CATZOC ll Category of Zone of Confidence ll ENC ll ECDIS ll UKC ll Passage Planning ll Navigation

How to calculate UKC? • How to Calculate Under...
This video explains CATZOC (Category of Zone of Confidence). It shows how to determine the zone of confidence value to find the actual depth of the water from the stated charted depth in the ENC. It also shows how to activate the layer of accuracy using a JRC ECDIS.
CATZOC stands for Category of Zone of Confidence. It describes the level of confidence or accuracy of hydrographic survey data used in nautical charts. It refers to the quality and accuracy of survey data and the applicable error in the chart datum.
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[@babinbabi7545]

Can you please explain zoc for D / U

[@nauticalacademy001]

ZOC D represents areas where the survey data is of low reliability. It indicates significant limitations in the accuracy and completeness of the hydrographic information.
Here are the details for ZOC D:
Position Accuracy: Worse than ±500 meters. This means that the actual position of features on the chart can deviate by more than 500 meters from their charted location.
Depth Accuracy: Worse than ±2.0 meters + 5% of depth. The depth information is less reliable, with potential errors of more than 2 meters plus an additional 5% of the depth value.
Seafloor Coverage: Depths may not be fully surveyed, and there is a high likelihood of uncharted features. The survey may have been conducted using older or less comprehensive methods, such as lead line soundings or incomplete single-beam echo soundings.
Hazard Implications: Navigating in ZOC D areas carries a significant risk. Mariners must exercise extreme caution, as uncharted underwater hazards or features may exist. It's advisable to avoid these areas if possible or navigate at reduced speeds to allow for safe maneuvering if an uncharted hazard is encountered.
ZOC U signifies areas where the quality of the hydrographic data has not been assessed. This category is used when there is no information available about the accuracy or reliability of the survey data.
Here are the details for ZOC U:
Position Accuracy: Unknown. There is no information about the positional accuracy of the features on the chart.
Depth Accuracy: Unknown. There is no information about the accuracy of the depth measurements.
Seafloor Coverage: The quality of the bathymetric data is not assessed. This means there is no guarantee of the accuracy or completeness of the seafloor information. Surveys may have been conducted long ago, using outdated methods, or data may be entirely lacking.
Hazard Implications: Navigating in ZOC U areas is highly risky. Mariners should assume the worst-case scenario regarding uncharted hazards and lack of accurate depth information. Extreme caution is necessary, and these areas should be avoided if possible.
When navigating through areas marked as ZOC D or ZOC U:
Exercise Caution: If possible, reduce speed and maintain a vigilant lookout. Be prepared for unexpected hazards.
Use Additional Navigation Methods: Supplement chart information with other navigation aids such as radar, echo sounders, and visual references.
Plan Alternate Routes: If possible, plan routes that avoid ZOC D and ZOC U areas, especially in poor visibility or adverse weather conditions.
Consult Local Knowledge: If available, use local pilot guides, notices to mariners, and advice from experienced local mariners to gather additional information about the area.
Safety Margins: Increase safety margins by navigating further away from potential hazards and allowing more space for error in position and depth.