Session II Nautical Charts 1 Objectives F To

Session II Nautical Charts 1

Objectives F To become familiar with data found on Nautical Chart and how it relates to GPS and the Ato. N Program. F To understand chart orientation. F To be introduced to the compass rose and understand variation error. F To become familiar with the data found in the General Information Block on a nautical chart. 2

F To understand how depths are depicted on a nautical chart. F To become familiar with the symbols and abbreviations found on a nautical chart. F To understand the scale of a nautical chart. F To be introduced to the horizontal and vertical datum on a nautical chart and their effect on GPS units and accuracy. 3

F To be introduced to the symbols that represent Aids to Navigation on a nautical chart. F To learn to read bottom characteristics on a nautical chart. F To help you understand the critical relationships between your GPS unit and a nautical chart. 4

One Minute of Latitude equals One Nautical Mile 5

GPS Note: Check that your GPS adjusts for VARIATION automatically! If not, you must set the VARIATION in your GPS. Review your “GPS Operation Manual” for the procedure for your GPS unit. 6

SMALL SCALE CHART EVERYTHING APPEARS SMALL – less detail. 1: 100, 000 MEANS 1 INCH ON THE CHART IS 100, 000 INCHES ON THE EARTH’S SURFACE. LARGE SCALE CHART EVERYTHING APPEARS LARGE – more details. 1: 1, 000 MEANS 1 INCH ON THE CHART IS 1, 000 INCHES ON THE EARTH’S SURFACE. 7

A Large Scale Charts provides a smaller area and more details. 8

1: 80, 000 Small Scale 1: 25, 000 Large Scale 9

Harbor Chart 1: 2, 000 1: 40, 000 10

Chart Orientation F TRUE NORTH is at the top of the chart. F EAST is at the right-hand side of the chart. F WEST is at the left-hand side of the chart. F SOUTH is at the bottom of the chart. 11

SC - Small Craft Chart F The Small Craft Chart is the exception to the rule. F True North orientation is not at the top of this chart. F Use the Compass Rose to orient True North on a SC Chart. 12

The Compass Rose F Every Rose. chart has a least one Compass F The star on the Compass Rose points to True North. F The outer circle projects True North, F The inner circle projects Magnetic North. 13

MAGNETIC NORTH TRUE NORTH VARIATION ERROR COMPASS ROSE 14

Magnetic North is 013 degrees to the West in the New York area. F The difference between True and Magnetic North is called Variation Error. F F Variation Error is printed in the center of the Compass Rose. F By using the latest charts, you will always have the latest up-to-date variation references. F Many newer GPS units automatically adjust for Variation Error. Check your GPS manual! 15

Chart Number F Located at the bottom left-hand corner of a nautical chart. F Chart Number is the official document number for the chart. F Edition Number is also shown. F Date of last Update indicates the last time that the chart was updated was 10: 00 AM on this date. 16

General Information Block 1. The Name reflects the body of water covered by the chart. 2. Vertical Datum - definition of how depths are measured on the chart. u Feet, Meters, or Fathoms (6 feet). Calibrate your depth sounder to this Datum. 17

Horizontal Datum Referyour to the General Update GPS with the Information Block on HORIZONTAL DATUM your Nautical Chart for referenced on the nautical the horizontal chart that you aredatum. using. WGS 84 18

F MLW - Mean Low Water - is the mean or average of the all of the low tide projections for the area. F MLLW - Mean Lower Low Water is the mean or average of the lowest tide projections for the area. – The lowest of the lows. – All charts are being changed to this datum. 19

Cautionary Notes F F A “Mean” is an average. Therefore, depths can be higher or lower than the printed depth shown on a nautical chart. Depths are also affected by storms, the moon, and shoaling in the area. – Onshore winds can increase the depth of water. – Offshore winds can decrease the depth of water and/or delay its predicted depth time. 20

F Depths found on nautical charts are best professional guesses. F Always use two methods for determining water depth. – A charted depth and a depth sounder are acceptable as long as the depth sounder is set to the vertical datum from the chart that you are using. F Before you start out on a trip, always calibrate (verify) the accuracy of your depth sounder. 21

Scale of the Chart - a ratio of inches on the chart to inches on the earth’s surface. – 1: 40, 000 means that 1 inch on the chart represents 40, 000 inches on the earth’s surface. Heights of Objects are measured in vertical datum above Mean High Water. – Clearance under bridges are measured up from the MHW projection. – Heights of lights are measured up from the MHW projection to the focal plane of the light. 22

F Special Abbreviations and Notes are shown that are peculiar to the area. Notes - special notes of uncharted dangers in the area. F Cautionary F Special Tide and Current Information - any unique tide or current phenomena in the area is noted. F Magnetic Interference in the area. F LORAN Interference in the area. F Anchorage Areas in the area. 23

Soundings and Water Depth F Depth designations are shown with: – Numbers which reflect the vertical sounding datum. – Colors - shallow water is tinted a darker blue and deeper water is a lighter blue and white. – Contour Lines - a system of standardized symbols and abbreviations - dots and dashes. 24

F Depths are expressed in: – Feet. – Meters. – Fathoms [Six Feet per Fathom] F All depths refer to the vertical datum of the chart. 25

Aids to Navigation F Symbols for Ato. Ns. – Diamond with a small circle. – Lighted ATONs show a magenta circle and a small circle. F Abbreviations for shape of Ato. Ns. – N - designates a nun or conical shaped buoy. – C - designates a can shaped buoy. 26

F Abbreviations the Ato. N. FR = red. that indicate color of Red - Diamond symbol will be printed F G = Green - Diamond symbol will be printed green. F RW = Red and White. . F GR = Green buoy with Red band. F RG = Red buoy with Green band. F Y =Yellow - When Ato. N is painted white or yellow, the diamond chart symbol is left white or blank. 27

F Abbreviations for Light color on Buoys: – R - Light is Red. – G - Light is Green. – Y - Light is Yellow. – When no color symbol is shown with a buoy, the light color is assumed to be white. F Other Features on Buoys: – Sound Signals - Horns, whistles, bells, and gongs. – RADAR Reflectors - reference is found only in the Light List. 28

– Numbers - Nuns are even numbered and cans are odd numbered. – Letters - Used on non-lateral buoys. – Light Flash Characteristics - how the light flashes. Note: The numbers or letters, and the flashing characteristics on the Aid are printed on the nautical chart beside the chart symbol. 29

Chart Symbols CAN - Green Diamond with small watch circle NUN – Red diamond with small watch circle. Watch circle overprinted with magenta when lighted. Italics used for buoys and other floating aids. 30

Symbols - Daymarks and Minor Lights Green Daymark Green square. Red Daymark Red triangle Minor Light - Magenta exclamation mark (teardrop) with black dot Vertical letters used for fixed marks 31

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F Symbols for Light Houses and Other Fixed Aids. – Major Lights - Light Houses. u Black Dot with a Flare - looks like an exclamation point. u Name of Light appears on the Chart. u Shows height and range of light. – Small Lights - Fixed Lights. u Black Dot with a Flare - looks like an exclamation point. u Not named on the chart. u Will show height and range. 34

Fixed Aids Small Light Major Light 35

F Ranges: – Consist of two daymarks or beacons. – Shows a dashed line in the direction of the range or safe water. – If not lighted, shows daymark symbols as squares or triangles. – Interpretation of panel colors is found in the front of the Light List. – If lighted, light symbols and flash characteristic appears on the chart. CAUTIONARY NOTE: Ranges are usually fixed on land, rocks, or shoals. Always use a nautical chart when transiting a range. 36

R A N G E 37

Range 38

F Isolated Danger Marks – Erected on or moored over a danger. – Horizontal bands of red and black. – White light. – Top mark of two black spheres. – Chart symbol has two black dots over the diamond symbol. 39

F Daymarks - Day Beacons – Permanently fixed structures. – Uses square, octagonal or triangle panels to designate their use. – TR and small triangle. u Red - Even numbered - Red light if lighted. u Treat as if a nun buoy – SQ and small square. u Green - Odd numbered - Green light if lighted. CAUTIONARY NOTE: Do not pass close aboard (near) daymarks due to the danger of striking their foundation. 40

Other Charted Features F Prominent Landmarks – Water towers, smoke stacks, church spires, flag poles, public buildings. – Symbol is a circle with a dot indicating a highly surveyed position. – Great for taking bearings. – Circle symbol without a center dot is an approximate position. – Landmarks on private property are not plotted on nautical charts. 41

F Wrecks, Rocks and Reefs. – May be shown as: u Symbol u Abbreviation plus a number. u Dashed or dotted line around a symbol. F Bottom characteristics – Symbol or abbreviation used alone or in combination. F Structures – Jetties, docks drawbridges, and ramps. – Some docks do not appear on a chart depending on the scale of the chart. 42

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F Coastlines – Identified at both high and low water. – Any prominent landmarks that may help you get a fix on your position may be shown. – Any details located a short distance from the shore line may not be shown. F Lettering on a Nautical Chart. – Vertical lettering indicates fixed objects. – Slanted lettering indicates floating objects. 44

Horizontal Datum F Accuracy is based on the survey that was made to generate the chart. – NAD 27 – NAD 83 WGS 84 u Has accuracy impact between your GPS Set and the nautical chart. . Your GPS set must be adjusted to reflect the datum of the Nautical Chart that you are using. 45

F Criteria used to determine the accuracy of a nautical chart. . – Source and date of the survey. – Amount of detail of the soundings in an area. – Blank spaces should be regarded with suspicion. – The term, “Dumping Ground”, indicates that material was dumped in the area and that soundings in this area have not been verified. 46

Chart Corrections Local Notice to Mariners found on internet http: //www. uscg. mil/d 1/navinfo. htm F Always start with the most recent LNM and work backwards F Temporary corrections are made in pencil F Permanent corrects are done in ink F 47

Electronic Equipment Notes F Set your Depth Sounder to the vertical datum from your chart—feet, meters, or fathoms. F Set your GPS to the horizontal datum from your chart--WGS 84. F If your GPS does not have an automatic variation adjustment, set it for the Variation Error found in the nearest Compass Rose. 48

Traffic Separation Scheme 49

End of Session II 50