Sperry Marine Visionmaster FT ECDIS User Manual page 273

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Drop Bearing Object
A Drop Bearing object (DBO) is an object that can be observed at a
planned bearing when ownship is correctly positioned to drop anchor.
A DBO can be manually selected by specifying its L/L coordinates, or by
clicking the On Chart button, positioning the cursor over the object and left
clicking. If no chart object is identified after a query, the selected cursor
position is used to calculate the drop bearing value.
If enabled in the Display options, the display shows an outline circle with
the letters DB inside to visually indicate the current DBO position.
The bearing value from the CCRP to the DBO is continuously updated on
the Status tab.
Drop Range Object
A Drop Range object (DRO) is an object that can be observed at a planned
range when ownship is correctly positioned to drop the anchor.
A DRO can be manually selected by specifying its L/L coordinates, or by
clicking the On Chart button, positioning the cursor over the object and left
clicking. If no chart object is identified after a query, the selected cursor
position is used to calculate the drop range value.
If enabled in the Display options, the display shows an outline circle with
the letters DRg inside to visually indicate the current DRO position.
The range value from the CCRP to the DRO is continuously updated on the
Status tab.
Watch Settings
The Watch Settings area allows the operator to enter values for anchor
depth and chain scope, which are used by the system to calculate the
values for chain length, drag circle radius and swing circle radius. These
values are used to generate an alert if an anchor drag is detected.
A Warning will be raised if any part of the outline moves outside the swing
ring. If the Warning is not acknowledged within 2 minutes and own ship
remains outside the swing ring, the Warning is escalated to Alarm status
and the anchor symbol will change colour to red. If the anchor watch
function is deactivated while this alert is present, the alert shall be cleared.
The figure below shows a diagram of the Anchor Settings parameters.
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