s first manned research submersible that would be continuously operational and available to dive to great ocean depths.  It would be available most of the time to Woods Hole for routine ocean research.  It also was vital for Navy special projects (like recovering nuclear weapons lost in the deep oceans).  And the sub was used for popular headline research (Alvin was the first manned submersible to investigate the wreck of the Titanic after its discovery by Ballard and Michel in 1985).  I won’t go into much about Alvin specifics and history here because there is a volume of that kind of information online.  I have included a handful of links below and there are hundreds more – Alvin has had a stellar and well-chronicled history.  In this blog article I will describe my experiences aboard Atlantis and Alvin.   

R/V Atlantis, Tender Ship for Alvin



     Atlantis is the 273-ft current mother ship/tender for Alvin.  There have been several others in the almost-50-year history of Alvin.  The photos here were taken aboard Atlantis on my cruise.  The navigation and positioning systems are state of the art.  At the fantail is an A-frame for launch and recovery of Alvin, which is stored in a special hanger when onboard. Atlantis is comfortable, versatile and specifically designed to both support Alvin diving operations and provide space for onboard laboratories for scientists, researchers and engineers who use Alvin for an impressive array of deep ocean dive operations.  Incidentally, the food on Atlantis is the best I have ever had on any the drillships and research vessels I’ve sailed aboard.      



Alvin on deck between dives

      The Alvin submersible is awesome, even almost 50 years after being initially designed and constructed.  I say “initially … constructed” because the sub has undergone continuous minor and major upgrades, redesigns and refurbishments.  It has remained the same sub in principle because it was never totally retired and replaced, but the crew will tell you that there is not one part of the vehicle that has not been replaced at least once at some point in its evolutionary trail.  In 2012-13 the biggest component, the spherical titanium pressure hull was been replaced (from a nominal 8-ft diameter to a roomy 9-ft design) with more interior space, bigger viewports and an upgrade in pressure resistance to allow the sub to go to a rated depth of 6000m (~20,000 ft).  The 8-ft sphere had a depth limit of 4500m (not quite 15,000 ft.).  See Ref. [3].



Alvin being launched with A-frame



     Here are the basics.  Alvin is free-swimming (no tether to the mother ship).  It runs on batteries – not quickly but underwater it has plenty of maneuverability.  It holds a crew of three (pilot plus two observer scientists or engineers, or politicians when they are in PR mode).  Its interior is atmospheric; there is no pressurized gas for breathing; a so-called short-sleeve dive environment.  Despite the chilly temps of the deep ocean Alvin does not have a heater system for personnel comfort – you dress warm and let the onboard electronics byproduct heat keep you reasonably cozy.  Dives can be of any length up to a day or two in theory, but there is limited clean air and battery power capacity so typical dives run from morning to evening (8-12 hours).   The launch and recovery crews on Atlantis greatly prefer that those operations occur in daylight.  

    The interior air is rebreathed by the occupants after being scrubbed by a CO2 removal system – it works, but after 4-5 hours does not smell like a day on the prairie among the wildflowers.  There is no bathroom – pee bottles are provided (I complained that the opening on mine was not large enough in diameter but this joke is so old to the veteran pilots that I didn’t even get a polite laugh.)  The interior is extremely cramped for three large men.  The photos here don’t really give you the entire feel.  

Me, inside Alvin.  Photo taken with a fisheye lens
that makes things appear a lot roomier than they
are. Note the legs of the photogrpaher across mine.
My viewport is near my right shoulder.



Viewing from within the sub is either through three tiny acrylic viewports (see the photo of one of the conical viewports windows removed for inspection and cleaning).  Or, you can use the terrifically nice color video cameras on the top.  Each crew member had control of one of the cameras and we could see any of the images selectively on laptop screens mounted near our heads.  Vision in the total darkness of the deeps (below a few hundred feet) was possible because of lights mounted on the roof of the sub.  Onboard video recording equipment captures every second of the video work on permanent tape or solid state memory.  You can see a lot more with the pan, tilt and zoom characteristics of the video cameras but there is nothing like peering out one of the view ports to get the feeling that this is real, I am really at the bottom of the ocean.




Acrylic viewport, the small end
 is what you see inside the sub

       Communications between the sub and Atlantis is via state-of-the-art underwater telephone gear.  When I was in the Navy in the 1970s such communications to or from submarines was under development but still technically impossible on a practical basis – even for the Navy.  The comm quality to and from Alvin were stunningly good – better than most cell phone calls.  Navigation was also impressive.  Thanks to some previously emplaced seafloor transponders in the area where we were diving on the Juan de Fuca Ridge both Alvin and Atlantis had full time position data for sub, mother ship and critical seafloor objects, accurate to a meter or two.  There was no chance of getting lost in the sub even with visibility limited to a couple dozen meters at best – when the lights were on.

     CORKs.  We were there on my expedition to inspect and service four CORK installations located at depths ranging from 2606 to 2658m (8550 to 8720 ft).  So, what is a CORK?  It is a subsea observatory and requires a little backtracking to explain.  When the JOIDES Resolution drillship drills a hole in the seafloor for scientific core sampling and other downhole measurements they have two options on how to leave the hole:  abandon and let it collapse back to nothing, or install casing (steel pipes) to hold it open indefinitely and top it with a steel re-entry cone structure that sits on the seafloor.  The re-entry cone is 14-ft diameter roughly conical structure (actually they are easier to fabricate and assemble as 8-sides virtual cones).  They allow the drillstring to be reinserted into any already-drilled and cased hole for further work, and include a set of seats in the throat to allow landing casing hangers that hold up the casing string(s).  The existence of a drilled hole with casing and a re-entry cone is referred to as a “legacy hole”, meaning the subsea geological research organizations consider it suitable for ongoing research through repeated visits and sometimes novel new research approaches.   It provides access to the world under the seafloor in manner similar to a deep mine on dry land that might be considered an access avenue for continental deep earth research.  Some years after re-entry cones had been installed in scores of places on the seafloors of the oceans all over the globe, a clever group of scientists lead by doctors Earl Davis and Keir Becker suggested the novel concept of a sub-seafloor observatory using legacy re-entry holes.  (See Ref [5]).  Their idea was to install strings of monitoring and sampling instruments into the re-entry cones and down the boreholes and leave them over long periods to monitor changing sub-seafloor conditions.  This is literally something that was not possible before application of this concept.  The device that would land and seal itself in the throat of the re-entry cone to accomplish this was initially called a Re-entry Cone Seal and Feed-thru.  That name was unwieldy, so my engineering group, tasked with design, construction and testing of the new mechanism just called it a “cork” for shorthand.  That became CORK in all caps, but it is not an acronym for anything, although later on people tried everything they could to force fit some phrase to match the letters.*  The image above is a depiction of a typical re-entry cone and 3^rd generation CORK.
     CORK subsea observatories should not be confused with the NEPTUNE Program, a broader initiative for creating and maintaining sophisticated observatories on the seafloor.  NEPTUNE is being pursued by scientists from the US and Canada.  One of the keys to NEPTUNE is that the undersea measuring systems will be tied to cables or other real time data transmission systems. See Ref [6] for more information.  There has been much discussion of tying CORK observaories into the NEPTUNE undersea network at some point in the future.

     The hot geothermal regions of the east flank of the Juan de Fuca Ridge (JdFR) encompass both hot vents and areas without vents but where the seafloor is significantly hotter than normal.  Four sites in the non-vent areas were drilled and four holes were designated as CORK legacy holes with re-entry cones and casing plus CORK installations added at the time of drilling or later.  CORK installations include batteries that power the sampling systems, data storage memory modules, and sampling strings that land in the CORK and extend thousands of feet into the hole in the seafloor.  Batteries, memory modules and sampling devices must be swapped out and/or downloaded periodically to complete the science measurement operations.  This can be done by the drillship, although that is awkward and generally not high in the drillship priority lists.  Hence, the CORK installations are more commonly visited for service calls by submersibles, either manned, like Alvin, or remotely-operated ROVs, like Jason.

     One of the CORKs at the JdFR was observed during one submersible service call to be vigorously venting hot water around the outside of the re-entry cone and alongside the seal between the CORK and the re-entry cone throat.  This meant that the seal between the CORK and the re-entry cone was bypassed.  That seal is essential to isolate the downhole fluid environment from the open ocean.  Consequently, the JOIDES Resolution returned to the site and pumped cement onto the re-entry cone, onto the mudmat and over the surrounding seafloor a few feet in every direction in hopes of sealing off the zones between the upper casing and seafloor as well as between re-entry cone and CORK.  This was something like pouring a concrete patio through slender pipes from 8500 feet overhead.  On our Atlantis-Alvin cruise one of our missions was to inspect the new cement-seal job that had been completed several weeks earlier.



CORK with cement job.  Note sub work basket
in foreground and manipulator arm at right.  The
14-ft re-entry cone lip almost fills the image. The
 holes with "meringue" are what is visible of the
 CORK sub/ROV platform after cement was added.
  Note small octopus on left edge of platform.

The photo here show what we found.  The cementing job was not successful in sealing the hole around the re-entry cone or plugging the seal zone between re-entry cone and CORK.  You can see that the outflow of hot water from the seafloor was so powerful that it simply displaced the cement out of its flow path and held it there until the cement hardened –which was probably quickly at those temperatures (something like 140 deg F).  A lot of the cement ended up on the CORK sub/ROV platform.  It has holes that allow the CORK to be lowered initially to the seafloor to land in the cone without too much parachute effect underwater.  Note the shape of the solidified cement around the holes in the CORK platform  – almost like meringue on a lemon pie.  Amazing.
 

     Next chapter – details of my Alvin dive, pictures and comments about seafloor creatures in the region and some lore about hot seafloor vents.

*Some official reports now state that CORK stands for Circulation Obviation Retrofit Kit, which was a tongue in cheek after-the-fact appellation and sounds frankly ludicrous to the original CORK designers.

[1]  Wikipedia page chronicling Alvin history

http://en.wikipedia.org/wiki/DSV_Alvin

[2]  Woods Hole webpage about Alvin

http://www.whoi.edu/alvin/

[3]  Excellent article from Gizmag on Alvin history and recent upgrade

http://www.gizmag.com/dsv-alvin-submarine/27674/

[4]  News story about Alvin upgrade and return to service in 2013

http://science.nbcnews.com/_news/2013/05/30/18631695-upgraded-submersible-alvin-readies-for-more-dives?lite

[5]  One of dozens of CORK papers by Dr. Earl Davis and Dr. Keir Becker

http://www.odplegacy.org/PDF/Outreach/Brochures/Greatest_Hits2/davis.pdf

[6]   NEPTUNE Undersea Observatories
www.neptune.washington.edu and www.neptunecanada.ca

Anecdote:  “The Little Purple Octopus”

     In this chapter’s story I tell of my experiences diving in the manned submersible, Alvin, to service the CORK seafloor observatories at the Juan de Fuca Ridge offshore Washington and Oregon.   Atlantis-Alvin has visited there to inspect and service those CORK installations more than 16 times.  As some of the earlier pictures indicate the CORK structures turn out to be attractive habitat options for many of the locals, including a species of purple octopus.  

Small octopus who has taken residence on a CORK



The little guy (or gal) at the left is a prime example.  Those creatures had been spotted on every dive to these CORKs by the various submersible pilots and observers.  One octopus in particular took up residence near the top of the CORK assembly, as you see in this photo.  He became quite familiar to the dive crews and on one series of dives was participant to a bizarre incident with Alvin.  (I cannot be sure if this is the same specific octopus because this picture was taken during my one dive opportunity, one or two years after the incident that was described to me by the Atlantis crew.  On the other hand this may be the same individual; who knows how tough they are or how long they live.)

     On the expedition to the Juan de Fuca Ridge CORK observatories of a year or two earlier the various Alvin dive crews had all noted the little purple character and taken his picture.  He seemed to be content in his new home and not very intimidated by the presence of the (to him) huge, noisy, brightly lit submersible with its scary looking manipulator arms.  As the diving days went by the dive crews decided an experiment was in order with the octopus.  They decided to try feeding him, don’t ask me why since he obviously wasn’t suffering from malnutrition.  Treating him like a pet, I guess.

     Nonetheless on the next dive the Alvin crew took a few bits of raw shrimp down in the work basket to offer to the octopus.  The found him in his now-normal place high up on the CORK where Alvin could safely be maneuvered into position for one of the manipulator arms to reach out with a shrimp morsel to see if he was interested in a snack.  The octopus did not respond as expected, but maybe as any tiny creature would respond under such intimidating circumstances.  He ignored the food tidbit and instead grabbed on to the manipulator arm with one of his tentacles.  Seeing the problem the Alvin pilot gently withdrew the arm but, oh-oh, the little guy refused to let go.  And with his other tentacles he held fast to the CORK structure.  What to do now?  The pilot had no choice but to continue pulling the mechanical arm back slowly hoping the octopus would get the hint and let go.  But no, the octopus held on with all his might to both manipulator arm and CORK structure until the crew described his entire body as stretched to the apparent limit.

     Then his tentacle attached to submersible’s arm just snapped off.  Steel and titanium hardware powered by hydraulics are a lot stronger than little subsea creatures and their physiology.  The sub completed the dive mission and returned to the surface feeling really bad about the entire incident.  No word on whether or not the little purple octopus arm was still attached to manipulator when the sub was recovered onboard the Atlantis. 

     But that is not the end of the story.  On the next Alvin dive to the same area the sub suffered a mechanical failure of the same manipulator arm that got tangled up with the octopus.  During a routine operation it suddenly fell off the sub!  Truly.  For no evident reason.  This had never happened before in the dive history of Alvin, although, in fact the manipulator arms are designed with weak links where they are attached to the sub so they will rip loose in an emergency if the sub gets ahold of something on the bottom and then cannot release the arm.  It is a safety feature that had never been necessary in the past 40 years of Alvin service.  In this instance the arm fell off and landed on the seafloor and the sub shot towards the surface because the sudden loss of the weight of the manipulator arm badly upset the delicate buoyancy balance that allows Alvin to “hover” gracefully at any depth.

     No lasting damage was done to Alvin.  The sub and crew returned to the surface safely.  The dropped manipulator arm was easily recovered by Alvin during the dive on the next day.

     No one knows if the little purple octopus was mortally wounded by having one tentacle amputated.  Maybe that variety of octopus can successfully grow back a lost arm.  But the incident has gone down in the lore of the Alvin as … The Revenge of the Heptopus!