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Thursday, February 25

  1. page Stellar Navigation edited Celestial (Stellar) Navigation ... Fortunately, when hiking in the wilderness, sailing, we …

    Celestial (Stellar) Navigation
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    Fortunately, when hiking in the wilderness,sailing, we often
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    find your way, even in places like New York City.way.
    Learning the Constellations
    Step 1There are a few constellations that every navigator should be aware of. In the Northern Hemisphere, these are the northern constellations of Cassiopeia and the Big Dipper. The Big Dipper and Cassiopeia are visible all year round, revolving around the North Star. Take some time to become familiar with these two constellations so you can spot them any month of the year. (Remember, the stars revolve throughout the year, so at some times of the year expect to find Cassiopeia upside down.)
    {Cassiopeia.gif}
    {BigDipper.gif}

    Step 2Enjoy learning about some of the other constellations as well. The zodiacal constellations mark the ecliptic, and their rising and setting can be useful for marking east and west, and determining the time and season of the year.
    Step 3Watch the phases of the moon, which is a very useful guide. The phases of the moon depend on its relationship with the sun. A full moon, for example, is in opposition to the sun, and will rise exactly as the sun is setting.
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    Step 1Once you've learned to recognize the Big Dipper, you can always find Polaris, the North Star. The Big Dipper somewhat resembles a frying pan, with a long handle and a rectangular head. Looking at the "head," imagine a straight line from the two furthermost stars (see diagram). The line should extend perpendicular to the tail of the Dipper, and will point directly toward the North Star. You now have north.
    Step 2Cassiopeia also points toward Polaris, and is on the other side of Polaris, opposite the Big Dipper. Polaris is almost equidistant between them. Cassiopeia resembles a W on its side. Polaris makes the form of an arrow with one of Cassiopeia's points. (See picture.)
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    around it. The picture below shows the Big Dipper rotating around the North Star.
    {Big_Dipper_Seasons.jpg}

    Determining Latitude
    Step 1Measuring the angle between the horizon and Polaris will provide your latitude. The North Star is on the horizon at the equator (0 degrees), and directly overhead at the North Pole (90 degrees). The angle drawn between the horizon and the North Star for any location will yield the latitude of the observer.
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    11:49 am
  2. file BigDipper.gif uploaded
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  3. file Cassiopeia.gif uploaded
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  4. page The Physics of Sailing edited ... When the wind is coming from the side It is easy to understand how Sails work when the Wind i…
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    When the wind is coming from the side
    It is easy to understand how Sails work when the Wind is coming from the back. When the Sails are let out, the Wind pushes them, driving the boat forward. If this is the case, then the Sailboat will move sideways if the Wind is coming from the side. But this can be avoided and the boat can move forward through the use of the Centerboard or Keel. It resists the sideways force, therefore preventing the Sailboat from moving sideways. Keep in mind that the Keel should be well-shaped to resist the sideways force.
    {http://www.abc-of-sailing.com/images/pics/sideways-force.gif}
    The Heeling Force The heeling force is the force of the wind that approaches the boat parallel to the direction of course. This causes the boat to tip sideways, and often the passengers must lean to the high side in order to keep the boat from capsizing.
    {heeling.jpg}
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  5. page The Physics of Sailing edited ... The Sideways Force The sideways force is also generated by the wind when it does not hit the …
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    The Sideways Force
    The sideways force is also generated by the wind when it does not hit the sail head on and pushes the vessel sideways. As the force that the wind presses into the sail does spread not only into the forward-direction (driving force), but partly also off the forward-direction, sideways forces are generated. The faster the boat is sailing, the smaller the sideways force. It becomes more apparent if the sail is pulled in too far. If you are sailing on upwind courses, you will always have to consider the effects of the sideways force – the drift off your steered course due to the sideways force is called leeway.
    When the wind is coming from the side
    It is easy to understand how Sails work when the Wind is coming from the back. When the Sails are let out, the Wind pushes them, driving the boat forward. If this is the case, then the Sailboat will move sideways if the Wind is coming from the side. But this can be avoided and the boat can move forward through the use of the Centerboard or Keel. It resists the sideways force, therefore preventing the Sailboat from moving sideways. Keep in mind that the Keel should be well-shaped to resist the sideways force.

    The Heeling Force The heeling force is the force of the wind that approaches the boat parallel to the direction of course. This causes the boat to tip sideways, and often the passengers must lean to the high side in order to keep the boat from capsizing.
    {heeling.jpg}
    (view changes)
  6. page The Physics of Sailing edited ... This is caused by the wind flowing across the sail, mostly the main sail and the spinnaker. To…
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    This is caused by the wind flowing across the sail, mostly the main sail and the spinnaker. To make good use of this force, it is important to keep the sail at a small angle to the wind – this is why constant trimming is crucial for optimizing the driving force. The angle requires simple adjustments.
    The forces around the mask are both the driving force and the sideways force. These two forces are vectors that sum up to the total force – the force that moves the boat. This movement occurs in the forward direction mostly, but should also move a bit sideways.
    {206254_sailboat_1.jpg}
    The Sideways Force
    The sideways force is also generated by the wind when it does not hit the sail head on and pushes the vessel sideways. As the force that the wind presses into the sail does spread not only into the forward-direction (driving force), but partly also off the forward-direction, sideways forces are generated. The faster the boat is sailing, the smaller the sideways force. It becomes more apparent if the sail is pulled in too far. If you are sailing on upwind courses, you will always have to consider the effects of the sideways force – the drift off your steered course due to the sideways force is called leeway.
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    9:06 am
  7. page Stellar Navigation edited ... (Stellar) Navigation There are a few constellations of which every navigator should be a…

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    (Stellar) Navigation
    There are a few constellations of which every navigator should be aware. In the northern hemisphere, the constellations Cassiopeia and the Big Dipper are visible all year round, revolving around the North Star.

    The practice of navigating by the stars is as old as antiquity. In the modern age, light pollution has reduced the night sky to only a few constellations. Fortunately, when hiking in the wilderness, we often find ourselves miles from any electric light source. Here we can appreciate the innumerable stars, watch the movements of the planets, and navigate by the constellations. A rudimentary knowledge of the stars can help you find your way, even in places like New York City.
    Learning the Constellations
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  8. page History of Sailing edited ... http://library.thinkquest.org/C003446/a.php?b=14 http://en.wikipedia.org/wiki/Privateer htt…
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    http://library.thinkquest.org/C003446/a.php?b=14
    http://en.wikipedia.org/wiki/Privateer
    http://www.mnh.si.edu/vikings/learning/teachersguide.html#02http://www.mnh.si.edu/vikings/learning/teachersguide.html#02http://www.cruise-charter.net/history-of-sailing/
    (view changes)
    9:02 am

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