Charting for Beginners

Essential Questions… How do you use a compass? How do you use a compass? How do you use the tools while charting? How do you use the tools while charting? What is the difference between bearing, course, and heading? What is the difference between bearing, course, and heading?

Why do we Chart A navigator is concerned with keeping the ship in navigable waters and fully afloat at all times. A navigator is concerned with keeping the ship in navigable waters and fully afloat at all times. As the ship approaches land, the risk of danger increases as the water becomes shallow and traffic increases. As the ship approaches land, the risk of danger increases as the water becomes shallow and traffic increases.

How do you use a compass?

Types of Compasses Gyro Compass Gyro Compass points to True North, is an expensive piece of equipmentpoints to True North, is an expensive piece of equipment Magnetic Compass Magnetic Compass points to magnetic northpoints to magnetic north the compass needle will attempt to align itselfthe compass needle will attempt to align itself red pole pointing toward magnetic north red pole pointing toward magnetic north blue pole toward magnetic south blue pole toward magnetic south

Variation Variation is the angle between the true and magnetic meridians at your present position Variation is the angle between the true and magnetic meridians at your present position Is different in different parts of the world Is different in different parts of the world It undergoes slight yearly changes It undergoes slight yearly changes it is the angle that the magnetic meridian is deflected east or west of the true meridian due to the effect of Earth's magnetismit is the angle that the magnetic meridian is deflected east or west of the true meridian due to the effect of Earth's magnetism is indicated on the compass roseis indicated on the compass rose

Compass Deviation Deviation is the difference between magnetic north and compass north Deviation is the difference between magnetic north and compass north is the amount that the compass needle is deflected from the magnetic meridian due to the effects of any "on board" magnetic fields is the amount that the compass needle is deflected from the magnetic meridian due to the effects of any "on board" magnetic fields it is not a constant error it is not a constant error compass deviation only changes as the ship's head changes, these are recorded on a deviation cardcompass deviation only changes as the ship's head changes, these are recorded on a deviation card

How do you use the tools while charting?

What is the difference between bearing, course, and heading?

Bearing the direction in which the object lays measured from a reference, bearings of objects are taken with north as reference and not the bow of the boat the direction in which the object lays measured from a reference, bearings of objects are taken with north as reference and not the bow of the boat the bearing of an object can have three different values the bearing of an object can have three different values

Relative Bearing an indication of direction with respect to the bow of the boat an indication of direction with respect to the bow of the boat can be indicated in one if two ways can be indicated in one if two ways "red" / "green" depending in the side if the ship that the bearing was taken on. Red meaning the port side. Green meaning the starboard side. The bow is 0 degrees and the stern is 180 degrees."red" / "green" depending in the side if the ship that the bearing was taken on. Red meaning the port side. Green meaning the starboard side. The bow is 0 degrees and the stern is 180 degrees. using 360 degree notation measured clockwise from directly in front of the bow. Uses three figures followed by the word relative.using 360 degree notation measured clockwise from directly in front of the bow. Uses three figures followed by the word relative. are used with unstabilized radar display. The direction of the ship's head must be found before relative bearings can be applied. are used with unstabilized radar display. The direction of the ship's head must be found before relative bearings can be applied.

Course is the direction in which you want your boat to proceed, usually designated True, Magnetic, or Compass, is set using north as a reference point is the direction in which you want your boat to proceed, usually designated True, Magnetic, or Compass, is set using north as a reference point

Heading is the direction in which your boat is moving at any particular moment is the direction in which your boat is moving at any particular moment

How can you find out where you are? Dead Reckoning Dead Reckoning Estimated Position Estimated Position Lines of Position (LOP) Lines of Position (LOP) Fix Fix

Dead Reckoning It is only an approximate position. It is only an approximate position. arrived at by allowing for the course the ship is steering and ship's speed through the water, forecast from the last known position of the ship. arrived at by allowing for the course the ship is steering and ship's speed through the water, forecast from the last known position of the ship. This position is indicated on a chart by a + and the time arrived at. This position is indicated on a chart by a + and the time arrived at.

Estimated Position is calculated using all known factors that may be affecting the ship's progress including the course steered, leeway, speed of the ship through the water, and the set and drift of the current. is calculated using all known factors that may be affecting the ship's progress including the course steered, leeway, speed of the ship through the water, and the set and drift of the current. It is indicated in a chart by a dot, indicating the actual position, surrounded by a triangle. It is indicated in a chart by a dot, indicating the actual position, surrounded by a triangle.

Lines of Position (LOP) is any line drawn on a chart on which the boat's position is known to lie. is any line drawn on a chart on which the boat's position is known to lie. This line can be obtained visually or electronically. This line can be obtained visually or electronically. Two lines are needed to determine the actual position, fix, of the ship. Two lines are needed to determine the actual position, fix, of the ship.

LOP can be obtained through a variety of methods see p 166 of reference guide. LOP can be obtained through a variety of methods see p 166 of reference guide. position lines drawn on the chart should have arrowheads to indicate how the line if position was arrived at. position lines drawn on the chart should have arrowheads to indicate how the line if position was arrived at. when using only two LOPs attempt to have the LOP cross at an angle of 90 degrees to each other. when using only two LOPs attempt to have the LOP cross at an angle of 90 degrees to each other. errors can result if the angle is cut less than 60 degrees or greater than 120 degrees errors can result if the angle is cut less than 60 degrees or greater than 120 degrees

Fix is the intersection of two or more lines of position. is the intersection of two or more lines of position. It is indicated on a chart by a dot with a circle around it, the dot represents the actual position of the ship at the time of observation. It is indicated on a chart by a dot with a circle around it, the dot represents the actual position of the ship at the time of observation. The ideal fix has three LOPs each cutting at 60 degrees to each other and all intersecting at a single point The ideal fix has three LOPs each cutting at 60 degrees to each other and all intersecting at a single point