Friday, September 5, 2014

Canada CHS update in the Marine GeoGarage

As our public viewer is not yet available
(currently under construction, upgrading to Google Maps API v3 as v2 is officially no more supported),
this info is primarily intended to our B2B customers which use our nautical charts layers
in their own webmapping applications through our GeoGarage API

CHS raster charts coverage

40 charts have been updated (August 28, 2014)
    • 1311 SOREL-TRACY À / TO VARENNES
    • 1312 LAC SAINT-PIERRE
    • 1313 BATISCAN AU/TO LAC SAINT-PIERRE
    • 1314 DONNACONA À/TO BATISCAN
    • 3050A KOOTENAY RIVER MILE 0 TO MILE 8.7
    • 3050B SHEET 2 KOOTENAY RIVER MILE 8.3 TO MILE 16.5
    • 3050C KOOTENAY RIVER MILE 15.8 TO 24.9
    • 3050D KOOTENAY RIVER MILE 24.2 TO 29
    • 3050E SHEET 5 KOOTENAY LAKE KUSKONOOK TO BOSWELL
    • 3050F KOOTENAY LAKE RHINOCEROS POINT TO RIONDEL
    • 3050G KOOTENAY LAKE RIONDEL TO KASLO
    • 3050H KOOTENAY LAKE KASLO TO LARDEAU
    • 3050I WEST ARM KOOTENAY LAKE PROCTOR LIGHT TO HARROP NARROWS
    • 3050J WEST ARM KOOTENAY LAKE HARROP NARROWS TO NINE MILE NARROWS
    • 3050K WEST ARM KOOTENAY LAKE NINE MILE NARROWS TO FIVE MILE POINT
    • 3050L WEST ARM KOOTENAY LAKE FIVE MILE POINT TO NELSON
    • 3050M WEST ARM KOOTENAY LAKE NELSON TO TAGHUM
    • 3050N KOOTENAY RIVER TAGHUM TO CORRA LINN DAM
    • 3442 NORTH PENDER ISLAND TO/À THETIS ISLAND
    • 3456 HALIBUT BANK TO/À BALLENAS CHANNEL
    • 3459 APPROACHES TO/APPROCHES À NANOOSE HARBOUR
    • 3475 PLANS - STUART CHANNEL
    • 3490 FRASER RIVER/FLEUVE FRASER - SAND HEADS TO/À DOUGLAS ISLANDS BC
    • 3491 FRASER RIVER/FLEUVE FRASER - NORTH ARM AB
    • 3512 STRAIT OF GEORGIA CENTRAL PORTION/PARTIE CENTRALE
    • 3675 NOOTKA SOUND
    • 3676 ESPERANZA INLET
    • 3726 LAREDO SOUND AND APPROACHES
    • 3737 LAREDO CHANNEL - INCLUDING / Y COMPRIS LAREDO INLET AND / ET SURF INLET
    • 3744 QUEEN CHARLOTTE SOUND
    • 3902 HECATE STRAIT
    • 3936 FITZ HUGH SOUND TO / À LAMA PASSAGE
    • 3985 PRINCIPE CHANNEL - CENTRAL PORTION/PARTIE CENTRALE AND/ET PETREL CHANNEL
    • 4026 HAVRE-SAINT-PIERRE ET/AND CAP DES ROSIERS À/TO POINTE DES MONTS
    • 4114 CAMPOBELLO ISLAND
    • 4115 PASSAMAQUODDY BAY AND / ET ST CROIX RIVER
    • 4118 ST. MARY'S BAY
    • 4237 APPROACHES TO / APPROCHES DE HALIFAX HARBOUR
    • 4266 SYDNEY HARBOUR
    • 4277 GREAT BRAS D'OR / ST. ANDREWS AND / ET ST. ANNS BAY
    • 4335 STRAIT OF CANSO AND APPROACHES/ET LES APPROCHES
    • 4367 FLINT ISLAND TO/À CAPE SMOKEY
    • 4385 CHEBUCTO HEAD TO/À BETTY ISLAND
    • 4466 HILLSBOROUGH BAY
    • 4825 BURGEO AND/ET RAMEA ISLANDS
    • 4846 MOTION BAY TO/À CAPE ST FRANCIS
    • 4847 CONCEPTION BAY
    • 4848 LONG POND
    • 4857 INDIAN BAY TO/À WADHAM ISLANDS
    • 4911 ENTRÉE À/ENTRANCE TO MIRAMICHI RIVER
    • 4913 CARAQUET HARBOUR BAIE DE SHIPPEGAN ET/AND MISCOU HARBOUR
    • 6207 SLAVE LAKE TO/À EAGLENEST LAKE
    • 7750 APPROACHES TO/APPROCHES À CAMBRIDGE BAY
      So 693 charts (1677 including sub-charts) are available in the Canada CHS layer. (see coverage)

      Note : don't forget to visit 'Notices to Mariners' published monthly and available from the Canadian Coast Guard both online or through a free hardcopy subscription service.
      This essential publication provides the latest information on changes to the aids to navigation system, as well as updates from CHS regarding CHS charts and publications.
      See also written Notices to Shipping and Navarea warnings : NOTSHIP

      The science of tides

       
       Watching the Tides
      Ocean tides rise and fall twice a day, influenced by the gravitational forces of the sun and moon.
      Studying tides' rhythmic movements helps us understand both the ocean and the cosmos.
      Astronomer Ben Burress explains how tides work, and visiting Crissy Field in San Francisco to see the oldest continually operating tidal gauge in the Western Hemisphere. 


      Tides are the most consistent variables in our surfing lives.
      The Ocean is always either receding or approaching your shoreline.
      It is a constant reminder of the geometry and power of astronomical forces.
      Tides erode coastlines, impact marine ecosystems and even facilitated early life leaving the sea.
      Rising tides can pull swell onto a beach while dropping tides can focus wave energy to a shallow sandbar or reef.
      Tides are caused by the gravitational dance between the Earth, Moon and Sun.


      Gravity is a fundamental force that attracts every object to every other object.
      It’s the force that brought Newton’s apple to the ground and the force that accelerates a bodysurfer down a wave face.
      The more massive the object, the stronger it’s gravitational pull.
      The closer two objects are, the stronger the pull of gravity between them.
      This pull between objects is called a tidal force.

      The action of the tides, the variation in sea levels due to the gravitational pull of the Moon and Sun on the Earth.

      The Moon, Earth and Sun are freaking huge.
      About 36 Moons can fit inside the Earth and 1.3 million Earths fit in the Sun.
      Although much much less massive than the Sun, the Moon’s gravitation has a stronger impact on Earth because it is much closer.
      The sun is 93 million miles away from the Earth while the Moon is only 240,000.
      Much like an apple is pulled to the ground, the Ocean is pulled toward the Moon.
      Luna’s tidal force tugs on the Earth, pulling the Ocean off some beaches for low tide and onto others for high tide.
      The force also impacts the Earth’s crust and atmosphere but only fractionally compared to liquid water.

       source : NOAA

      Tides are caused by two bulges formed in the Ocean.
      One from the tidal force toward the Moon and the other on the opposite side of the Earth caused by inertia as our planet spins.
      This is the same centrifugal force that keeps the water in the bucket when you swing it  over your head.
      The bulges follow the Moon and the spinning Earth around the globe.
      When a bulge passes your beach, the tide rises.

      The monthly tide calendar parallels the monthly lunar phase calendar.
      New Moon is the alignment of Sun, Moon, Earth.
      We do not see the Moon because all the light is bouncing off the Far Side.
      This formation of three bodies in a line is called syzygy and it amplifies the tidal forces on the bodies. During New and Full Moons, the alignment of the Earth, Moon and Sun creates greater tidal range. Higher highs, lower lows and more dramatic swings; this is called the spring tide.
      Not named for the season, but because it “springs forth.”

       Lunar phases (L) and notice the strong spring tides near Full and New Moon (R).

      As the Moon orbits the Earth, it “waxes,” growing and showing more of her face each day.
      After about 14 days the alignment is Sun, Earth, Moon, with the full face of Luna reflecting light. Then Luna wanes- shrinking each day until New Moon again two weeks later. 
      The rest of the tide chart flows up and down between these points with the first and third quarter Moons having the smallest tidal range.
      These are neap tides.

      The differences between tides from day to day and month to month is the result of astronomical motions.
      Luna’s orbit around the Earth forms an oval or ellipse.
      Sometimes she is closer to Earth than other times.
      King tides are the highest tides of the year and exist when the Moon is closest to the Earth and in syzygy alignment with the Sun.


      Ebb is the decreasing tide while flood tide is the increasing.
      The moment the tide changes is called slack water. 
      There is 6 hours between each high and low.
      Tomorrow’s high tide will be about an hour later than today’s.
      Tides vary greatly all across the globe depending on factors like geographic location, local weather/swell and shoreline geology.
      The East Coast of the US is semi-diurnal.
      This refers to two highs and two lows each day of roughly the same height.
      The West Coast is mixed semidiurnal: two highs and two lows each day with different heights.
      The Gulf of Mexico is diurnal: one high and one low each day.


      Three billion years ago, the Moon was much closer to the Earth, the tides rose thousands of feet over the land and then back to sea.
      Today, the greatest tidal range exists in the Bay of Fundy, Nova Scotia.
      Tides are focused in and out of the bay resulting in a 50ft.+ tidal change.
      The lowest tidal ranges of just a foot occur in the Mediterranean, Baltic and Caribbean Seas.
      The middle of Ocean basins also experience minimal tidal changes.
      Hawaii’s tides rarely change more than 2ft.
      However, California’s tides exhibit much more dynamism. 
      California king tides can approach 8ft. with an accompanying -2ft. low.

       Bay of Fundy of Nova Scotia: largest tidal range on Earth.
      (see Tides.gc.ca for Hopewell Cape)

      Tides impact waves in a variety of ways.
      Surf spots that prefer certain tides are referred to as tide dependent. 
      Some spots are flat until a tidal push focuses the energy on the beach.
      Other spots stop breaking when the tide floods because the water becomes too deep for the waves to shoal.
      As a general rule, incoming, low to high tide is preferable for many surf spots.
      Low tide can create fast, hollow, plunging waves. High tide often produces slow, mushy, spilling waves.
      However, many shorebreak womps prefer high tides pushing up the beach.
      Changing tides can also alter the strength and direction of longshore and rip currents.

      Death, taxes and tides.
      The great English poet, Geoffrey Chaucer, wrote “Time and tide wait for no man.”
      They are predictable and unstoppable.
      Tides are the only variable in surf forecasting that are concrete and certain. 
      Waveriders can feel the rhythm of the tides.
      We experience the astronomical forces on a different level than the mathematicians and physicists.

       High tide pushing up the beach.

      Links :



      Thursday, September 4, 2014

      Nature’s tiny engineers : how corals stir up their world for nutrients

       Scientists have found that corals, long believed to be passive organisms relying entirely on ocean currents to deliver nutrients, are actually quite active, engineering their environment producing strong swirls of water that draw nutrients toward the coral, while driving potentially toxic waste products away.

      From BBC by Victoria Gill

      Coral reefs may look static to the naked eye, but scientists have now seen "violent" activity on their surface.

      Using powerful microscopes, researchers filmed tiny hairs on the surface of corals "stirring up" surrounding water.
      They say that these swirls of water draw nutrients towards the coral, and may also drive away potentially toxic waste products.
      The findings are published in Proceedings of the National Academy of Sciences.
      Scientists from the Massachusetts Institute of Technology and the Weizmann Institute of Science (WIS) in Israel studied corals grown in a laboratory tank.

      "The general thinking has been that corals are completely dependent upon ambient flow from tides and turbulence [to supply nutrients]," said Orr Shapiro from WIS.
      These detailed observations overturn that idea.


      Tracer particles in the water enable researchers to produce images of the flow

      'Vigorous stirring'

      The researchers added tiny "tracer particles" to the water, which enabled them to see and capture images of the movement and flow near the surface of the coral.
      They also combined powerful microscopes with high speed cameras, capturing footage of the tiny hairs, or cilia, on the corals' surface.
      The resulting slow-motion footage was magnified by up to 1,000 times.
      It showed, the researchers reported, the cilia beating and "vigorously stirring a layer of water that extended up to 2mm from the coral surface".

      "I was very surprised and so was the entire team," another author of the study, Prof Roman Stocker from MIT told BBC News.
      "We knew that corals have cilia, but did not expect that they could produce flows that are so violent."

      Such a close-up understanding of how coral reefs work could help predict how they will cope with a changing ocean environment in the face of climate change.
      "An active control over the environment suggests a potential ability to cope with changing conditions," said Prof Stocker.
      "Although we must be careful in drawing this conclusion, as other factors, such as increased virulence of bacterial pathogens [in warmer] conditions may well tip the balance for corals the other way."

      The researcher also pointed out that the experiments could play a role in human health research.
      Cilia are found inside human airways, where they help to sweep away contaminants, but these microscopic internal hairs are very difficult to study.

      "It's rare that you have a situation in which you see cilia on the outside of an animal," said Prof Stocker. "
      "So corals could provide a general model for understanding ciliary processes related to disease."

      Wednesday, September 3, 2014

      Coop’s Citizen Sci Scoop: fishermen, sailor, beachcomber, diver – the seas of research helpers

      Commander Matthew Fontaine Maury USN painting

      From Plos by Caren Cooper

      Many of you have had summer fun with citizen science at the beach, intertidal zone, and ocean.
      What do your efforts contribute to?
      In a new chapter, Martin Thiel and colleagues tallied the contributions of citizen science to marine research.
      Thiel is known for his research relying on volunteers who clean up beaches, but for this chapter they looked at over 200 studies on topics that ranged from algae to vertebrates.
      About 40 of the studies were local, 122 were regional, and 65 involved larger geographic regions (28 national, 28 international, 9 global).
      Most commonly projects involved surveys, transects, and opportunistic sightings.
      Marine scientists often depend on non-scientists, from general public to fishermen to ship crews to beachgoers.
      Thiel reviewed papers published within the past 30 years, but some of the research papers were based on decades of citizen science; one was based on over 150 years of continuous data collection.

      This is not a new phenomenon. I first learned about the history of citizen science when I read about the father of Oceanography, Matthew Maury.
      In this context, I felt that modern citizen science is actually quite retro, which inspired my post about Maury (below), originally at Scientific American.

      My area of research, citizen science—a term applied to data collection methods that engage the public in scientific research—is not a newly invented style, either.
      It’s rather retro fashion.
      Public involvement in science is a time-honored tradition that is enjoying a hip resurgence as it combines with today’s sophisticated and increasingly commonplace technologies, like GPS units and smart phones.

      In an earlier Guest Blog post I suggested that citizen science in the US dated as far back as 1776, with Thomas Jefferson’s vision of a nationwide weather monitoring program.
      Afterward, people wrote in to tell me about their own favorites.
      Though many of these, such as Henry David Thoreau or Charles Darwin, were naturalists or lay scientists rather than citizen scientists per se, two suggestions particularly intrigued me: Mathew Fontaine Maury, an American naval officer, and William Whewell, a British scholar.

      Both men spearheaded citizen science in the mid-1800s with large-scale, accurate and systematic science projects.
      The projects were carried out by rank amateurs, and led to discoveries that had great societal importance.
      The two men differed in their nationality, vocation, and perspective on the role of science in society. Their stories illustrate that we are in an exciting era where history is indeed repeating itself.


       Matthew Fontaine Maury Statue

      For today, let’s meet the American.
      In 1825, Matthew Fontaine Maury was a 19-year-old when he left home and joined the U.S. Navy. Maury began his naval service as a midshipman on a frigate (the Brandywine), rose through the ranks of lieutenant, commander, and commodore, and culminated his career as Superintendent of the U.S. Naval Observatory.
      Over the course of his distinguished naval career, Maury contributed to our understanding of astronomy, oceanography, and meteorology.
      He carried out much of his research by crowdsourcing dispersed and historical observational records and through the establishment of a global citizen science project that continues to this day.

      Matthew Fontaine Maury is the father of modern hydrography in the United States Navy.
      He served as superintendent of the U.S. Naval Observatory from its founding to the start of the Civil War, when he resign to supervise maritime defenses for the Confederacy.
      This chart pays tribute to his leading role in establishing the charting and scientific studies that were critical to the ascendancy of the United States as a maritime economic and military power in the nineteenth century.

      From the start, Maury showed an interest in engaging the public in exploring the world.
      Soon after returning from his first voyage, he became the first U.S. Naval officer to write a book on nautical science, which was later used by the Naval Academy.
      Edgar Allan Poe was impressed by it, writing,

      “This volume, from an officer of our Navy, and a Virginian, strong commends itself to notice…The spirit of literary improvement has been awakened among the officers of our gallant Navy. We are pleased to see that science is gaining voteries from its ranks.”

      Maury’s later writings are lyrical praises of the cosmos that can make Carl Sagan’s writings appear retro. In 1849, Maury presented to the Virginia Historical Society about his work at the National Observatory, writing:

      “At the dead hour of the night, when the world is hushed in sleep and all is still; when there is not a sound to be heard save the dead beat escapement of the clock, counting with hollow voice the footsteps of time in ceaseless round, I turn to the Ephemeris and find there, by calculations made years ago, that when that clock tells a certain hour, a star which I never saw will be in the field of the telescope for a moment, flit through and then disappear. The instrument is set; the moment approaches and is intently awaited—I look—the star mute with eloquence that gathers sublimity from the silence of the night, comes smiling and dancing into the field, and at the instant predicted even to the fraction of a second, it makes its transit and is gone. With emotions too deep for the organs of speech, the heart swells out with unutterable anthems; we then see that there is harmony in the heavens above; and though we cannot hear, we feel the ‘music of the spheres.’”

        Andriveau-Goujon / Matthew Fontaine Maury:  Courants De L'Atmosphere 
      d'Apres Le Lt. F. Maury (source : raremaps.com)

      Maury embarked in crowdsourcing data in 1842 when, as a lieutenant, he was placed in charge of the Depot of Charts and Instruments of the Navy Department.
      Sailors followed a strict routine and were systematic in recording very specific observations around the clock. Ships were mobile weather stations, accumulating a standardized set of weather variables with the strictest regularity at 15 minute intervals.
      As much as sailors emphasized these routines, once a voyage was completed, the logs were practically viewed as rubbish.

      But when Maury saw the Navy’s stockpile of old ships logs, he quickly realized the collective information could improve navigation.
      Maury developed a method to systematically extract key information from each log book.
      Today, in an era of climate change, the information from old logs are valuable again.
      For this reason, people across the globe transcribe old ship logs in a project called Old Weather, one of several on-line citizen science projects in Zooniverse.
      Maury didn’t have the help of an online network of volunteers, but he still assembled the resulting information into the colorful publication of a “Wind and Current Chart” of the North Atlantic in 1847.

       [Matthew F. Maury. Whale Chart. Washington, D.C.: Naval Observatory, 1851. Color lithograph. Geography and Map Division, G9096s. C7 var. M3, series F (8). Source: Library of Congress.]

      It was a natural progression for Maury to develop a system that streamlined his ability to continually improve navigational charts.
      Maury developed standardized data forms that could function as specially formatted logs.
      He sent these forms, along with instructions and up-to-date charts, to mariners.
      Some data may have come from Navy ships, but the notable data were voluntary contributions from merchant vessels.
      Within four years, over one thousand ships were sending reports to Maury from across the seven seas!
      Maury quickly incorporated the data to make new charts of trade winds, thermal charts, whale charts, and more.
      The increased speed of travel across all the oceans saved millions for ocean commerce.
      Before Maury’s charts, passage from New York to San Francisco took over a year.
      With the help of Maury’s full color charts, the trip could be taken in a swifter vessel and reduced to a speedy three months.

      Overview of Sailing Directions coverage.
      The numbers in the squares indicate the individual Planning Guide coverage areas.

      Maury’s legacy continued to contemporary times in the form of Sailing Directions, a 42-volume publication by the National Geospatial-Intelligence Agency (NGA).
      Maury’s brainchild ended up in the NGA, the same organization credited with gathering the intelligence that allowed the U.S. military to raid the hiding place in Pakistan of Osama Bin Laden in 2011.
      Yet, because Sailing Directions is based on data contributed by cooperating merchant ships, I categorize it as citizen science.

       Maury's Wind & Current Chart . . . (Atlantic Ocean & Coast of West Africa)
      source : raremaps.com

      In the late 1840s, Maury urged farmers to start a similar global system of meteorological observations on land, using the telegraph to aggregate reports in one location where his office could formulate weather forecasts.
      When Thomas Jefferson envisioned this, the Revolutionary War made it difficult if not impossible. For Maury, the Civil War had the same effect.

      Yet Maury continued to see uses for large piles of otherwise overlooked observations.
      In 1847, Maury saw a way to use historic observations to aid astronomy.
      That year, European astronomers discovered Neptune.
      This was the first time a planet had been found through mathematics: perturbations in the orbit of Uranus could not be mathematically resolved unless another large object beyond it was assumed to exert influence on its orbit.
      The key element of a planetary discovery is the computation of its orbit, but for Neptune, the mathematical rather than strictly visual nature of the discovery meant that computation would take 50 years or more.
      Maury realized that instead of waiting 50 years, he could search archived records for clues in the past 50 years.
      He and an assistant found that Neptune had been seen in 1795 but misidentified as a fixed star, and this enabled immediate computation of Neptune’s orbit.

      When Matthew Maury saw a problem, he used scientific observations to find a solution.
      Maury’s ability to express his curiosity and delight with the natural world inspired others to join his scientific pursuits and gave them a more reliable way of understanding the world.
      Sailors’ lives were full of risks because they didn’t fully understand the oceans.
      To deal with the risk, they believed in omens, superstitions, and good and bad luck.
      The maps Maury produced immediately dispelled some of the misunderstanding and allowed mariners to benefit from collective knowledge.

       Matthew Maury at the origin of the Marine GeoGarage baseline
      Marine GeoGarage, nautical charts web & mobile platform :
      "just the mapping apps for the 70% of the world that Google Maps does not cover..."

      see GeoGarage blog
       
      Today, the benefits of collective knowledge are helping turn citizen science into a retro fashion.
      It’s growing in popularity, independently in many disciplines, and emerging under different names (Community-based Participatory Science, Participatory Action Research, Open Science, Street Science, Community Science, Crowdsourcing, and the list goes on).
      An umbrella term, Public Participation in Scientific Research, now unites the field—and I’ve recently returned from a conference that brought together almost 300 people active in this field.

      No matter what it’s called, people participated in Maury’s science to make their lives better, and to feel enchanted and curious through the process of discovery.
      Maury could be a poster child for a time when citizen science embodied the democratization of science.
      Maury’s research was by the people, and for the people.
      During the same period as Maury’s work, another pioneer in citizen science was working to professionalize science and to distinguish the scientist from society.

      Links :

      Tuesday, September 2, 2014

      How the International Space Station and Automatic Identification System (AIS) saved a man lost at sea

      The Vessel-ID System investigation on the International Space Station demonstrated the ability for a space-based radio receiver to track a ship’s Automatic Identification System (AIS) signal, the marine equivalent of the air traffic control system.

      From Redorbit by Laura Niles

      The Vessel-ID System investigation on the space station demonstrated the ability for an orbit-based radio receiver to track a ship’s Automatic Identification System (AIS) signal.
      The AIS signal is the marine equivalent of the air traffic control system.
      The Norwegian User Support and Operation Centre in Trondheim, Norway, receives the data for near-continuous evaluation.
      The Vessel-ID System is installed on the European Space Agency’s Columbus module.

      Since being turned on in 2010, Vessel-ID has been able to relay more than 400,000 ship position reports from more than 22,000 ships in a single day, greatly advancing the ship tracking ability of coast guards around the world.
      This ability, coupled with multiple AIS tracking satellites launched since, is providing safer travel among the waves for thousands of ships around the globe.
      The ship identification and tracking system technology already aided in orienting rescue services for a lone survivor stranded in the North Sea, giving new hope to once impossible situations.

      “This brought a whole new dimension to the monitoring of ship traffic on the open oceans,” said Terje Wahl, of the Norwegian Space Centre.
      “This project demonstrates that the International Space Station is not just for science and astronauts, but it really benefits mankind with down-to-Earth applications.”

      AISSat-1 Real-time (RT) coverage area (1 year of data)

      FFI has performed a feasibility study on space-based reception of AIS messages.
      The results show a ship detection probability of near 100% for up to 1000 ships within the coverage area, and a signal power margin of 10 to 20 dB for a standard AIS receiver.
      A space-based AIS receiver will cover Norwegian waters up to 15 times a day in the northern region, and more than 8 times a day in the south.
      The data will include ship identity, position, speed, bearing, etc, and make it possible to track a high number of ships.
      A constellation of four satellites will give global coverage approximately every hour.
      To overcome saturation problems for more than 1000 ships, a study on an optimized system for global surveillance was done and presented to the International Maritime Organization.
      This slightly modified AIS system can be an option for Long- Range Identification and Tracking.

      Links :