| 摘要 |
A system is provided for the detection of an unsuitable water condition in which either large globules of solid material or bait fish suspended in the water beneath a vessel adjacent the hull of the vessel are detected and the associated depth sounding device is inhibited from providing a depth output. This eliminates the display or annunciation of erratic depth data, or the use of erratic data for closed or open loop control systems. In one embodiment, the unsuitable water condition is sensed through the detection of returns in a short water column adjacent the hull. In a further embodiment, returns from the water column coupled with receiver gain being open above a predetermined threshold provide the indication of the presence of the unsuitable water condition. The subject system may be used for other unsuitable water conditions that exist at the hull of the vessel and which would cause erratic depth readings, with such unsuitable water conditions including non-laminar flow, oil or sludge, and turbulence or bubbles, all of which result in returns in the water column immediately beneath the hull.
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