Midterms Notes Nav 3 PDF

NAUTICAL CHARTS 3. Coastal Chart - 1:75,000 to 1:350,000 Navigational Chart – representation in reduc...

NAUTICAL CHARTS 3. Coastal Chart - 1:75,000 to 1:350,000 Navigational Chart – representation in reduced form on flat surface of - For nearshore navigation, entering bays/harbours, and larger area of navigable water on surface of Earth. inland waterways. 4. Approaching Chart - 1:25,000 to 1:75,000 Types of Charts - Intended to help approach harbours and feature hazards to avoid accidents A. Small Scale Chart 5. Harbor Chart - Offer lowest detail but cover largest area - 1:5,000 to 1:25,000 - Scale from 1:75,000 to 1:5,000,000 - Largest scale charts show most detail for harbor approaches - Rave less details, more scale error, used for offshore and longer 6. Berthing Chart trips - Less than 1:5,000 - Not show all marks/hazards, and not suitable for planning - Used for navigating harbor and maneuvering pier or wharf harbour approaches - ERROR: 25ft. up to 100ft. for 1:100,000 chart --------------------------------------------------------------------------------------------------- B. Large Scale Chart Chart Projection – a systematic transformation of latitudes and longitudes, - Provides more detail and higher resolution, cover most local objects and information on a curved surface to a flat surface. hazards - Scale up to 1:75,000 Projection – means placing light source inside transparent globe and - Used for coastal planning projecting shadows for meridians, parallels, and other features onto a - Frequently resurveyed with updates in Notice to Mariners sheet of paper placed tangent to globe. (NTM) Position of light source can be: Transferring image of earth and irregularities on plane surface, --------------------------------------------------------------------------------------------------- a. Gnomonic – light source at center. factors involved: b. Stereographic – light source at antipode of point of tangency. 1. GEOID – rendition of 1. Sailing Chart c. Orthographic – light source at infinite irregular spheroidal - Greater than 1:1,500,000 distance from point of tangency. shape of the Earth. - Smallest Scale Chart 2. An ELLIPSOID – geoids are then transferred to - Planning, fixed position at sea, plot DR position in long voyages regular geometric Properties of Map Projection reference surface. 2. General Chart 3. Projection – ellipsoid, 3 - 1:350,000 to 1:500,000 1. Conformality – light source at center. dimensional 2. Equidistance – light source at antipode of - For coastal navigation well – offshore but with fixed landmarks, point of tangency. transformed into two- dimensional plane. lights, buoys and characteristics sounding/depth 3. Equivalency – light source at infinite distance from point of tangency.  Classification of Map Projections 4. Alber Equal-Area Conic - Equal area map uses to standard parallels, although scale and 1. Nature of projection surface defined by geometry. shape not preserved, distortion is minimal between standard 2. Coincidence of contact of projection surface with datum surface. 3. Position or alignment of projection surface with relation to datum parallels. surface. --------------------------------------------------------------------------------------------------- 4. Properties of cartographic requirements, and 5. Mode of generation of datum surface and coordinate systems. CHART READING How to use Nautical Chart: THREE MAIN TYPES OF MAP PROJECTIONS 1. Cylindrical Projection – it is like wrapping a sheet of paper onto the globe and transfer features to the sheet. 2. Conic Projection – method of projecting maps on surrounding cones, flattened to surface having concentric circles as latitudes and lines from apex meridians. Cone placed over the Earth 3. Arizmuthal Projection – a flat paper supposes to touch globe at one point and project lines of latitude and longitude on plane. Point of contact can be NP (North Pole) and SP (South Pole), Equatorial (Equator), or any point between (Oblique). COMMONLY USED MAP PROJECTION 1. Mercator Projection - Has straight meridians and parallels that intersect at right angles, measure distance at latitude and true only along equator, used in navigation for maps of equatorial regions. Distortion of poles. 2. Universal Transverse Mercator (UTM) Grid - Horizontal position representation, identify locations of Earth, divide Earth to 60 zones, each six degrees of longitude. 3. Lambert Conformal Conic - Seats a cone over Earth and projects conformally to cone, unrolled and parallel touching sphere. The colours on a nautical chart indicate the depths and types of seabed. COMMON PARTS OF THE NAUTICAL CHART Here is what each colour represents: White represents deep water, when you are off the coast Blue represents shallow water, between 0 and 10 meters. The darker the blue, the less water there is. You are therefore getting closer to the shoreline Green indicates the foreshore. In other words, the strip of coastline that is covered at high tide, but uncovered at low tide A yellow brown indicates the shoreline Pink represents the lighthouses at harbor entrances, underwater cables and restricted areas These markers indicate characteristics of the waterbed which is important when anchoring. S Sand Capital Letters indicate the type of bed: R Rock, Rocky M Mud Wd Weed (including kelp) Sh Shells (skeletal remains) St Stones G Gravel P Pebbles Bo Boulders Co Coral and Coralline algae CORRECTION AND UPDATING NAUTICAL CHARTS NOTICE TO MARINERS (NTM) - Sytematic process aimed at updating and maintaining accuracy - Provide timely and critical information to mariners for of nav charts used by navigators for safe voyage. correction and updating charts and publications, to have a safe voyage (Weely or Annually) WGS84 DATUM 2. World Port Index (PUB 150) - Comprehensive geodetic reference system serves as backbone - Contains tabular listing of ports, including location, for global positioning and navigation technologies. characteristics, facilities, and available services. - Developed by US Defense, Standard reference framework for GPS. Comprises of four different things: a. Ellipsoid Datum – Since earth is not perfectly spherical, and has flat on poles, an has defined radius on equator. b. Horizontal Datum – When we plot our geographical location on our 2-dimentional charts. c. Vertical Datum – Elevation and depth of surroundings, contour lines. d. Coordinate system – Has longitude based on Greenwich and latitude on equator. --------------------------------------------------------------------------------------------------- NAUTICAL PUBLICATIONS - Set of publication used for safe navigation of ships. Commonly Used Publication ON BOARD: 1. Sailing Directions - Details of harbors, ports, navigational hazards, local info, pilotage requirements. - Issues 76 Volumes.