• What Are Pilot Charts? Pilot Charts provide the navigator with averages. Averages concerning prevailing winds and currents, air and sea temperatures, wave heights, ice, visibility, barometric pressure, and weather conditions. There are five volumes of Pilot Charts, each being its own publication, and each covering a specific geographic region. Each publication is actually a compilation of twelve individual pilot charts, one for each month of the year. Pilot charts are intended to aid the navigator in selecting the fastest and safest routes with regards to the expected weather and ocean conditions. Pilot Charts are not intended to be used for navigation, however, they are invaluable in planning stages of a…

• Plotting Tool Options There is a wide array of tool options to assist you in navigation plotting. All have pluses to recommend them as your “go to” tool. Unfortunately, all also have cons that make them less desirable or more challenging to use. This tip is specifically how to use navigation protractor triangles (just call them triangles). For a discussion of the plusses and minuses of the other options, check out the lesson on “Navigation Tools – Plotting Tools“ Using Navigation Triangles Why Triangles (aka: What is a Protractor) Before we talk about why I prefer using triangles over the other plotting tool options available to me, let’s talk about…

• Finding Latitude and Longitude Lines of latitude run east and west (across the chart). Lines of longitude run north and south (up and down). Degrees of Latitude Zero degrees of latitude is known as the equator. Latitude goes from zero degrees to 90 degrees north and south of the equator. As can be seen in the image above, Lines of latitude run parallel to each other. There are 60 nautical miles between each degree of latitude. Lines of latitude are a consistent distance apart, so they can be used to measure distance. One degree of latitude can be divided into 60 “minutes”. Each minute of latitude is one nautical mile.…

• Calculating Wind from Isobars by Table Lookup There are at least two formulas I know of to estimate wind speed based on spacing of isobars on a surface analysis. Both are based on the relationship between pressure gradient (e.g. millibars per degree) and the latitude of interest. For those that are interested, a discussion of each follows. Fortunately, it is much easier to use a table where someone else has done the math for you. Calculating Wind Speed Measurement of the spacing of isobars can be done manually, or with the assistance of a tool. Here, a Surface Analysis of the Northeastern Pacific was loaded and displayed using OpenCPN, a…

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• What is Wind The title of this topic might have been “What causes the wind.” Quite simply, wind is moving air. Air doesn’t seem like much, however, it has weight and it has substance, and is actually considered a fluid. This becomes apparent when air moves. While moving, you can see many of the same characteristics you might find in a river. Things like moving as a “unit,” parting and coming back together as it flows around an obstacle, and eddies or back-flows. Air moves from an area of higher pressure into an area of lower pressure. The closer together the high and low pressure is and the greater the…