Charts and Tides Flashcards
What does SOLAS Stand for
Safety Of Life At Sea
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What two factors determine the Maximum Ranges of Lights?
The light must be powerful enough to be seen ( Luminous Range)
The light must be above the horizon (Geographical Range)
What is Nominal Range and where can it be found
The luminous range when meteorological visibility is 10 miles.
It can be found in the characteristics of the light given on the chart or column 6 of the admiralty list of lights and fog signals
What is luminous range
The maximum distance at which a light can be seen at a given time
Determined by the intensity of the light and the meteorological visibility at the time
Doesn’t account for: elevation, observers height of eye or earth curvature
Calculated using a he luminous range diagram
What two different levels is charted elevation measured from
Floating lights - sea level to the focal plane of the light
Lighthouses - MHWS to the focal plane of the light
What is Geographical Range
The maximum distance, at which light from a lighthouse can theoretically reach an observer, limited only by earth’s curvature, refraction of atmosphere, elevation of light and height of eye of the observer
A Fix is Indicated with …
A small circle, and, if possible, a time
Positions of Lighthouses are taken from…
The centre of the circle within the star shape
How is an Observed Bearing Shown on a Chart
A line with a single open arrow head away from the object
When “Suffering the Effects”, is the leeway taken into account for the water track
Yes
What is Water Track
The ships heading + or - the leeway
What is the Ground Track
Course in straight line
What does this symbol mean
Depth unknown, but is at least depth shown
What Symbol is this
Wreck at least depth shown, swept by wire drag
What Symbol is this
Wreck, last depth known obtained by sounding only
What Symbol is this
Visible Wreck
What Symbol is this
Visible Wreck
What Symbol is this
Wreck, least depth unknown but usually at least 20m
What Symbol is this
Wreck, least depth unknown but usually at least 20m
How do you plot a GPS fix on a chart
Just plot the lat and long given on the GPS (most basic plotting)
What Plotting Technique is it when you use Things you can See to take a Bearing
Visual Bearing Lines
What needs to be done to a compass bearing before it can be plotted on a chart
Convert it to a true bearing
How do you convert a Compass bearing to a True bearing
(TVMDC)<
Compass bearing
(+) Deviation Correction
(=) Magnetic Bearing
(Apply) Variation
(=) True Bearing
Where will you find the Deviation for True Bearing calculations
Deviation card (probably within the tide tables book)
How do you know if you should add or subtract Deviation
Look at current direction on compass and look at whether Deviation is east or west. EG: 90°C and Dev = 4°E, add 4+90
When adding or subtracting variation should you leave it as degree’s and minutes
No, convert it to decimals then add or subtract
When plotting a line from a visual fix, what should be added to the line
A single arrow head to show that the line could continue forever as we don’t know where on that line we are
What are Range lines marked with
An arrow at each end to indicate that the line could extend either direction
What should you add to fixing lines if given
The time which it was taken
When you have found your fix (where lines intersect) how should you mark it?
With a circle around the intersection (cross)
What is a transferred line marked by
Two arrows on one end
