Navigation General · Chart Datums & Projections
On a chart with a scale of 1:80,000, how does one nautical mile compare to one nautical mile on a chart with a scale of 1:20,000?
- AIt is represented by a longer line on the 1:80,000 chart
- BIt is represented by a shorter line on the 1:80,000 chart✓ Correct
- CBoth charts represent a nautical mile with the same line length
- DScale ratio does not affect the representation of distance
Explanation
A smaller denominator (1:20,000) means a larger scale — more paper per unit of earth, so features are larger and more detailed. A 1:80,000 chart (smaller scale) compresses more earth onto the same space, so one nautical mile is represented by a shorter line. Large scale = small area, great detail.
Authority: Bowditch (Pub. 9), Ch. 2
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