Errors of Echo Sounder?

DWQA QuestionsCategory: Function 1Errors of Echo Sounder?
george Staff asked 4 years ago

Echo Sounder Errors
 

  • Propagation Error: The Velocity Of Sound Increases When Temperature, Pressure & Salinity Increase. Due To High Salinity In Red Sea, Depths To Be Increased By 5%.
  • Aeration: Caused By Bubbles In The Water Due To:
  1. V/L Going Astern.
  2. Moving Rudder Hard Over.
  3. Air Pockets Left Over By Bad Weather.
  4. Breaking Water Over Shoal.

            Air Bubbles Reflect The Sound Waves Resulting In False Echoes.

  • Multiple Echoes: In Shallow Waters Echoes May Be Received From The First, Second & Third Reflections From The Sea Bed. Correct Echo Is The First One, Second & Third To Be Ignored.
  • Pythagorus Error: This Error Occurs If The V/L Has Two Transducers, One A Transmitter & The Other A Receiver. Distance Travelled By Sound Is More Than Actual Depth Of Water Below Keel. More Pronounced In Shallow Waters.
  • False Bottom Echoes: This Occurs In Deep Waters When An Echo May Be Received After The Stylus Has Completed One Rotation & Begun Another.

 

1 Answers
george Staff answered 4 years ago

 

  • Propagation Error: The Velocity Of Sound Increases When Temperature, Pressure & Salinity Increase. Due To High Salinity In Red Sea, Depths To Be Increased By 5%.
  • Aeration: Caused By Bubbles In The Water Due To:
  1. V/L Going Astern.
  2. Moving Rudder Hard Over.
  3. Air Pockets Left Over By Bad Weather.
  4. Breaking Water Over Shoal.

            Air Bubbles Reflect The Sound Waves Resulting In False Echoes.

  • Multiple Echoes: In Shallow Waters Echoes May Be Received From The First, Second & Third Reflections From The Sea Bed. Correct Echo Is The First One, Second & Third To Be Ignored.
  • Pythagorus Error: This Error Occurs If The V/L Has Two Transducers, One A Transmitter & The Other A Receiver. Distance Travelled By Sound Is More Than Actual Depth Of Water Below Keel. More Pronounced In Shallow Waters.
  • False Bottom Echoes: This Occurs In Deep Waters When An Echo May Be Received After The Stylus Has Completed One Rotation & Begun Another.