Coastal Navigation, Mike Pyzel Chapters 1 & 2

Latitude Parallels = loxodrome North = + (Plus) 5 major Latitudes The Arctic Circle (66° 33′ 38″ N) The Tropic of Cancer (23° 26′ 22″ N) The Equator (0°) The Tropic of Capricorn (23° 26′ 22″ S) The Antarctic Circle (66° 33′ 38″ S)

Longitude Meridians Great Circles (a circle on the surface of a sphere that has the same circumference as the sphere) Greenwich = 0 degrees = Prime Meridian Greenwich = South East London Borough West = - (minus) Hoofers = 43.077° N 89.4005° W = +43° 4' 37.20", -89° 24' 1.80"

Mercator Projection Is the standard map projection for nautical purposes because of its ability to represent lines of constant true bearing or true course, known as rhumb lines, as straight line segments. While the direction and shapes are accurate on a Mercator projection, it distorts the size. If you follow a given (magnetic-deviation compensated) compass-bearing on Earth, you will be following a rhumb line. All rhumb lines spiral from one pole to the other unless the bearing is 90 or 270 degrees, in which case the loxodrome is a line of constant latitude, such as the equator. Equator touches the cylinder Reasonable true shapes and distances if within 15 degrees of the equator Greatest distortion in high latitudes Why you cannot use Longitude scale to measure Nautical Miles

Other Projections Miller cylindrical projection azimuthal projection sinusoidal projection Robinson projection was adopted by National Geographic Magazine in 1988

Note: depths depth units contour lines Shallow water in light blue Buoys lights landmarks obstructions (wrecks) Compass rose

Chart Scales 60 minutes = 1 degree 1 minute Latitude = 1 Nautical Mile

Compass Rose 2007 Variation: 9 degrees, 50 min W 1986 Variation = 8 degrees W Annual Increase 2007 – 1985 = 22 * 5 Min. = 110 min = 1 degree, 50 min

Magnetic Variation Varies with time Liquid outer core is iron that moves

T-V-M-D-C True north refers to the north geographic pole of the earth, essentially the axis of the earth’s rotation Variation the difference between true north and magnetic north Magnetic north refers to the north magnetic pole which is some distance away from the north geographic pole and is constantly changing Deviation the error between magnetic north and compass north and refers to the inaccuracy of a particular compass on a particular boat on a particular heading Compass the direction pointed by a particular compass on a particular boat on a particular heading T + V = M M + D = C V & D West = + V & D East = - You can look at the compass rose to figure out that E = - & W = + Remember this acronym True Virgins Make Dull Companions falling down add Whiskey

Deviation Compass affected by iron, electrical wiring, & other parts of the boat

Determine your Compass Deviation You decide to calibrate your ship’s compass using a land range that lays on a bearing of 193°T. Magnetic Variation for your present location is 7°E. You motor across this range line on various headings and sight across the compass on each pass and record the following data

T-V-M-D-C How compass bearing would change if boat were on different headings

Navigation Tools Steering compass with deviation table Hand bearing compass and/or pelorus Binoculars Protractor or parallel rules Depth sounder or lead line Pencil, eraser and notebook Dividers Watch or clock Log / Knotmeter Simple Calculator

Hand Bearing Compass Can use the ship’s compass to do a rough bearing These compass are also subject to the boats deviation though not necessarily the same as the ship’s compass. This can change with the location on the boat the hand-held compass is used.

Pelorus A better way to use the ship’s compass for bearings is with a pelorus. Sight the object looking across the pelorus and the cross-hairs and read the relative bearing. Add or subtract this from the ship’s compass

Ploting a Latitude-Longitude Position Hold the parallel rules horizontally and accurately place them along an east-west line such as the bottom scale, which is parallel to the equator. Then press down firmly on the bottom rule and slide the top rule up the page; walk the rules up until the top rule aligns with the desired latitude. Draw a horizontal line; this is a line of latitude. Next, hold the parallel rules vertically and place them accurately along a north-south line such as the left hand scale; press down firmly on the left rule and slide the right rule to the right until it reaches the desired longitude. Draw a vertical line; this is a line of longitude. Where these two lines intersect is the position fix, which should be marked with a circle and dot and the time.

Ploting a Latitude-Longitude Position; Alternate Method An alternate method for drawing these lines using the dividers to measure the distance from a vertical reference line and marking a small pencil tick with the dividers. Then use the parallel rules, properly aligned, to draw a vertical longitude line. A similar procedure can be used to draw the horizontal latitude line.

Lines of Direction To draw a line of direction at a desired angle, lay the Parallel Rules through the center marker of the nearest compass rose and through the desired angle on either the True or Magnetic compass rose. Walk the Rules to where you want the line and draw it.

Lines of Direction; Alternate Method

Publications Coast Pilots: Published by NOAA giving similar details as noted in cruising guides. However, they are slanted more toward shipping rather than coastal cruisers, so some detail is omitted. Coast Pilots are an authoritative resource for information on weather, currents and hazardous conditions that exist in the coastal area. Coast Pilots come in several volumes covering U.S. Waters only. Light List: This USCG Publication gives details on all navigational aids in US. Waters. Of particular value is the description of lights, fog signals and radio beacons, including their characteristics. Five volumes cover U.S. Waters. They are updated annually. (www.navcen/uscg.gov/puhs/ LightLists/LightLists.htm). Notice to Mariners: Booklet published weekly containing corrections which apply to all charts and publications produced by the U.S. Government. This informatjon will later he included in new editions of each. (www.chartmaker.ncd.noaa.gov/rnccl/ Updates/index.htm) Tide and Current Tables: Tidal Differences and other Constants, Current Differences and other Constants, Indes to Stations (http://www.co- ops.nos.noaa.gov/tide_pred.html, http://www.co- ops.nos.noaa.gov/currents04/currpred.html) The US Notice to Mariners corrects NGA and NOS charts using information collected from many sources, among them the Local Notice to Mariners published by the various US Coast Guard districts. The US Notice to Mariners will contain only those chart corrections of interest to ocean going vessels.