Which of these is the larger-scale chart? Compare the chart scalesIllustrative · not to scale · tap to enlarge ↗ 1:100,000 1:10,000 Both have the same scale
Read the answer and explanation Answer: 1:10,000
Why this answer works 1:10,000 represents a smaller area per centimetre and is the larger scale.
Why the other choices fall short The denominator is not a score for detail: a larger denominator represents more ground in the same chart space. At 1:10,000, a feature is drawn ten times larger than at 1:100,000.
Put it into practice Write the ground distance represented by one centimetre on each chart. Use that comparison to choose coverage appropriate to the navigational task.
On a 1:10,000 chart, 2 cm represents… Measure the paper distanceIllustrative · not to scale · tap to enlarge ↗ 20 m 2,000 m 200 m
Read the answer and explanation Answer: 200 m
Why this answer works 2 × 10,000 cm = 20,000 cm, which is 200 metres.
Why the other choices fall short Two centimetres multiplied by 10,000 is 20,000 centimetres. Dividing by 100 gives 200 metres; the distractors are ten times too small or too large.
Put it into practice Keep the units unchanged until after multiplication. Write 20,000 cm = 200 m rather than dropping zeros mentally.
Zooming a screenshot creates… A closer viewIllustrative · not to scale · tap to enlarge ↗ A larger view of existing information Additional survey measurements An automatically updated chart
Read the answer and explanation Answer: A larger view of existing information
Why this answer works Enlargement changes display size; it does not add underlying survey detail or updates.
Why the other choices fall short Zoom changes how existing pixels or chart data are displayed. It does not commission a survey or apply an update to a saved screenshot.
Put it into practice Find the underlying product's edition and coverage rather than judging it by how sharp it appears. For an approach, obtain suitable current navigational information.
You find an unfamiliar chart symbol beside the route. What next? An unfamiliar chart symbolIllustrative · not to scale · tap to enlarge ↗ Assume it is decorative Look it up in the publisher’s symbol reference Ignore it if the route line misses its centre
Read the answer and explanation Answer: Look it up in the publisher’s symbol reference
Why this answer works Resolve the symbol before deciding what it means for your route.
Why the other choices fall short A symbol may describe a hazard with an extent beyond its printed centre. Appearance alone does not establish its meaning or whether your route has sufficient clearance.
Put it into practice Look up the exact symbol and associated abbreviations in the publisher's reference. Read nearby notes before deciding what it means for the planned track.
Which information belongs in a chart check? Check the chart informationIllustrative · not to scale · tap to enlarge ↗ Only the image resolution Only the date you downloaded it Edition, updates, scale, units and notes
Read the answer and explanation Answer: Edition, updates, scale, units and notes
Why this answer works The information must be suitable and current for the task, not simply easy to read.
Why the other choices fall short A recent download can contain old data, and a sharp image can still use unsuitable scale or units. File appearance and download time are not a chart's editorial history.
Put it into practice Check publication and update information, scale, sounding units and notes together. Record the sources used in the passage plan so the checks can be revisited.
Which task most needs detailed local chart coverage? Detail for the taskIllustrative · not to scale · tap to enlarge ↗ A harbour approach among shoals Comparing two ocean basins Choosing which state to visit
Read the answer and explanation Answer: A harbour approach among shoals
Why this answer works A confined approach calls for appropriate local detail as well as current notices.
Why the other choices fall short Broad geographic comparisons need coverage; a shoal-filled approach needs local detail. The right chart is chosen for the task rather than simply for its overall size.
Put it into practice Compare an overview with suitable approach coverage. Identify a feature important to pilotage that cannot be resolved adequately on the overview.
You are choosing between a 1:25,000 chart and a 1:100,000 chart for a harbour approach. Assuming suitable current coverage, which normally provides more detail? Choose the approach scaleIllustrative · not to scale · tap to enlarge ↗ Whichever is displayed on the larger screen The 1:25,000 chart The 1:100,000 chart Both must show identical detail
Read the answer and explanation Answer: The 1:25,000 chart
Why this answer works 1:25,000 is the larger scale: the same chart distance represents less ground. Choose suitable current harbour coverage and inspect its notes; screen size alone does not determine source detail.
Why the other choices fall short At 1:25,000 the same feature occupies four times the chart length it does at 1:100,000. A large screen does not change the underlying scale or guarantee equal detail.
Put it into practice Use the denominator comparison as a first check, then inspect coverage, notes and currency. A large-scale chart of the wrong place is still the wrong chart.
On a paper chart at 1:50,000, two points are 4 cm apart. What distance does that represent on the ground? Read the scale carefullyIllustrative · not to scale · tap to enlarge ↗ 2 km 200 m 20 km 2 nautical miles
Read the answer and explanation Answer: 2 km
Why this answer works 4 × 50,000 = 200,000 cm = 2,000 m = 2 km. The scale calculation gives a metric distance here, not nautical miles; use the appropriate chart scale for navigation.
Why the other choices fall short 200 m and 20 km are factor-of-ten conversion errors. Two nautical miles uses a different unit and is not the result of this centimetre-to-metre calculation.
Put it into practice Write 4 × 50,000 = 200,000 cm = 2,000 m = 2 km. If another unit is needed, perform that conversion explicitly as a separate step.
You enlarge a small-scale electronic chart until a narrow inlet fills the screen. What has the zoom definitely changed? Bigger on screenIllustrative · not to scale · tap to enlarge ↗ The age of the underlying survey The accuracy of every sounding The chart into a current harbour-scale survey The display size, without guaranteeing additional surveyed detail
Read the answer and explanation Answer: The display size, without guaranteeing additional surveyed detail
Why this answer works Magnification can make existing information easier to see but cannot create missing survey detail. Check the actual chart coverage, scale and currency before using it for a close approach.
Why the other choices fall short None of the other choices follows from enlarging a display. Survey age, sounding accuracy and available detail belong to the source data, not the zoom control.
Put it into practice Check whether the display is using suitable detailed coverage or merely enlarging smaller-scale information. Review the source and chart notes before relying on the view for pilotage.
A printed chart excerpt has been resized to fit a page, but still shows the original label 1:25,000. Can you safely use that printed ratio with a ruler without checking the resize? A resized printoutIllustrative · not to scale · tap to enlarge ↗ No; resizing can invalidate the printed ratio for ruler measurements Yes, because the printed number cannot change Yes, if the coastline still looks recognisable Yes, provided you use centimetres rather than inches
Read the answer and explanation Answer: No; resizing can invalidate the printed ratio for ruler measurements
Why this answer works The ratio relates physical lengths on the original chart to ground distances. Resizing changes those physical lengths without necessarily changing the text label. Establish a reliable scale before making a measurement.
Why the other choices fall short Recognisable shapes show that the image survived, not that its physical scale did. Changing ruler units does not undo a scaling change introduced during printing.
Put it into practice Use the original suitably scaled product or establish scale from a valid scale bar carried with the image. Do not use an unverified printout as navigational coverage.
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