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Binnacle

Our school is right by Boston Harbor – learning about the sea is second nature to many of our staff. So we love to tie maritime history and science into our curriculum.

Binnacle maritime

Photo by RK

As you enter our school, you pass by a binnacle – what was it used for?

A binnacle is a waist-high case, found on the deck of a ship, that holds the compass.

It is mounted in gimbals to keep it level while the ship pitched and rolled.

It also has a mechanism to compensate for errors in detecting the Earth’s magnetic field.

Every ship’s captain would use one, for navigating in and out of Boston Harbor, and around the world.

 

Here we see Boston Harbor – now let’s get in to how the binnacle works!

Boston Harbor Islands map

This map is from mass.gov/eea/images/dcr

 

Why did we need to develop the binnacle?

Excerpted from Magnetic Deviation: Comprehension, Compensation and Computation by Ron Doerfler  

Today, radio navigational systems such as LORAN and GPS, and inertial navigation systems with ring and fiber-optic gyros, gyrocompasses and the like have reduced the use of a ship’s compass to worst-case scenarios. But this triumph of mathematics and physics over the mysteries of magnetic deviation, entered into at a time when magnetic forces were barely understood and set against the backdrop of hundreds of shipwrecks and thousands of lost lives, is an enriching chapter in the history of science.

The Sources of Compass Error

Ron Doerfler writes:

Compasses on ships fail to point to true (geographic) north due to two factors:

Magnetic variation (or magnetic declination) – the angle between magnetic north and geographic north due to the local direction of the Earth’s magnetic field, and

Magnetic deviation – the angle between the compass needle and magnetic north due to the presence of iron within the ship itself.

The algebraic sum of the magnetic variation and the magnetic deviation is known as the compass error. It is a very important thing to know.

Magnetic Variation

Magnetic variation has been known from voyages since the early 1400s at least. Certainly Columbus was distressed as he crossed the Atlantic to find that magnetic north and true north (from celestial sightings) drifted significantly…

We now know that the locations of the Earth’s magnetic poles are not coincident with the geographic poles—not even close, really—and they are always wandering around.

magnetic north pole deviation

Image from commons.wikimedia.org, Magnetic_North_Pole_Positions. Red circles mark magnetic north pole positions as determined by direct observation, blue circles mark positions modelled using the GUFM model (1590–1980) and the IGRF model (1980–2010) in 2 year increments.

 

What’s the difference between where a compass needle points (magnetic north) and the geographic north pole? This is called the declination  It’s smallest near the equator, but generally gets large as one moves towards the poles.

On this map, the green arrows – the direction from the compass – point towards the magnetic north. The red arrows point towards the geographical north pole.

Notice how the left location (in Pacific ocean) shows the compass point a bit east of where we’d hope it would point; in the right location (in Atlantic Ocean) it shows the compass point a bit west of where we’d hope it points.

There’s also a special line where the magnetic north and geographic north point in the same direction.

Magnetic Declination

Image from Drillingformulas.com by Rachain J i

 

Here we can see how many degrees of deviation there are – the # of degrees between where the compass points, and where the north pole is. But – wait for it – the image is changing? The magnetic fields are significantly changing every year!

Estimated declination contours by year

from USGS.gov, faqs, what is declination

 

Magnetic Deviation

Ron Doerfler writes

There is an additional effect on the compass needle that took much longer to appreciate and even longer to understand. This magnetic deviation is due to the iron in a ship…

The first notice in print of this effect was by Joao de Castro of Portugal in 1538, in which he identified “the proximity of artillery pieces, anchors and other iron” as the source.

As better compass designs appeared, a difference in compass readings with their placement on the same ship became more apparent. Captains John Smith and James Cook warned about iron nails in the compass box or iron in steerage, and on Cook’s second circumnavigation William Wales found that changes in the ship’s course changed their measurements of magnetic variation by as much as 7°.

Here we see a modern naval vessel, with it’s own magnetic field. As a metal ship moves through Earth’s magnetic field, an electric current is produced within all that metal – and that current produces it’s own magnetic field. This field can affect the ship’s compass. That’s why a binnacle is designed to be adjustable, to compensate for this field. – RK

Degaussing magnetic field ship

image from slideplayer.com/slide/1632522/

 

Ron Doerfler writes

Captain Matthew Flinders (1774-1815) spent years in the very early 1800s on voyages to investigate these effects…. [he] eventually discovered that an iron bar placed vertically near the compass helped overcome the magnetic deviation. This Flinder’s bar is still used today in ships’ binnacles.

 

Apps & Interactives

NOAA Historical Magnetic Declination

Activities

Hands-on Activity: Nautical Navigation. Teachengineering.org

https://oceanservice.noaa.gov/education/lessons/plot_course.html

https://asa.com/certifications/asa-105-coastal-navigation/

 

Educational opportunities and museums

http://www.capecodmaritimemuseum.org/education/

https://timeandnavigation.si.edu/navigating-at-sea/longitude-problem/solving-longitude-problem/chronometer

http://abycinc.org/?page=standards

Important components

Quadrantal spheres (spherical quadrantal correctors)

Hood, over the compass bowl

flinders bar (vertical, soft iron corrector)

Learning Standards

Ocean Literacy Scope and Sequence for Grades K-12
6. The ocean and humans are inextricably interconnected: From the ocean we get foods, medicines, and mineral and energy resources. In addition, it provides jobs, supports our nation’s economy, serves as a highway for transportation of goods and people, and plays a role in national security.

Massachusetts 2016 Science and Technology/Engineering (STE) Standards
7.MS-PS2-5. Use scientific evidence to argue that fields exist between objects with mass, between magnetic objects, and between electrically charged objects that exert force on each other even though the objects are not in contact.

HS-PS2-1. Analyze data to support the claim that Newton’s second law of motion is a mathematical model describing change in motion (the acceleration) of objects when acted on by a net force….{forces can include magnetic forces}

HS-PS3-5. Develop and use a model of magnetic or electric fields to illustrate the forces and changes in energy between two magnetically or electrically charged objects changing relative position in a magnetic or electric field, respectively.

History standards

National Standards for History Basic Edition, 1996
5-12 Identify major technological developments in shipbuilding, navigation, and naval warfare and trace the cultural origins of various innovations.

Massachusetts History and Social Science Curriculum Framework
The Political, Intellectual and Economic Growth of the Colonies. Explain the importance of maritime commerce in the development of the economy of colonial Massachusetts, using historical societies and museums as needed.

National Curriculum Standards for Social Studies: A Framework for Teaching, Learning, and Assessment, National Council for the Social Studies, 2010.

 

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Model ship building in Boston

Topics: Scale conversions (math); Maritime history

Wooden ship models or wooden model ships are scale representations of ships, constructed mainly of wood. This type of model has been built for over two thousand years.

The ship: HMS Victory

She is a 104-gun first-rate ship of the line of the Royal Navy, ordered in 1758, laid down in 1759 and launched in 1765. She is best known for her role as Lord Nelson’s flagship at the Battle of Trafalgar on 21 October 1805. In 1922, she was moved to a dry dock at Portsmouth, England, and preserved as a museum ship. She has been the flagship of the First Sea Lord since October 2012 and is the world’s oldest naval ship still in commission.

The artist:

My father grew up on Boston Harbor. In addition to being a soldier, and an engineer with a research think tank, he did ship modeling at the USS Constitution Museum.

Dad's Kaiser HMS Victory model ship

In the USS Constitution Museum workshop, 1990’s.

Dad's Kaiser HMS Victory model ship II July 2004.JPG

A model of The US Navy Schooner Enterprise

The third ship to be named USS Enterprise was a schooner, built by Henry Spencer at Baltimore, Maryland, in 1799. It was overhauled and rebuilt several times, effectively changing from a twelve-gun schooner to a fourteen-gun topsail schooner and eventually to a brig.

Dad's Navy Schooner Enterprise model ship

Front view

Dad's Navy Schooner Enterprise II

The Flying Fish

Dad's Flying Fish ship model

The Flying Fish

Dad's Flying Fish ship model II

The last model ship hull that my father,ז״ל, was working on.

Dad's last model ship hull

 

Scale conversion factors

Written by George Kaiser (later incorporated into Wikipedia)

Instead of using plans made specifically for models, many model shipwrights use the actual blueprints for the original vessel. One can take drawings for the original ship to a blueprint service and have them blown up, or reduced to bring them to the new scale.

For instance, if the drawings are in 1/4″ scale and you intend to build in 3/16″, tell the service to reduce them 25%. You can use the conversion table below to determine the percentage of change. You can easily work directly from the original drawings however, by changing scale each time you make a measurement.

Table of Scale Conversion Factors

from to 1/8 to 3/16 to 1/4
1/16 2.0 3.0 4.0
1/12 1.5 2.25 3.0
3/32 1.33 2.0 2.67
1/8 1.0 1.5 2.0
5/32 0.8 1.2 1.6
3/16 0.67 1.0 1.33
1.5 0.625 0.94 1.25
7/32 0.57 0.86 1.14
1/4 0.5 0.75 1.0

The equation for converting a measurement in one scale to that of another scale is D2 = D1 x F where:

  • D1 = Dimension in the “from-scale”

  • D2 = Dimension in the “to-scale”

  • F = Conversion factor between scales

Example: A yardarm is 6″ long in 3/16″ scale. Find its length in 1/8″ scale.

  • F = .67 (from table)

  • D2 = 6″ X .67 = 4.02 = 4″

It is easier to make measurements in the metric system and then multiply them by the scale conversion factor. Scales are expressed in fractional inches, but fractions themselves are harder to work with than metric measurements.

For example, a hatch measures 1″ wide on the draft. You are building in 3/16″ scale. Measuring the hatch in metric, you measure 25 mm. The conversion factor for 1/4″ to 3/16′, according to the conversion table is .75. So 25 mm x .75 = 18.75 mm, or about 19 mm. That is the hatch size in 3/16″ scale.

Conversion is a fairly simple task once you start measuring in metric and converting according to the scale.

There is a simple conversion factor that allows you to determine the approximate size of a model by taking the actual measurements of the full-size ship and arriving at a scale factor. It is a rough way of deciding whether you want to build a model that is about two feet long, three feet long, or four feet long.

Here is a ship model conversion example using a real ship, the Hancock. This is a frigate appearing in Chappelle’s “History of American Sailing Ships”.

In this example we want to estimate its size as a model. We find that the length is given at 136 ft 7 in, which rounds off to 137 feet.

1/8 scale Feet divided by 8
3/16 scale Feet divided by 5.33
1/4 scale Feet divided by 4

To convert feet (of the actual ship) to the number of inches long that the model will be, use the factors in the table on the right.

To find the principal dimensions (length, height, and width) of a (square rigged) model in 1/8″ scale, then:

  1. Find scaled length by dividing 137 by 8 = 17.125″

  2. Find 50% of 17.125 and add it to 17.125 (8.56 + 17.125 = 25.685, about 25.5)

  3. Typically, the height of this model will be its length less 10% or about 23.1/2″

  4. Typically, the beam of this model will be its length divided by 4, or about 6 1/2″

Although this technique allows you to judge the approximate length of a proposed model from its true footage, only square riggers will fit the approximate height and beam by the above factors. To approximate these dimensions on other craft, scale the drawings from which you found the length and arrive at her mast heights and beam.

Reference: Williams, Guy R. The World of Model Ships and Boats London 1971 Page 30

External links

The USS Constitution Model Shipwright Guild

We are the largest model ship association on the East Coast and our friendly meetings overlooking Old Ironsides at the USS Constitution Museum are well attended. Novices and experienced model builders alike can have fun developing resources, experiences, and skills by joining us.

The USS Constitution Museum, located in the Charlestown Navy Yard, which is part of the Boston National Historical Park

The USS Constitution Museum serves as the memory and educational voice of USS Constitution, by collecting, preserving, and interpreting the stories of “Old Ironsides” and the people associated with her.

The science and history of the sea

https://en.wikipedia.org/wiki/Ship_model

https://en.wikipedia.org/wiki/Wooden_ship_model

Learning Standards

2016 Massachusetts Science and Technology/Engineering Curriculum Framework

Ocean Literacy The Essential Principles and Fundamental Concepts of Ocean Sciences: March 2013 and Ocean Literacy Network. The Centers for Ocean Sciences Education Excellence (COSEE) and Lawrence Hall of Science, University of California, Berkeley

Massachusetts History and Social Science Curriculum Frameworks

5.11 Explain the importance of maritime commerce in the development of the economy of colonial Massachusetts, using historical societies and museums as needed. (H, E)

5.32 Describe the causes of the war of 1812 and how events during the war contributed to a sense of American nationalism. A. British restrictions on trade and impressment.  B. Major battles and events of the war, including the role of the USS Constitution, the burning of the Capitol and the White House, and the Battle of New Orleans.

National Council for the Social Studies: National Curriculum Standards for Social Studies

Time, Continuity and Change: Through the study of the past and its legacy, learners examine the institutions, values, and beliefs of people in the past, acquire skills in historical inquiry and interpretation, and gain an understanding of how important historical events and developments have shaped the modern world. This theme appears in courses in history, as well as in other social studies courses for which knowledge of the past is important.

A study of the War of 1812 enables students to understand the roots of our modern nation. It was this time period and struggle that propelled us from a struggling young collection of states to a unified player on the world stage. Out of the conflict the nation gained a number of symbols including USS Constitution. The victories she brought home lifted the morale of the entire nation and endure in our nation’s memory today. – USS Constitution Museum, National Education Standards

Common Core ELA: Reading Instructional Texts

CCSS.ELA-LITERACY.RI.9-10.1
Cite strong and thorough textual evidence to support analysis of what the text says explicitly as well as inferences drawn from the text.

CCSS.ELA-LITERACY.RI.9-10.4
Determine the meaning of words and phrases as they are used in a text, including figurative, connotative, and technical meanings

Common Core ELA Writing

CCSS.ELA-LITERACY.W.9-10.1.C
Use words, phrases, and clauses to link the major sections of the text, create cohesion, and clarify the relationships between claim(s) and reasons, between reasons and evidence, and between claim(s) and counterclaims.

CCSS.ELA-LITERACY.W.9-10.1.D
Establish and maintain a formal style and objective tone while attending to the norms and conventions of the discipline in which they are writing.

CCSS.ELA-LITERACY.W.9-10.4
Produce clear and coherent writing in which the development, organization, and style are appropriate to task, purpose, and audience.

Teachable moments in Boston Harbor

The king tides are back, along with high winds, and they caused some havoc in Boston – leading to a teachable moment by Boston Harbor. A massive ship broke free from dock, and had drifted out – while crewed! They were rescued by tugboats, and the boat is now stationed between Nahant and Winthrop.

This was the perfect opportunity to discuss with students where Boston Harbor was, how tides are created, how to read maps, and maritime geography.

Seaport Boston harbor teaching

As for those King Tides:

It’s that time of the year again. Sure, the holiday season has returned, but so have — this week, at least — the king tides. The astronomically caused ultra-high tides peaked in Boston just before noon Tuesday, according to the National Oceanic and Atmospheric Administration. Reaching more than two feet higher than average daily high tides, the seasonal occurrence produced minor flooding in low-lying areas along the East Coast.

king tides NOAA Lunar orbit

Let’s see how the motion of the moon creates tides:

Tides Spring Neap

News from the Boston National Historical Park Twitter page.

boston NHP King Tides

News story from WCVB

http://www.wcvb.com/article/1065-foot-container-ship-breaks-free-from-boston-terminal/14186750

A container ship broke free from a terminal in Boston, the Coast Guard confirmed early Wednesday morning. The 1,065-foot ship “Helsinki Bridge” was at the Paul W. Conley Container Terminal when the 12 lines securing the vessel broke.

Helsinki Bridge container ship floats away

“They notified us very quickly. The ship’s crew was very quick in getting their engine equipment up and running so that they could drop their anchor and not be drifting around,” Coast Guard Lt. Jennifer Sheehy said.

Terminal workers who were on the ship were able to get off, and no injuries were reported. Two tug boats and a pilot helped to escort the runaway ship out to Broad Sound, between Winthrop and Nahant. State police said the ship hit a dock and did some minor damage when it broke free.

Paul W. Conley Container Terminal Boston

“They’ll take a look at all of the equipment.  They’ll talk to the ship’s crew, and a team is at Conley Terminal looking at any damage that might be there,” Sheehy said.

Officials said weather may have played a role in the ship breaking free.  “Winds that we had last night, the strength of those winds and a ship this size has a lot of sail area to push against, so it’s not unheard of for a ship this size to part ways because of the wind strength,” Sheehy said. The ship will eventually be towed back to the terminal.

See our lesson on tides, and Why Is There a Tidal Bulge Opposite the Moon?

Learning Standards

Ocean Literacy Scope and Sequence for Grades K-12

http://oceanliteracy.wp2.coexploration.org/ocean-literacy-framework/

Ocean Literacy Principle #3, The ocean interaction of oceanic and atmospheric processes controls weather and climate by dominating the Earth’s energy, water and carbon systems.

Ocean Literacy Principle #6,

b. The ocean provides foods, medicines, and mineral and energy resources. It supports jobs and national economies, serves as a highway for transportation of goods and people, and plays a role in national security.

f. Much of the worlds population lives in coastal areas. Coastal regions are susceptible to natural hazards (tsunamis, hurricanes, cyclones, sea level change, and storm surges).

 

 

The Science and History of the Sea

Session 1: TBA at the USS Constitution Museum. Museum staff led.

Constitution Museum Charlestown (1)

Introductory movie (10 minutes)

  • Design your own frigate based on the templates of Constitution’s ship designer Joshua Humphreys: Students will produce drawings.
  • Made in America – what materials were used to create the USS Constitution? Students will create a list of 5 materials from the New England region.
  • Which of these woods is the hardest? Through dropping balls into difference woods, we can study the difference in how the ball bounces back. The kinetic energy of the rebounding ball is related to the amount of energy absorbed by the wood. See the difference between kinetic energy and potential energy.
  • Test your ship against other frigates in this hands-on challenge. Choose between three different types of ships for the ultimate test of size, speed and power: An interactive computer simulation.
  • What’s so great about copper? Learn about the metals used in construction
  • Build a ship: Assemble 2D pieces into a 3D model – how quickly can they accurately complete the task?
  • Construction and launch: View this video, and then explain how a ship is safely launched from a drydock into the ocean.  Students will demonstrate that they understand the procedure by writing a step-by-step paragraph explaining the sequence.
  • How can a ship sail against the wind? Through a hands on experiment, see how changing the angle of the sail affects the motion of the boat: Students should be able to explain in complete sentences how the same wind can make a ship move forwards or backwards.
  • On the 2nd story of the museum, operate a working block-and-tackle system. This uses a classic simple machine. It is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift or pull heavy loads. Back in the school building, we’ll review each of the classic simple machines.

On the 2nd story of the museum, operate a working block-and-tackle system. This uses a classic simple machine: pulleys with a rope or cable threaded between them, to lift or pull heavy loads.

pulley simple machine

 

Session 2: USS Constitution Visitor Center, Building 5

10 minute orientation video

Can you locate where our school is on the 3D Boston Naval Shipyard model?

As students tour the visitor center, they practice ELA reading and writing skills (listed below) by briefly summarizing something they learn from each of these sections: They are encouraged to create drawings/tracings as they see fit to help illustrate their text.

  • Describe how ropes are made from string in the ropewalk
  • From wood & sail to steel & steam
  • Preparing for new technology
  • The shipyard in the Civil War
  • Ships and shipbuilding
  • The Navy Yard 1890-1974
  • Chain Forge and Foundary
  • The Navy Yard during World Wars I and II
  • Shipyard workers 1890 to 1974
  • The shipyard during the Cold War era 1945-1974

Session 4: Teaching math using the USS Constitition

Teaching math: Lessons from the USS Constitution

This teaching supplement contains math lessons organized in grade-level order. However, because many of the math skills used in these lessons are taught in multiple grades, both grade-level and lesson content are listed below.

Pre K–K 
Estimating Numbers of Objects

Grade 1
Estimating and Comparing Numbers of Objects

Grade 2
Estimating and Comparing Length, Width and Perimeter

Grade 3
Computing Time and Creating a Schedule

Grade 4
Drawing Conclusions from Data Sets

Grade 5
Creating and Interpreting Graphs from Tables

Grade 6
Range, Mean, Median and Mode and Stem-and-Leaf Plots

Grade 7
Converting Between Systems of Measurement

Grade 8
Calculating Volume

Algebra I (Grade 9–10)
Describing Distance and Velocity Graphs

Algebra I (Grade 9–10)
Writing Linear Equations

Algebra II (Grade 9–12)
Using Projectile Motion to Explore Maximums and Zeros

Precalculus & Advanced Math (Grade 10–12)
Using Parabolic Equations & Vectors to Describe the Path of Projectile Motion

Learning Standards

MA 2006 Science Curriculum Framework

2. Engineering Design. Central Concept: Engineering design requires creative thinking and consideration of a variety of ideas to solve practical problems. Identify tools and simple machines used for a specific purpose, e.g., ramp, wheel, pulley, lever.

Massachusetts Science and Technology/Engineering Curriculum Framework

HS-ETS4-5(MA). Explain how a machine converts energy, through mechanical means, to do work. Collect and analyze data to determine the efficiency of simple and complex machines.

Benchmarks, American Association for the Advancement of Science

In the 1700s, most manufacturing was still done in homes or small shops, using small, handmade machines that were powered by muscle, wind, or moving water. 10J/E1** (BSL)

In the 1800s, new machinery and steam engines to drive them made it possible to manufacture goods in factories, using fuels as a source of energy. In the factory system, workers, materials, and energy could be brought together efficiently. 10J/M1*

The invention of the steam engine was at the center of the Industrial Revolution. It converted the chemical energy stored in wood and coal into motion energy. The steam engine was widely used to solve the urgent problem of pumping water out of coal mines. As improved by James Watt, Scottish inventor and mechanical engineer, it was soon used to move coal; drive manufacturing machinery; and power locomotives, ships, and even the first automobiles. 10J/M2*

The Industrial Revolution developed in Great Britain because that country made practical use of science, had access by sea to world resources and markets, and had people who were willing to work in factories. 10J/H1*

The Industrial Revolution increased the productivity of each worker, but it also increased child labor and unhealthy working conditions, and it gradually destroyed the craft tradition. The economic imbalances of the Industrial Revolution led to a growing conflict between factory owners and workers and contributed to the main political ideologies of the 20th century. 10J/H2

Today, changes in technology continue to affect patterns of work and bring with them economic and social consequences. 10J/H3*

Massachusetts History and Social Science Curriculum Frameworks

5.11 Explain the importance of maritime commerce in the development of the economy of colonial Massachusetts, using historical societies and museums as needed. (H, E)

5.32 Describe the causes of the war of 1812 and how events during the war contributed to a sense of American nationalism. A. British restrictions on trade and impressment.  B. Major battles and events of the war, including the role of the USS Constitution, the burning of the Capitol and the White House, and the Battle of New Orleans.

National Council for the Social Studies: National Curriculum Standards for Social Studies

Time, Continuity and Change: Through the study of the past and its legacy, learners examine the institutions, values, and beliefs of people in the past, acquire skills in historical inquiry and interpretation, and gain an understanding of how important historical events and developments have shaped the modern world. This theme appears in courses in history, as well as in other social studies courses for which knowledge of the past is important.

A study of the War of 1812 enables students to understand the roots of our modern nation. It was this time period and struggle that propelled us from a struggling young collection of states to a unified player on the world stage. Out of the conflict the nation gained a number of symbols including USS Constitution. The victories she brought home lifted the morale of the entire nation and endure in our nation’s memory today. – USS Constitution Museum, National Education Standards

Common Core ELA: Reading Instructional Texts

CCSS.ELA-LITERACY.RI.9-10.1
Cite strong and thorough textual evidence to support analysis of what the text says explicitly as well as inferences drawn from the text.

CCSS.ELA-LITERACY.RI.9-10.4
Determine the meaning of words and phrases as they are used in a text, including figurative, connotative, and technical meanings

Common Core ELA Writing

CCSS.ELA-LITERACY.W.9-10.1.C
Use words, phrases, and clauses to link the major sections of the text, create cohesion, and clarify the relationships between claim(s) and reasons, between reasons and evidence, and between claim(s) and counterclaims.

CCSS.ELA-LITERACY.W.9-10.1.D
Establish and maintain a formal style and objective tone while attending to the norms and conventions of the discipline in which they are writing.

CCSS.ELA-LITERACY.W.9-10.4
Produce clear and coherent writing in which the development, organization, and style are appropriate to task, purpose, and audience.

External links

The USS Constitution Museum, located in the Charlestown Navy Yard, which is part of the Boston National Historical Park

From a Navy munitions bunker to a school

A new school is coming to Admiral Hill, steeped in the history of the city and sea. Founded in 1999, Seaport Academy understands that not all students learn the same way. Because learning issues can undermine confidence and a student’s willingness to engage with others, many students have missed out on important academic and social experiences. Seaport Academy was founded to give Boston area students an alternative path to success.

IMG_20170830_090358885

You won’t find many traditional classrooms at Seaport Academy – our students take advantage of the rich history of Charlestown, Boston and Chelsea, Massachusetts. We use Boston Harbor as part of the learning environment. We offer a collaborative, project-based, highly individualized approach to education that helps students meet their goals.

In our hands-on program, Seaport students weave together academic classes with exploration of the seafront, build bikes and chairs, experiment with aquaculture, learning fishing and boating, water chemistry experiments – and basketball. Hands-on, our experiential programs lets students rediscover what it means to enjoy learning, and to grow personally and academically.

Seaport Academy classroom. Photo by Richard Howard

Seaport Academy classroom. Photo by Richard Howard

By aligning our curriculum to the Massachusetts Curriculum Frameworks and setting clear and ambitious expectations, we give students the best opportunity to graduate, gain confidence and skills and advance successfully to college or careers.

This year, in 2017, Seaport Academy classrooms are moving to the Naval Hospital Boston Historic District, part of the National Register of Historic Places.

The school will be moving into the historic large ordnance building, built in 1830. At one time it held the USS Constitution’s munitions magazine. Since this is a historic building, it is being carefully adapted to house 21st century classrooms while fully protecting the historic structure.  Let’s take a look!

Here’s the outside of Chelsea Naval Magazine, Building #2.

Historic site turned into school

Here we see remodeling of the interior.

IMG_20170829_110806877

Transforming the space into a classroom.

IMG_20170829_111036839

More progress

Seaport Academy renovation

Seaport Academy renovation

Read more

Naval Hospital Boston Historic District

Naval Hospital Boston Historic District (Chelsea Naval Hospital)

Charlestown Navy Yard Historic Resource Study, by the National Park Service

The USS Constitution Museum, located in the Charlestown Navy Yard, which is part of the Boston National Historical Park

The USS Constitution, the oldest commissioned warship afloat. Official US Navy website

 

Mirages

A mirage is a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky.

The word comes to English via the French mirage, from the Latin mirari, meaning “to look at, to wonder at”. This is the same root as for “mirror” and “to admire”.

In contrast to a hallucination, a mirage is a real optical phenomenon that can be captured on camera, since light rays are actually refracted to form the false image at the observer’s location.

What the image appears to represent, however, is determined by the interpretive faculties of the human mind. For example, inferior images on land are very easily mistaken for the reflections from a small body of water.

Mirages can be categorized as:

“inferior” (meaning lower)

“superior” (meaning higher)

“Fata Morgana”, one kind of superior mirage consisting of a series of unusually elaborate, vertically stacked images, which form one rapidly changing mirage.

Mirage. (2016, December 18). In Wikipedia, The Free Encyclopedia.

Problems

According to legend, Erik the Red sailed from Iceland and discovered Greenland after he had seen the island in a mirage. Describe how the mirage might have occurred.

Erik The Red Mirage Greenland

Well, that answer from our textbook teacher editions, however true, isn’t very helpful. It’s not clear what we are looking at. Let’s look at a much better picture to see both the problem and the solution.

Problem: Erik the Red shouldn’t be able to see Greenland from where he is standing, on Iceland. Greenland is so far away that it is over the curve of the Earth (over the horizon.)

Solution:

The superior mirage, also know in northern polar regions as the arctic mirage — or in Icelandic, the hillingar effect — causes the light from distant objects to be optically refracted downward

Thus it becomes possible for objects lying beyond the normal horizon to be seen.

(They even appear, at times, to rise up over the horizon, a condition known to mariners as looming, and look much closer in distance.)

Fata Morgana Mirage in Greenland, 1999, by Jack Stephens

Fata Morgana Mirage in Greenland by Jack Stephens

SEE BELOW FOR THE FAMOUS MOBY DICK MIRAGE

superior mirage arctic

The arctic mirage, on the other hand, occurs when the light rays are refracted downward by cold, dense air near the earth into an arc bending toward the observer. (In the diagrams accompanying this article, the dark lines indicate the actual light ray path and the white dashed lines the path our mind thinks it sees.)

The refractivity of air — a measure of the air’s ability to bend the path of light rays — is dependent upon its density, and the density of air is inversely related to its temperature (decreasing as temperature increases). The atmospheric conditions for producing the arctic mirage occur when cool air adjacent to the surface underlies warm air. When the air temperature increases with altitude, the condition is known meteorologically as a temperature inversion.

When the temperature of the lower atmosphere increases with altitude at a rate of 11.2 C° per 100 metres (6.0 F° per 100 ft), the refractive capacity of the air is great enough to cause the path of light rays to bend in an arc equal to the curvature of the Earth. This curvature can present an observer with the image of a flat horizon receding to infinity. A temperature gradient greater than 11.2 C° per 100 m causes light ray paths to exceed the curvature of the Earth, and thus the horizon would appear to be raised upward giving the Earth’s surface a saucer-shaped appearance. Under this latter condition, images of objects located at or below the normal optical horizon, such as mountains, glaciers, cliffs or sea-ice rise (loom) into the field of vision, overcoming the normal visual restrictions of the curvature of the Earth.

The normal viewing distance at the surface of the earth depends upon the height of the object being observed and the height of the observer. Disregarding atmospheric effects on light rays, the curvature of the earth restricts the distance one can see from the surface. For example, a beach or small iceberg rising 3.0 to 3.7 m (10 to 12 ft) above the sea surface can be seen from the surface at a distance of no more than 19.2 km (12 miles) through a clear, normal atmosphere. A mountain peak of 914 metres (3,000 feet) would disappear at 115 kilometres (72 miles) distant, one 1520 m (5,000 ft) tall at 150 km (94 miles).

The maximum viewing distance under arctic mirage conditions, on the other hand, is limited only by the light absorption of the atmosphere. Near sea level, the transmission of light is generally of sufficient quality to enable the naked eye to potentially see objects at a distance of up to 400 km (250 miles). However, when the refracting layer is at the upper boundary of a very deep cold layer, the thinner air may permit more light to be transmitted, thus making visibility in excess of 400 km possible.

superior mirage arctic Greenland Iceland

Under arctic mirage conditions, instances of atmospheric visibility extending 320 km (200 miles) have been reported. In 1937 and 1939, W.H. Hobbs documented several occasions during which objects were sighted at distances well in excess of those possible under normal viewing conditions.

Answer text from The Arctic Mirage. Aid to Discovery. The Weather Doctor.

Moby Dick illusion

James Rickards writes

One famous literary description of a Fata Morgana occurs in Chapter 135 of Herman Melville’s masterpiece, Moby Dick. As Ahab is pulled overboard, and the White Whale rams the Pequod, Melville writes:

“The ship? Great God, where is the ship? Soon they through dim, bewildering mediums saw her sidelong fading phantom, as in the gaseous Fata Morgana.”

But, of course the ship was sinking, the vision was an illusion.

Chapter 135 Herman Melville Moby Dick

Amazing examples

A Ship Floating In Mid-Air At A Scottish Golf Tournament?

Images from Why Was There A Ship Floating In Mid-Air At A Golf Tournament? BuzzFeed

Just like the above mentioned mirages!

Tom Phillips BuzzFeed ilyast syntika Thinkstock Mirage

Enter a caption

image: Tom Phillips/BuzzFeed/ilyast/syntika/Thinkstockscottish-golf-tournament-floating-ship-mirage Aberdeen Open

Floating boats and islands

Video

Island and fishing boat mirage

Fata Morgana Mirage at Cocoa Beach, FL!

https://www.youtube.com/watch?v=VcEn3jb3oq4

Lake Superior Marquette, MI 05.23.15 – first scene is real time, freighter in to Marquette, second is timelapse, Granite Island looking like a lava lamp

https://www.youtube.com/watch?v=xJfJTdy2Ge8


External links

An Introduction to Mirages, Andrew T. Young

Fata Morgana between the Continental Divide and the Missouri River

Learning Standards

2016 Massachusetts Science and Technology/Engineering Curriculum Framework

HS-PS4-3. Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described by either a wave model or a particle model, and that for some situations involving resonance, interference, diffraction, refraction, or the photoelectric effect, one model is more useful than the other.

A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012)

Core Idea PS4: Waves and Their Applications in Technologies for Information Transfer
When a wave passes an object that is small compared with its wavelength, the wave is not much affected; for this reason, some things are too small to see with visible light, which is a wave phenomenon with a limited range of wavelengths corresponding to each color. When a wave meets the surface between two different materials or conditions (e.g., air to water), part of the wave is reflected at that surface and another part continues on, but at a different speed. The change of speed of the wave when passing from one medium to another can cause the wave to change direction or refract. These wave properties are used in many applications (e.g., lenses, seismic probing of Earth).

The wavelength and frequency of a wave are related to one another by the speed of travel of the wave, which depends on the type of wave and the medium through which it is passing. The reflection, refraction, and transmission of waves at an interface between two media can be modeled on the basis of these properties.

All electromagnetic radiation travels through a vacuum at the same speed, called the speed of light. Its speed in any given medium depends on its wavelength and the properties of that medium. At the surface between two media, like any wave, light can be reflected, refracted (its path bent), or absorbed. What occurs depends on properties of the surface and the wavelength of the light.

SAT Subject Area Test in Physics

Waves and optics:

  • Reflection and refraction, such as Snell’s law and changes in wavelength and speed
  • Ray optics, such as image formation using pinholes, mirrors, and lenses

Also see Benchmarks: American Association for the Advancement of Science