When does a Doppler speed log indicate speed...

When does a Doppler speed log indicate speed...

Question 1 of 2707066636ee928f7522a1c5195ff

When does a Doppler speed log indicate speed over ground?

Question 1 of 27070

Q

When does a Doppler speed log indicate speed over ground?

🔍 Key Concepts

• Doppler speed log operating modes (water track vs. bottom track) • Difference between speed over ground (SOG) and speed through the water (STW) • How water depth affects whether the Doppler return is from the seabed or from particles in the water column

💭 Think About

• Which operating condition or mode allows the Doppler log to measure motion relative to the seabed instead of relative to the water? • In what depth range can the Doppler signal reliably reflect off the bottom to give a usable ground reference? • How would current affect a log that measures speed through the water versus one that measures speed over ground?

✅ Before You Answer

• Identify which option corresponds to using bottom tracking rather than water-mass (volume reverberation) tracking • Check whether current prevents or simply changes the difference between speed through water and speed over ground • Consider the practical depth limitation beyond which the echo from the seabed is too weak for accurate bottom tracking