The soundings on the chart are based on the...

Question 1 of 29218fork_d607c9b96b7c427bb03

The soundings on the chart are based on the depth of water available at __________.

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Question 1 of 29218

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The soundings on the chart are based on the depth of water available at __________.

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🔍 Key Concepts

• Chart datum used for U.S. nautical charts • Difference between mean low water, mean lower low water, and high water datums • Why soundings are usually referenced to a level close to the lowest predicted tide

💭 Think About

• Ask yourself: For safe navigation, should chart depths be measured from a higher water level or from a very low water level? Why? • Which of the listed water levels is typically used as the reference (datum) on U.S. coastal charts so that the mariner usually has at least that much water or more? • Compare "mean low water" and "mean lower low water": which one represents the lower average tide level in areas with two low tides per day?

✅ Before You Answer

• Verify in tide and chart references which level is the standard chart datum for U.S. charts (e.g., NOAA charts). • Make sure the option you pick represents a low-water reference, not a high-water reference. • Confirm that the chosen datum is defined as an average of the lower of the daily low waters over a 19-year period in mixed or semidiurnal tide areas.