Fund of navigation

Mid term study guide

Great circle

Shortest distance between two points but you have to change directions

Rumb lines

Longer distance but no changes in directions

Mercator projection

Lines are straight, long + lat intercept at 90deg, accurate in size along the equator, position, distance, direction is easily measured

Gnomonic projection

Used for long distance route planning, light through a globe

Small scale

shows a large area so it has less detail

Large scale

shows small area so it has more detail

Notice to Mariners

Provides safety updates so mariners can keep their charts updated. International charts

Local notice to mariners

primary distribution of info about aids to nav, hazards and other info. Small scale local charts

Green buoys

“Cans”, odd numbers

Red buoys

“Nuns”, even numbers

Mariners cross

Log chart updates here. Left corner, put date and initials under LNT/NTM

Electronic Charts updates

Updated by CDs, Downloading corrections, manual correction, Is up to date if updated within 45 days

Horizontal datums

Position, long/lat

Vertical datums for soundings

Usally Mean Lower Low Water

Vertical datums for heights

Usally Mean High Water

Datum

A plane of references that forms the basis for measurements on a chart

NAD 83 - North American datum of 1983

Is used by NOAA charts. Uses the Geodetic reference system GRS 1880

World Geodetic System

used by GPS and NGA charts. WGS84 

Datum shift

Anytime your positioning datum doesn’t match the chart datum

Waypoints

Location you want to pass through

Tracklines

The straight line btw your waypoints

Trackline lables include

1. Course in T

2. Course in M

3. Speed in KTs

4. Distance in NM

Track

The intended path of movement

Course

The direction a vessel is being steered or will be steered

Heading

The direction a ship points

Yaw

To twist

Cross track error

Lateral separation from the trackline “right of track” 

Orange triangle

Radar Nav aid

Yellow circle

Visual Nav aid

Fix

When 3 Lops intersect can be radar or visual. We plot as a circle/triangle with a dot, time written horizontally

Estimated position

When you only have 2 LOPs. Plotted with as a square with a dot, time written horizontally

DR

Is the approximation of our ships position based on a last known point. Drs tell us where we should be at the next fix

6 rules of DR

1. Every hour on the hour

2. Every course change

3. Every speed change

4. Every fix or running fix

5. Every LOP

6. Draw a new course line from each fix or running fix

Safe water buoy; marks safe start of channel

Red + White, with 1 ball and a white light

Isolated danger buoy; marks danger

Black + red with 2 balls and a white light

Preferred channel buoy; top color shows prefered side

Red and green light red + green light

Special purpose

Yellow with a yellow light

Lateral system

Marks the sides of channels

Cardinal system

Marks where you shouldn’t good

IALA

International association of Marien aids to navigation and lighthouse authorities

Fixed light

Light is always on

Flashing light

Light is off more then it is on

Light occulting

Light is on more then it is off

Isophase light

Light on + off is equally

DNC boundary

World

General only

1: 40 million

Coastal + General

1: 20 Million

Approach, Coastal, General

1: 10 million

Harbors, Approach

1: 5 million

All charts max level

must be greater the 1: 5 million

CG- ECDIS/VEGA

Designed to display maximum visibility of the chart

SINS/ SINS-2

Scalable integrated navigation system- specifically designed for CG. Particularly used in SAR

Navigation Evaluators Report

Provides an evaluation of the navigation system un narrative form

Advance

Is the distance traveled in its initial direction during a turn

Transfer

The distance traveled perpendicular to its initial direction during a turn

Tactical Diameter

The width of the first 180 deg of a ships turn

Final Diameter

The width of a ships turns after the first 180 deg, always less then tactical

Slide bar

A Stright line drawn through the turn point, parallel to the new track line

Turn bearing

Off the beam

Turn range

Off bow and stern

Set

Is the direction in which a vessel deviated from track. Measured in T, from DR to fix, every fix interval

Drift

The speed at which a vessel deviates from track. Measured in KNTs, from DR to fix, every fix interval

Diurnal tide

1 high/ 1 low tide each day

Semidiurnal

2 high/ 2 low tides each day - same height

Mixed semidiurnal

2 high/ 2 low tides each day at different Hights

Spring tides

Large tides, when the sun and moon align. 2 each month

Neap tide

Lowest tides when the sun and moon are 90 deg apart. 2 each month

Depth beneath the keel

Charted depth + height of the tide - draft

calculating true-magnetic-psc

Truly valiant marines don’t cry at weddings

Course made good

The net direction from one fix to another fix, measured in deg T

Speed made good

The net result speed from fix to fix, measured in KNTs

Ocean currents

current caused by environmental causes specifically wind

Tidal currents

Currents that are caused by tides

Eb

water flowing out

Flood

Water flowing in