Concordia Update: More investigative tools

Authorities have recovered the Voyage Data Recorder (see previous post) so the ship's onboard data will be emerging soon.

Meantime, Quality Positioning Services BV has put together a vessel track from the navigational info that Concordia was transmitting in its last hour. Check it out:

The initial allision happens just short of a minute into the video. You might well wonder how it's possible for anyone to put this together when the VDR data and shore radar records haven't been released yet. It's because under ship-safety treaties, ships like the Concordia must carry an Automatic Identification System (AIS) transmitter, which sends a constant update of the ship's position, speed, and course. ("Course" reflects the direction the ship's bow is pointing, regardless of which way the hull is moving.) 

Ships trade the AIS information with each other as a collision-avoidance system, supplementing their radar sets.

AIS information is also captured on shore by the Vessel Tracking Service and AIS base stations. That's the data stream that QPS used in preparing the track video.

Here's a link to a PDF document explaining the company's methodology. QPS notes that the ship first struck the rocks at a speed of 15 knots. Here's one of those boulders, which the ship broke off and carried away, until it returned to shore for the last time:

Self-correction on the ship's propulsion: In this post I wrote that the Costa Concordia might have used thruster pods for propulsion. (Thruster pods, also called azipods, are swiveling units that house electric thrusters, mounted under the hull.)  Rather, Concordia used a variable pitch propeller, powered by marine diesel engines running most of the time on heavy fuel oil (HFO) that's so thick it only flows when heated. Here's my Rena post on HFO and how it differs from diesel fuel. 

Photos of the hull on its side, while confirming that Concordia didn't have azipods, do show that it had a pair of roll stabilizers, which help to prevent parametric rolling from getting out of hand, as on the Pacific Sun. Here's what the Sperry's brand of stabilizer looks like:

 Here's the port stabilizer - it's the red rectangle jutting out:

 Here's a closeup of the stabilizer:

It pivots into the hull to avoid damage during tug movements or docking - that's the purpose of the notch. 

The ship's roll stabilizer is visible from space (photo by DigitalGlobe, from the QuickBird satellite). It's the tiny white object on the ship's port side, about two-thirds the way down the length of the hull, measured from the stern, which is at the top of the image.

I find it interesting that the stabilizer is apparently undamaged, despite the scraping of the hull abaft that position. Such damage to the aft hull on the port side suggests to me that the ship was making a hard turn to starboard at the time it struck the rocks. 

With a stern drive like the Concordia had, a hard turn to starboard (right) shoves the stern to port (the left), which forces the stern against obstacles lying on that side. It might explain why the roll stabilizer appears to be undamaged, even though it juts well away from the hull. Another possibility is that the roll stabilizers were stowed at the time of first impact and popped out later. The VDR data should settle that. In any case it seems likely that the helm was hard over at the time of impact.

Costa Concordia: Investigative tools

Sit-rep on the Costa Concordia: six bodies have been found; sixteen people who were on board have not reported to authorities; the ship may come off the rocks at any time and slide into deep water; and the owners have issued a statement about possible human error that distances them from the captain. An Italian helicopter pulled off an employee yesterday (photo in the Telegraph, from AFP):

Here's the flotilla of used lifeboats, from Wiki Commons:

Because of the rapid heeling of the ship in the final moments, many passengers had to climb down ropes or jump.

In my previous post I mentioned the black box required on newbuild passenger ships like the Costa Concordia after 2002, the voyage data recorder, aka marine event recorder. Here's a photo of such a rig from Transas:

Here's a brochure for one brand, a Raytheon model, of VDR. For a ship of the Costa Concordia's class, a VDR captures the following:

• Position, date, time using GPS.
• Speed log – Speed through water or speed over ground.
• Gyro compass – Heading.
• Radar – As displayed or AIS data if no off-the-shelf converter available for the Radar video.
• Audio from the bridge, including bridge wings.
• VHF radio communications.
• Echo sounder – Depth under keel.
• Hull openings – Status of hull doors as indicated on the bridge.
• Watertight & fire doors status as indicated on the bridge.
• Hull stress – Accelerations and hull stresses.
• Rudder (or Azipod) angle– Order and feedback response.
• Engine/Propeller – Order and feedback response.
• Thrusters – Status, direction, amount of thrust percentage or RPM.
• Anemometer and weather vane – Wind speed and direction
• Main alarms – All alarms mandated by the International Maritime Organization

One channel of main-alarm data that interests me is a time plot of degrees from vertical. When did the ship start to heel over? Late-model cruise ships with a shallow draft and a high stack of hotel-like cabins have a metacentric height that can make them tippy under certain conditions. Here's a Globalspec link to how metacentric height is calculated:

Some conditions that can lead to a capsize are improper loading or a tight turn, particularly if these combine with a stiff wind. Here's a link to the following detailed graphic from the Daily Mail, showing such a U-turn before the ship rolled onto its side:

Note the bow-on profile of the ship on the right of the graphic, comparing how much structure was above the waterline compared to how much below.

While blogging about containerships in distress (such as Rena, another ship that hit the rocks) I promised a post about parametric rolling, in which a ship's physical features interact with heavy seas of a specific wavelength. The result is a harmonic that can dangerously magnify a ship's tendency to roll, particularly when the ship is almost bow-on to the waves. (Traditionally, shipmasters head directly into the waves during a storm, because that was thought to be the safest course.)

While parametric rolling wasn't a factor in the Costa Concordia's loss, I mention it because it's a remarkable phenomenon of the open sea and was unrecognized until the modern era. It's already damaged some containerships, and may have imperiled the cruise ship Pacific Sun during a South Pacific storm in 2008. Dozens of passengers were injured, many by furnishings on the move. Still, Pacific Sun made it back to shore from its "Summer Daydream" cruise, which is pretty amazing since video taken from a helicopter shows rolling so extreme (31 degrees off vertical) that the underside of her hull is visible. Here's an image from the British investigative report, tilted to indicate to readers what the roll felt like from inside:

Wreck of the Costa Concordia: Update

Watching early reports about the allision of the cruise liner Costa Concordia on a reef, followed by capsizing. This Getty image:

Three are reported dead, and four dozen missing, but it's extremely difficult to keep track of 4,000-plus people when a ship sinks close to shore, so we can hope some of the missing crew and passengers are safe but unreported. 

The ship struck after 10 pm Friday evening. Here's an Associated Press photo of the hull the next day.

While it looks like two photographs stitched together, the brown section between the ocean and the white upper hull is the wrecked lower hull. That's some serious damage! And a big rock too.

It may be hard to believe that a ship traveling weekly on the same Mediterranean cruise route would smash into rocks after so many trips, it's more believable if the ship suffered some kind of power failure shortly before grounding. Modern computerized ships, particularly those relying on thruster pods like the Costa Concordia, are vulnerable to catastrophic power failures. While redundant generators and buses should prevent this, sometimes it happens.

Some reports point to a possible flaw in the navigational charts (a mischarted reef, or an unknown one), but I'd doubt that here. Here are graphics and charts on the Concordia's last voyage, from gCaptain. Fishermen and others who knew the waters said that the ship was off its usual route. 

The ship should have a record of events stored on its VDR (voyage data recorder), so the cause of the sinking won't remain a mystery for long. My particular interest is gathering lessons about time-critical, high-stress evacuation, so that's the aspect I'm watching as information emerges about how passengers crawled and climbed off the listing ship and found their way into the lifeboats.

After the Storm: Rena's Breakup

As predicted by salvage experts, the weekend storm broke the containership Rena in two, leaving the bow section on the reef:

Two days on, the bottom had fallen out of one section, along with the containers, leaving this strange skeleton of hatchway openings and hull:

To recap: On October 5 Rena crashed full speed onto Astrolabe Reef 14 miles outside the harbor at Tauranga, NZ. Remarkably, it held together for months, even though half the 47,000-ton ship was free to rise and fall with the waves, putting enormous stress on the midships section between the floating part and the grounded part. A crack in the hull developed early, and widened:

The numbers at the point of breakup:

• Containers lifted off by salvors and taken to shore: 389
• Containers that fell off before the storm: about 100
• Containers still on board at the time of the breakup: about 900
• Oil pumped out by salvage crews: 1,000 tons
• Oil still on board last weekend: about 400 tons, some of which is now headed out to sea:

There's no report out yet on why the ship went full speed onto rocks that are well known to mariners.

Deadly Elevator Accident: Interlocks under suspicion

Thoughts on information that's been released about the circumstances of Suzanne Hart's death December 14 in an elevator at the Young & Rubicam office building, 285 Madison Avenue, NYC. Here's a photo of the building entrance from NY Daily News, with an NYPD Emergency Service Unit heavy-rescue truck parked outside:

The office building opened in 1926. The accident happened in an elevator in the lower-floor bank, covering floors 1-12. The elevator is a traction device, which rolls along steel tracks while suspended from a steel cable or belt. The prime mover is an electric winch with electronic controls. 

Being licensed by NYC's Department of Buildings, and inspected by contractors, it's supposed to have multiple safety devices that prevent doors closing on people, and to prevent the car from moving without proper command.

December 13: A company called Transel Elevator comes to the building to perform routine work on the elevator. Here's a link to a Transel site. Transel advertises its reliance on non-proprietary control systems for construction and repairs.

December 14: Transel puts the car at 285 Madison Ave. back into service in the morning. It's unclear how much time passes, but at about 10 am the elevator car is on the ground floor, with two passengers inside, its doors open. As Hart begins to step in, a passenger presses the button for an upper floor. The car shoots upward when Hart is halfway in and pins her at the second floor, between the top of the hoistway opening and the floor of the car. The other two passengers in the car are trapped in this horrifying space for over an hour, until emergency workers get enough control of the machinery to extricate them. One has sued for emotional distress. 

There are reports that the impact was so violent the other elevators in the bank had to be checked for damage.

I looked through accounts of other mishaps involving uncommanded elevator movements, and what turned up. Here's a list of factors that investigators (including a firm hired by the Department of Buildings, and consultants hired by the parties) are likely to check.

Timing of events: After the elevator went back into service that morning, were any trouble reports posted before the fatality?

Electronic controls:  These include control panels up in the machinery room, near the hoist motor. Were jumper wires still in place from the repairs? Jumpers -- temporary wires with alligator clips at each end -- are a possible cause when electronics go crazy soon after repair work on it. It's not necessarily a problem to use jumpers for diagnosis while the car is out of service, but the machine must not be restored to service with jumpers still in place; they could short-circuit the interlocks that keep passengers safe.

Counterweights: Were these in proper balance, such that the car had no strong tendency to lurch upward when lightly loaded?

Overspeed governor: Probably not relevant here given the very short distance of travel, but these devices clamp the car to the rails when velocity exceeds a set value, commonly 125% of the maximum speed. They're standard on traction systems to guard against excessive downward speeds, in case of cable break. Some models protect against upward movement.

Doorway detectors and associated interlocks: Depending on the model, these can include photoelectric light beams, safety edges on the doors (the gadgets that look like retracting bumpers at the door edges), and infrared curtains. Any of these should have detected that Hart was in the doorway, which with safety interlocks should have kept the doors from closing. And with the car doors and hoistway doors standing open, the elevator shouldn't have moved at all. 

Thus the recent speculation about some kind of serious problem remaining in the electronics at 10 am.

Weaubleau's Round Rocks

Driving back to Minnesota with the family after Thanksgiving, Passenger attempted to amuse Driver with area factoids from Wiki and its links. We were on Highway 13 approaching Osceola, MO, which is north-northeast of Weaubleau. So that prompted a search for information on the enigmatic Weaubleau Eggs, aka “round rocks.”

Google offers this photo:

Thousands have been found in the vicinity, but they're rare elsewhere on Earth. The most common sizes run from golf-balls to grapefruit. Over the years, residents of Weaubleau and Osceola built stairways and walls from them.

Most are round or ovoid, a little flattened on one side. Cracking them open reveals that the bulk of each egg is chert, a hard, glossy sedimentary rock that results when silica replaces portions of calcium-carbonate limestone. Flint is one type of chert.

Weaubleau eggs often have a small piece of gray or greenish mudstone at the center, hence comparisons to eggs and their yolks. Sometimes the mudstone may hold the fossil of a conodont, a tiny, toothy eel. 

Round rocks sometimes occur together in ancient gravel deposits. This geology paper on the Weaubleau crater calls them shale-filled paleokarst pockets. Here's a photo from that paper:

The current consensus among the rock-minded is that the round rocks originated with a meteorite impact circa 320-340 million years ago. Given that there are three non-concentric rings visible with synthetic-aperture radar, the cause may have been two or three serial impacts in close proximity. At any rate, something produced rings of shocked rock, the largest of which is about 12 miles in diameter.

Weaubleau counts as one of the Top 50 biggest meteor impacts detected on Earth, and offers more visible remnants than the average site. 

There's another possible distinction, even rarer if confirmed. Weaubleau could be one of a near-linear string of craters along the 38th Parallel:

If these are not coincidental, the Weaubleau event would be part of the only known serial-meteorite-impact on Earth.

But this caveat: Planetary geologists say a serial impact on Earth is improbable. Given the Earth's relatively weak gravity well, compared to that of Jupiter, terrestial gravity is supposed to be too weak to break up even poorly cemented comets. So before agreeing, they'd want more proof that the 38^th Parallel craters are of the same age. 

But the Moon appears to have several crater strings from serial impacts, so it's not impossible.

Back to rock hunting. The best place to find a specimen is near the rim of the crater. North of Osceola, we turned off the main highway and found this estimable egg in a ditch:

It's a little more than seven inches in diameter, and weighs 13 pounds, so it's on the upper end of egg size. And no, we don't plan on breaking it open to see if there's a baby conodont fossil inside.

What would form such odd objects, and in such great numbers? One TV news account surmised that the eggs were formed immediately by the impact and flew like so many cannonballs from ground zero. More likely is that the impact threw out little pieces of mudstone from the crater that, in time, prompted chert formation. The phrase doesn't roll off the tongue like the term "cannonball," but rockhounds say that Weaubleau eggs are spherical nodules of chert that nucleated around siltstone clasts.

Rena's Box Score: Storms set the pace

There are hints that a newly invigorated container removal effort at the MV Rena, still grounded off New Zealand, may not have much longer to operate. 

Rena's hull is seriously cracked and likely to finish breaking in two if the weather gets bad enough. It's amazing to me that it's still in one piece at all, given that the bow has been on the rocks for more than two months while the stern remains afloat, defying tides and ocean swells.

And storms. A 30-knot storm, with 13-foot waves, is forecast for the weekend. It'll be rough if anybody's working inside:

The crane-carrying barge Sea Tow 60 has stopped trying to lift containers, moving aside for the heavy lifter Smit Borneo. Here's a picture of Borneo on its way to the port of Tauranga, NZ, taking waves in stride:

Borneo has since arrived at Rena's location. It was lifting six containers at a time with the pedestal mounted 500-ton boom, but heavy weather and then a mechanical issue suspended the crane work. Here's containerized cargo arriving on shore:

Here's the current box score ... Out of 1,368 containers on board when the ship hit Astrolabe reef:

• Still on board, mostly below deck: 1,072
• Fell off and whereabouts unknown: 65
• Fell off, but rounded up: 25
• Removed by crane: 206

Containers are still breaking away. I'll post another note after the storm passes.