Ice Stories: Dispatches From Polar Scientists » Doug LaVigne http://icestories.exploratorium.edu/dispatches Mon, 15 Nov 2010 20:40:36 +0000 http://wordpress.org/?v=2.9.2 en hourly 1 Bad Weather and the JR http://icestories.exploratorium.edu/dispatches/bad-weather-and-the-jr/ http://icestories.exploratorium.edu/dispatches/bad-weather-and-the-jr/#comments Thu, 27 Aug 2009 00:13:17 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1788 JOIDES RESOLUTION, ON THE BERING SEA-- One of our readers there posted a great question in response to my posts regarding the incoming Typhoon Vamco approaching us from the South. I consulted the Captain and...]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– If you aren’t familiar with our FaceBook page, you should sign up right now and become a fan of the JOIDES Resolution. One of our readers there posted a great question in response to my posts regarding the incoming Typhoon Vamco approaching us from the South. I consulted the Captain and he gave me a great response, so I posted it. In fact it was good enough to repost here. So here you go…


Typhoon Vamco

From our fan Robert J Palmer: “I have a quick question I hope its not rude, but what would be the maximum “swells” and “winds” that the JR would handle “safely” ? The drilling rig alarms me as a probable target to the wind.”

The extreme forces of nature in our vast oceans can be pretty daunting at times but if you consider a bottle with a good cork in it, the bottle will float forever unless damaged and water is allowed to enter. So, just like the bottle we must ensure that there is no water ingress in the JR by ensuring that the numerous weather tight doors and hatches are maintained in good condition and seal properly.

Next we must ensure that heavy equipment is properly secured and doesn’t move with the movement of the vessel as this could cause injury to personnel or damage to the watertight integrity of the vessel. We must ensure our propulsion and steering is in good shape because loss of control in a storm would cause the vessel to turn beam to the seas and roll very violently causing equipment to break loose and damage to occur.

To the drilling tower or derrick. Yes it is high and acts like a sail on a yacht heeling the vessel over to one side. But the JR was constructed to be able to withstand winds of 100 kts when intact or 70 kts when damaged with one compartment flooded.

Tropical Revolving Storms, also named Hurricanes, Typhoons or Tropical Cyclones depending on your location can exceed 150 kts at times and are extremely dangerous on the high seas. Fortunately for the modern mariner we have excellent tracking predictions and weather forecasting. Also the tropical storms are small and slow moving weather systems so they are generally easy to avoid.

The main problem with the JOIDES Resolution in heavy weather is our people are not hardened seafarers and there is a large amount of delicate scientific equipment which we do not wish to damage even slightly.

We can put figures on the vessels movement roll pitch & heave which we can safely “work in”. But to your quick question. What would be the maximum “swells” and “winds” that the JR would handle “safely”? She is a well built vessel and immensely strong, so let’s just say “with the very experienced crew we have on board, I am happy to sail to the ends of the Earth on her”.

Alex Simpson
Captain
JOIDES Resolution

*****

And so as to not cause unnecessary alarm, the Captain offered this weather update today as we make our way to Japan:

Vamco is moving slower than predicted. Although it is fast losing its status as a Typhoon, it is actually set to intensify again as a major North Pacific depression with associated storm force winds as it moves into the Bering Sea. We set out on our original course when we left the site early this morning. We have now adjusted our course towards Kamchatka to avoid the worst of the storm and should enjoy favorable weather for the next few days. There is no delay associated with this course change.

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Sunset and Beacon Catch http://icestories.exploratorium.edu/dispatches/sunset-and-beacon-catch/ http://icestories.exploratorium.edu/dispatches/sunset-and-beacon-catch/#comments Tue, 25 Aug 2009 21:21:20 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1773 JOIDES RESOLUTION, ON THE BERING SEA-- It’s amazing how after two months on a boat with the same people day in and day out how your nerves start to get a little rattled. Not that we aren’t getting along, it’s just the lack of something new...]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– It’s amazing how after two months on a boat with the same people day in and day out how your nerves start to get a little rattled. Not that we aren’t getting along, it’s just the lack of something new. The slightest hint of something bad or good happening at home and I start to get a little frustrated that I am not there to deal with things. Add a bad video camera into the mix and you might have a really bad mood.

The camera decided to reject the disk that was in it with about 30 minutes worth of video I had shot over the last few days. Needless to say I was a little annoyed.

Luckily the Logging Engineer talked some sense into me and I didn’t see how far I could throw the camera into the ocean. Clay has all sorts of Sony video processing software on his computer, so he took the disk to see what he could salvage. The bad news was that nothing on the disk was recoverable, but the good news was that I was able to reformat it and continue my video diary. Thanks Clay! Mood salvaged!

We had just greeted the arrival of the last core on deck for the expedition, and everyone’s spirits were high. My mood had picked up considerably after I realized I could once again take more video clips. So after figuring which files were lost I decided to enjoy the last sunset on site, and depending on the weather, possibly the last visible sunset of our expedition. Turns out I was not alone.

We watched the sun slowly sink in the distance. Partly obscured by clouds, there was no green flash to be seen. But that didn’t stop our enjoyment. The sky flared beautifully as the last of the light faded beneath the blue horizon. It was symbolic of the sun setting on our trip. The days are few before we hit Japan. And then we go our separate ways.

And to add to the beauty of the evening, the beacon was coming up at the same time. So we were able to watch its recovery. The beacon is a device that emits a high frequency ping to let the JR know where we are as a redundant back up to the GPS system. It is dropped to the ocean floor when we first arrive on site. Before we leave each site the beacon releases the weight it is attached to, and rises to the surface and the talented crane operators and crew recover the beacon so it can be used again. It was a quick and flawless recovery.

Now I need to get some rest and prepare for the transit home. The work here is not done, but we are one step closer.


Sunset over the Bering Sea.
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Driver’s Ed in the Bering Sea http://icestories.exploratorium.edu/dispatches/drivers-ed-in-the-bering-sea/ http://icestories.exploratorium.edu/dispatches/drivers-ed-in-the-bering-sea/#comments Sun, 23 Aug 2009 17:03:07 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1760 JOIDES RESOLUTION, ON THE BERING SEA-- Wrapping up the second to last site might otherwise be an uneventful, if somewhat relaxing occasion. But today was a bit different....]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– Wrapping up the second to last site might otherwise be an uneventful, if somewhat relaxing occasion. But today was a bit different. Most of the other transits have happened at the end of my shift, when I was really busy or fairly late at night. But today the transit happened at about 1:30pm, and it was a bright sunny day. And more importantly, Captain Alex let me drive.

There are a few things to do when we get underway, and I only handled the manual steering portion. We directed our rudders so that we were facing into the wind, and slowly increased our speed, keeping it under 3 knots (about 0.8 knots to be exact). It takes time for the thrusters to warm up and for the ship to get into the transit mode after sitting relatively stationary for several days. Going slow gives things some time to adjust and prevents us from damaging the ship (and more importantly, the folks working in the engine room when things start going wrong).


That’s me behind the wheel.

Basically I had to watch our heading and adjust to keep us headed in the right direction, and eventually get us onto the new heading of 353 degrees. We are headed to the farthest point North we are visiting. Since we are going above the 60th latitude, we are going into the Arctic Ocean. This is particularly interesting because in a few short months the ship will be headed to the other extreme when it reaches the Antarctic.

Eventually we turned the ships controls back to automatic, and she is already settling in at NAV1-B, soon to be site U1345. We made great time at almost 12 knots the whole way. The typhoon Vamco is headed our direction after moving away from Japan. Amusing that it will drop out of the news now that it doesn’t threaten land, but it still poses a threat to us. Hopefully it will die down before we start our journey south to Japan early next Tuesday morning.

Everyone is tired and yet excited to be done. Preparations are beginning to deal with cleaning up and packing up the ship to make ready for the next expedition. There are customs forms to fill out and arrangements to be made for when we get to Japan. Of course it will be nice to have a bed that doesn’t rock again.

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High Flying Fun http://icestories.exploratorium.edu/dispatches/high-flying-fun/ http://icestories.exploratorium.edu/dispatches/high-flying-fun/#comments Wed, 19 Aug 2009 23:31:08 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1755 JOIDES RESOLUTION, ON THE BERING SEA-- It was remarkable how many people showed up for the kite contest today. Before long the heli-deck was packed....]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– It was remarkable how many people showed up for the kite contest today. It started as a trickle of people as folks wrapped up what they were working on in the labs and on the drill floor, and before long the heli-deck was packed.


There was one rule on kite day: fly your kite.

The judges wandered around checking everything out and taking notes. Several categories had been announced in advance and on the spot creativity could result in additional recognition. The variety of kites was pretty impressive, especially considering the scarcity of building materials to make them.

Aside from the hazard of crossed lines and heavy kites sometimes flying hard into the ground, it was great fun. Captain Alex broke things up by launching a flare into the midst of the kites! At one point a pod of whales showed up on the starboard side, but at the front of the ship. Not sure if they were Minke whales or orcas though. They were kind of far off.

It was the most pure fun we’ve had in quite a while. Everyone’s energy was high. I think the key to making us happy here on the ship is having something different to do. Variety indeed seems to be the spice of life on board the JR. It wasn’t the prettiest of days, but it was perfect to watch some of the best kites disappear into the gray cloud cover.

I wish I had more to say about it, but I am exhausted and ready for some sleep. Hope you enjoy some videos of our kite adventure. So here are the winners if you don’t want to watch the whole video! Check out more photos on the JOIDES Resolution Facebook page.

* Most Dangerous Kite – Jamie Smidt and Carlos Alvarez Zarikian
* Most Acrobatic Kite – Rey Villa
* Smallest Kite – Doug LaVigne
* Most Spectacular Crash – Bill Mills
* Highest Flying Kite – Jerry Mayuga
* Most Colorful Kite – Kelsie Dadd
* Most Creative Kite – Christina Ravelo
* “You must be joking?!?” – Laura Wehrmann and Emily Walsh
* Most Innovative – Hirofumi Asahi and Makoto Okada

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Sampling http://icestories.exploratorium.edu/dispatches/sampling/ http://icestories.exploratorium.edu/dispatches/sampling/#comments Sun, 16 Aug 2009 16:54:45 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1746 JOIDES RESOLUTION, ON THE BERING SEA-- Cores come in 24 hours a day, 7 days a week when we are at a drilling site. They are processed round the clock by the technicians, and then the scientists begin...]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– Cores come in 24 hours a day, 7 days a week when we are at a drilling site. They are processed round the clock by the technicians, and then the scientists begin the process of whole round testing. After they’ve had a chance to warm up to room temperature we split them into halves. One half is imaged, described and archived. The other half is the working half. What happens to it? In this blog I’ll try to describe the story of the working half.

After being cut, the halves are split up. The working half is placed in marked trays that are labeled 1-7 and CC for the core catcher. They are identical to the trays on the description table, but these are where the scientists get their hands dirty and really go to work. Each site (and each hole for that matter) is different. Depending on the areas of interest for the scientists or possible information we might find at a particular site and depth various requests are made. It is the job of the Staff Scientist to assemble all of those requests with the input of the sampling committee which includes the Staff Scientist, the Co-Chiefs and the Curator. The finished product is the sampling plan.


The sampling plan is the blue print for what the scientists take from the working half of a core.

Posted near the sampling table, this plan is the blue print for what the scientists take from the working halves. Samples range from toothpick scrapes, plugs, wedges, scrapes to mini cores. Microbiologists often take whole round samples (these are taken on the catwalk before the properties have a chance to change). In hard rock they can take what are called slabs. Drop stones can be taken directly out of the working half.


A variety of tools are used to remove the samples, from spatulas to syringes.

The samples are sealed in various containers and some are kept in freezers or cold rooms to keep any chemical changes from occurring. Some of the samples are tested or studied on board, but many are sent to the scientists at their home labs.


Sealing samples.

After the samples are taken, the spots disturbed by sampling are marked with either foam inserts or plastic dividers marked for the science they are used for (ex: PAL for Paleo, PP for Physical Properties). The remaining core material is packaged and labeled in special “D” tubes just like the archive halves in case more detailed sampling is requested post cruise. The “D” tubes are packed into boxes to eventually be shipped to College Station where they are hermetically sealed and eventually stored by the shore based curators.

Here is a quick clip of me sampling with David Scholl, one of the physical properties scientists in Expedition 323:

Hopefully that gives you some insight into the sampling on board the JR. Soon I’ll show you some specific sampling and testing that is done with the core material.

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Cutting the Cores http://icestories.exploratorium.edu/dispatches/cutting-the-cores/ http://icestories.exploratorium.edu/dispatches/cutting-the-cores/#comments Tue, 11 Aug 2009 23:13:13 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1744 JOIDES RESOLUTION, ON THE BERING SEA-- Every core that arrives on the JR has to be split into two halves at some point in the process. Much of the information contained in the layers of mud and rock is...]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– Every core that arrives on the JR has to be split into two halves at some point in the process. Much of the information contained in the layers of mud and rock is damaged due to the invasive nature of the drilling process. To get a clean view of the core as it looked in the ground we must look at the innermost portions of the core. This means cutting it in half. Since cores can come in all consistencies, from soupy mud to hard rock. That means the technicians need to be prepared to cut a wide range of materials that come up in the core liners.


The core splitter.

The majority of the cores on Expedition 323 are mud cores. They require a straightforward procedure to cut them. The plastic core liners are placed on the splitting table and on a grooved track. The track has an motor controlled cutting tool that consists of two hooked razors that split the core liner, but are set at a depth to cause the least damage to the mud in the core. In addition to these razors, there is a thin wire that is held taught and sliced down the length of the core. It works like a big cheese slicer. After the entire liner and end caps are cut, a good tap on the table next to the splitter usually separates the core cleanly into halves. Stickier sediments may cause the halves to cling together, but a small squirt of water or even manually moving the parts with a spatula will cause them to fall apart. This video gives you a good idea of how the process goes.

We’ve been lucky enough to have some hard rocks recovered at one of our sites as well, so I was able to look at the process for them as well. First the pieces of core are cleaned of debris caused by the drilling. The edges of the core may have residue left over from the very physical nature of the coring. After the pieces are cleaned up, they are compared to one another to find out if they are continuous but broken pieces, or if there are gaps. If there are gaps plastic markers are glued in the casing to let those who observe the cores later know what was together in the ground. Often tool marks on the outside of the core can be matched up to give a definite idea of how the pieces were assembled. If the pieces are present, but might crumble or move during the cutting, a quick application of some plastic shrink wrap does the trick to hold them in place for the cutting.

Next the reassembled core is placed in the same groove as the mud cores, but the splitter blades and wire are replaced with a diamond cutting wheel assembly. The blade is slowly moved down the length of the core slicing through the hard rock. It is a noisy and dusty process. Afterwards the halves are carefully separated and cleaned to remove any dust created during the cutting. Afterwards they are left to dry, and the various pieces are labeled with tags glued onto their surface.

Hopefully you have a really good idea of how all of this works now! Next the cores go to the sampling table.

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Video Tour of the JR http://icestories.exploratorium.edu/dispatches/video-tour-of-the-jr/ http://icestories.exploratorium.edu/dispatches/video-tour-of-the-jr/#comments Mon, 10 Aug 2009 01:23:14 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1743 JOIDES RESOLUTION, ON THE BERING SEA-- Drilling is going very smoothly on site U1343. We are almost done with hole C at this site. If things continue...]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– Just a quick update to let you know how things are going. Drilling is going very smoothly on site U1343. We are almost done with hole C at this site. If things continue we should have enough time to get in two more site before we head to Yokahama. Pretty exciting, as the opportunity to find out more of the formational history of the Bering Sea is really close. I expect that the information we’ve already gotten will be amazing when all the pieces are put together.

But for tonight let me leave you with a few more links to some videos I’ve made:

Another video tour of the JR. During the filming of the prior clip of the F-deck, we spotted a cargo ship off the port side. This is what happens any time something different happens, be it whale, seal, porpoise, cargo ship, sunset… anything.

A walking tour to the bridge deck from the F-deck. We had to ask a question of Captain Alex, and I’ll see if you can guess the answer: How far can you see out on the horizon from the main deck? From the Bridge deck? Maybe I’ll get the Captain to explain how he arrives at his answer to this question on video later! He got called away to important business. You may notice there is a lot of magic on this ship…

This is the place where the cores first enter the labs. Lots of testing, imaging, poking, prodding and sampling take place on this deck. I’ll get into more detail soon, and show some of the indigenous scientists in their natural habitat.

A quick interview with Ivano Aiello, one of the sedimentologists on board the JOIDES Resolution for Expedition 323. He explains a bit about one of the things we are looking at (micro fossils in the sediments), and how they help us understand paleoclimate.

Sedimentologist Beth Caissie shows off the Core imaging camera and explains a bit about cleaning up the cores before making these images. Taken on the JOIDES Resolution during Expedition 323 to the Bering Sea.

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The Mystery of the Exploding Cores http://icestories.exploratorium.edu/dispatches/the-mystery-of-the-exploding-cores/ http://icestories.exploratorium.edu/dispatches/the-mystery-of-the-exploding-cores/#comments Tue, 04 Aug 2009 16:42:28 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1733 JOIDES RESOLUTION, ON THE BERING SEA-- Why do some cores explode? One of the problems we’ve had on this expedition is that some of the cores are a bit gaseous. As you go to the sea floor and below it, the pressure from the water above is tremendous...]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– Why do some cores explode? One of the problems we’ve had on this expedition is that some of the cores are a bit gaseous. As you go to the sea floor and below it, the pressure from the water above is tremendous. Styrofoam coffee cups dropped to the sea floor come back a fraction of their original size. Why is that?

Well, the reason is the pressure forces the gases to decrease in volume, and Styrofoam cups are full of pockets of air. That same air insulates your coffee from the air in the room, and keeps it warm longer.

Those of you who know about Boyle’s Law should remember that if temperature stays the same, pressure and volume are inversely proportional. So assuming the temperature at the bottom of the ocean was constant, we know the pressure is really high, so any gases present are super compressed, so much so that they are dissolved into the water. Think of the gas in a can of Coca Cola. It is dissolved in the can, and held in place by the pressure. If you don’t believe me, try dropping a can of Coke on a hard floor. Just don’t do it in my house! It could get very messy. When you open the can (or it pops open) the gases lose pressure, their volume increases proportionally… and you end up with a big mess wherever you opened the can.

Now at the bottom of the Bering Sea, it happens to be pretty cold. Much colder than it is at the surface. If you know about Charles’ Law you should know that if the pressure is constant, then the volume of a heated gas will expand.

Maybe you can see where I am going with this. In a very short time, we take a core that is under tremendous pressure, in some cases full of dissolved gas, and bring it up to the surface where there is significantly less pressure and bring it up to room temperature. Think a can of Coke outside on a hot day. At least where I live, it is a bad idea to leave unopened cans of carbonated drinks in a hot car. Trust me, the interior of my second car served as a painful reminder of this until I sold her.


To release the pressure in the core, technicians drill holes in the core liners.

So that’s why the cores explode. To combat this, the technicians drill holes in the core liners (the plastic sleeves the cores are recovered in) to release the pressure. They try to minimize disturbing the core, but leaving the gases to build up volume can be explosive.


An amusing byproduct of the holes are the “worms” of sediment that escape. As with any sample, these are collected, documented and saved.
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Fire Drills and Emergency Rations http://icestories.exploratorium.edu/dispatches/fire-drills-and-emergency-rations/ http://icestories.exploratorium.edu/dispatches/fire-drills-and-emergency-rations/#comments Sun, 02 Aug 2009 21:08:06 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1729 JOIDES RESOLUTION, ON THE BERING SEA-- Today started with an early fire drill. Everyone reported to their assigned life boat stations with our emergency gear on...]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– Today started with an early (actually 10:30am our time) fire drill. Everyone reported to their assigned life boat stations with our emergency gear on. Hard hats, safety goggles and life vests are required every time. While we did that, the fire team (members of the crew specially trained to fight fires) met in the laundry area to run through a mock fire scenario.


Captain Alex

Captain Alex talked with our life boat group, and explained the importance of the immersion suits, and that we are not expected to wear them if we are going into the life boats. Apparently there have been cases of individuals using them in life boats getting overheated and suffering from other problems as well. And there isn’t a whole lot of room to remove them when you are inside the life boat.


The life boat rations, in a lovely display the catering guys put together for us.

Since the life boat rations were going out of date and being replaced, we got to sample them at dinner. They have a pleasant smell that reminds me of coconut. The taste however is more like cardboard. And they are very dry. I hope there is a lot of water in the life boats if we need to use them!

We are finishing up at site U1341 tonight, and heading out to the last site on Bower’s Ridge. This one is the shallowest of the three on the ridge at 850 meters, so the pipe should be in place by morning, and it could be a quick turn around for each core recovery. We’ll have to be on our toes to get everything processed.

By popular demand I am posting links to some video blogs I’ve been putting together to document some of the living and working spaces on board the JOIDES Resolution. It is a very informal tour, originally intended for a small audience, but since so many people liked them there, here they are!

This is a tour of my stateroom:

This is a tour of the main deck living accommodations:

This is the rest of the main deck areas, laundry and galley:

This is the lower tween deck, and the entertainment facilities there:

And this is the forecastle deck, labs and office space:

I hope you enjoy these, and if there is something you want to see, let me know!

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How Do You Stop the Motion of the Ocean? http://icestories.exploratorium.edu/dispatches/how-do-you-stop-the-motion-of-the-ocean/ http://icestories.exploratorium.edu/dispatches/how-do-you-stop-the-motion-of-the-ocean/#comments Tue, 28 Jul 2009 16:58:14 +0000 Doug LaVigne http://icestories.exploratorium.edu/dispatches/?p=1725 JOIDES RESOLUTION, ON THE BERING SEA-- The JOIDES Resolution is equipped with some of the best devices available to do her job. She is designed to move quickly on the ocean carrying a great deal of equipment and people to remote locations, and the ocean can be a rough place...]]> ABOARD THE JOIDES RESOLUTION, ON THE BERING SEA– The JOIDES Resolution is equipped with some of the best devices available to do her job. She is designed to move quickly on the ocean carrying a great deal of equipment and people to remote locations, and the ocean can be a rough place. But a problem arises when you are on the ever changing surface of the ocean and you are trying to drill a hole thousands of meters below the surface. How do you hold the drill steady when it is mounted to a ship that moves with the flow of the water? That is today’s topic.


The JR.

As we stop in one spot to begin drilling, the ship’s dynamic positioning computer system goes to work. The two thrusters in the aft of the ship are joined by another ten placed around the ship. Running constantly once we are in place over our location, they keep us steady. The beacon is a device that is dropped to the ocean floor to aid in maintaining our location. It is somewhat redundant with the ships other navigational equipment, but it is there just in case we there are any failures.


Deployed thrusters on the port side, forecastle deck, help keep us steady.

In addition to the thrusters, the derrick has what are called heave compensators. Most drilling problems are related to variations of the composition of sediment being drilled, and or problems clearing out the hole. When you add a rocking ship into the equation, things could get complicated. To combat this, the JR employs both passive and active heave compensation. The passive compensator is a reactive air cushion that reduces vertical movement. But since it has to overcome friction in the seals, it reacts better in rougher seas. In six foot seas it keeps the drill steady to about 3 feet relative to the sea floor, while in twelve foot seas it can keep it within around 2 feet relative to the sea floor. Pretty impressive considering this is several kilometers beneath the ship! The active heave compensator uses hydraulic power to overcome that friction, and can improve the heave compensation to within about 4 inches of motion at the rig floor. How’s that for calm?


Heave compensators reduce vertical movement.

And now this positioning equipment is so precise that a new problem has emerged. Tides. Tides vary according to the position of the moon and sun, because of the changing gravitational forces they exert on the oceans. In the past it was difficult to see these effects, and in short time periods you’d never notice a difference. But now due to the quality of heave compensation and the accuracy of the depth measurements, tides can be seen affecting drilling depths when we are drilling at one site over multiple days. Now that’s pretty amazing. One of the new things we are looking at on this expedition is tidal charts for this area, in an attempt to predict and account for the variations in ocean depth at our location. Maybe this will play a part in all future IODP drilling projects?

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