Why must the depth reading from a fathometer be calibrated against the hull reference to be accurate?

Why must the depth reading from a fathometer be calibrated against the hull reference to be accurate?

• A. Adjusted
• B. Calibrated
• C. Verified
• D. Compensated

Answer: (B)

Calibrating is the process that makes the depth readout match a known reference on the vessel. A fathometer measures distance from the transducer to the seabed, but navigational depth is usually referenced to a fixed point on the hull (like the keel or a designated hull reference). By calibrating, you determine and input the exact offset between the transducer and that hull reference, and the instrument is adjusted so the displayed depth corresponds to the true water depth at the hull reference. Without calibration, the reading can be off by the offset and any loading or trim changes, giving an inaccurate depth. Calibration establishes that standard so the depth reading is reliable for navigation and safety.

Calibrating is the process that makes the depth readout match a known reference on the vessel. A fathometer measures distance from the transducer to the seabed, but navigational depth is usually referenced to a fixed point on the hull (like the keel or a designated hull reference). By calibrating, you determine and input the exact offset between the transducer and that hull reference, and the instrument is adjusted so the displayed depth corresponds to the true water depth at the hull reference. Without calibration, the reading can be off by the offset and any loading or trim changes, giving an inaccurate depth. Calibration establishes that standard so the depth reading is reliable for navigation and safety.