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USCG Exam Practice · Applying tide corrections to charted depth

US nautical charts reference charted soundings to which vertical datum?

  1. AMean High Water (MHW)
  2. BMean Lower Low Water (MLLW)✓ correct
  3. CMean Sea Level (MSL)
  4. DMean Low Water (MLW)

Why B is correct

Bowditch Ch. 4 §403 states that US charts show soundings referenced to Mean Lower Low Water (MLLW). This datum represents the average of the lower low water heights, providing a conservative (shallow) reference for depth.

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US nautical charts reference charted soundings to which vertical da… — USCG Exam Practice · CaptainsGround