ECDIS Flashcards
SQA NAV theories (20 cards)
the function and presentation of the ECDIS ‘Safety Contour’ setting to assist in the transit
The safety contour is an outline which marks the division between safe and unsafe waters.
The colour blue is used to indicate the unsafe areas while white or grey for safe areas.
The default safety contour if not specified by the mariner is set to 30m.
ECDIS allows the officer to set safety parameters according to the ship’s static or dynamic particulars
the function and presentation of the ECDIS ‘Safety Depth’ setting to assist in the transit
The safety depth shows spot soundings either in gray for deeper depths or black for shallower depths
compared to the safety depth value entered by the navigating officer thereby highlighting the potentially
safe and unsafe areas
with regards to ENC reliability, State the Datum(s) used for Depth
Chart Datum
with regards to ENC reliability, State the Datum(s) used for Heights, relating to Drying Heights,
Chart Datum
with regards to ENC reliability, State the Datum(s) used for Vertical Clearance and other Elevations
Heights of shore objects are given above MHWS in areas where the Tides are Semi-Diurnal and MHHW
where there is a Diurnal Inequality. Mean Sea Level (MSL) is used where there is negligible Tide
with regards to ENC reliability, State the Datum(s) used for Positions
WGS-84
Define SCAMIN (Scale Minimum Value) of an object on an Electronic Navigational Chart
The “SCAMIN” value of an object determines the display scale below which the object is no longer visible
on an ECDIS.
The purpose of SCAMIN is to:
reduce the amount of clutter displayed to the ECDIS user,
to prioritize the display of objects and
to improve display speed
Outline the Survey Source Data and how the six ‘Category of Zone of Confidence’ (CATZOG) data is
presented on Electronic Navigational Charts.
SEE CARD 9-15
What do CATZOC values indicate?
The accuracy of data presented on charts to assist mariners with determining a safe Under Keel Clearance (UKC)
CATZOC stands for Category Zone of Confidence
What is the definition of ZOC Category A1?
Full area search undertaken with significant seafloor features detected and depths measured; high position and depth accuracy using DGPS and a multi-beam, channel or mechanical sweep system
DGPS stands for Differential Global Positioning System
What characterizes ZOC Category A2?
Full area search undertaken with significant seafloor features detected; position and depth accuracy less than ZOC A1 using a modern survey echo-sounder and a sonar or mechanical sweep system
How is ZOC Category B defined?
Full area search not achieved; uncharted features hazardous to surface navigation are not expected but may exist; controlled survey with similar depth but lesser position accuracies than ZOC A2
No sonar or mechanical sweep system is used in this category
What does ZOC Category C imply?
Full area search not achieved; depth anomalies may be expected; low accuracy survey or data collected on an opportunity basis such as soundings on passage
What is the meaning of ZOC Category D?
Worse than ZOC C; full area search not achieved; large depth anomalies may be expected; poor quality data or data that cannot be quality assessed due to lack of information
What does the ‘U’ category signify in ZOC?
Unassessed; the quality of the bathymetric data has yet to be assessed
Explain the difference between safety depth setting and safety contour display setting on an
ECDIS, whilst also outlining the importance of understanding this difference to a mariner for the
purpose of safe navigation
Safety Depth
Set by the user.
ECDIS emphasizes soundings equal to or less than the safety depth whenever selected for display. Affects the display of sounding colors
Soundings shallower appear in black
Soundings deeper appear in grey
Safety Contour
The primary safety feature in ECDIS.
Equivalent to a No Go line.
Set by the user to mark the boundary between safe and unsafe water
Shown emphasised over all other contours
Uses the next deepest contour (or boundary of depth area) in the chart
The chart display logic assumes that the safety contour will never be crossed.
Dangers on the shallow side may not be shown.
Name the corresponding mode that the equipment is operating in and outline the degree to which each mode fulfils the ECDIS functional requirements for the need to carry nautical charts on board:
(i) Approved ECDIS equipment operating with ENCs
ECDIS Mode.
Nautical charts need not be carried provided there is adequate backup, duplicate
equipment.
Name the corresponding mode that the equipment is operating in and outline the degree to which each mode fulfils the ECDIS functional requirements for the need to carry nautical charts on board: Approved ECDIS equipment operating with unapproved Vector charts
? Mode.
An appropriate folio of current paper charts is required to be carried
Name the corresponding mode that the equipment is operating in and outline the degree to which each mode fulfils the ECDIS functional requirements for the need to carry nautical charts on board:
Approved ECDIS equipment operating with RNCs
RCDS Mode. An appropriate folio of current paper charts is required to be carried
Outline the operational limitations of ECDIS equipment operating with RNCs when compared to
ECDIS equipment operating with ENCs
RNCs cannot:
be interrogated,
provide alarms,
provide indications,
provide customized display,
Display may be cluttered with additional information
