When using an echo sounder in deep water, it...

Question 1 / 2707066636ee928f7522a1c51a536

Question 1 of 2707066636ee928f7522a1c51a536

When using an echo sounder in deep water, it is NOT unusual to encounter which situation?

Question 1 of 27070

When using an echo sounder in deep water, it is NOT unusual to encounter which situation?

🔍 Key Concepts

• Echo sounder returns in deep water and how multiple layers can create more than one echo • The effect of day vs. night on marine life and the deep scattering layer (DSL) • Difference between instrument error/recalibration issues and normal, expected phenomena

💭 Think About

• Ask yourself what natural changes happen between day and night in the ocean that could affect how sound is reflected back to the ship. • Consider whether a constant, unchanging false echo at the same depth would be more likely from a mechanical fault or a natural phenomenon. • Think about whether regular recalibration every couple of days sounds like a design expectation of modern echo sounders or a sign of something being wrong.

✅ Before You Answer

• Verify which option mentions a pattern that changes between day and night, matching how organisms or layers in the ocean move vertically. • Eliminate choices that clearly describe equipment malfunction rather than normal operational experience. • Check which choice best matches the idea of a secondary, strong return from something below the true bottom or from a migrating scattering layer in deep water.

Question 1 of 27070

When using an echo sounder in deep water, it is NOT unusual to encounter which situation?

Receiving false echoes at a constant depth day and night

Receiving a first return near the surface during the day, and a strong return at about 200 fathoms (366 meters) at night

Receiving a strong return at about 200 fathoms (366 meters) during the day, and one nearer the surface at night

To have to recalibrate every couple of days due to inaccurate readings

Question 1 / 2707066636ee928f7522a1c51a536

Question 1 of 2707066636ee928f7522a1c51a536

When using an echo sounder in deep water, it is NOT unusual to encounter which situation?

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Question 1 of 27070

When using an echo sounder in deep water, it is NOT unusual to encounter which situation?