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Архитектура Аудит Военная наука Иностранные языки Медицина Металлургия Метрология Образование Политология Производство Психология Стандартизация Технологии |
Configuring the ECDIS to cross the safety contour: Method 2
In this method, the safety depth is calculated and entered as above, but the safety contour is set to the next shallower contour. If the ECDIS supports manual generation of contours, the Deck Officer draws a manual safety contour at the actual depth required, using the highlighted depths as guidance. The manual contour should be drawn in a similar manner to a "no go line or area" on a paper chart or RNC.
To do this safely, care will be needed to ensure that suitable display settings are enabled so that all possible dangers are shown. Where possible, the manual contour should be set as a user "alarm" Line or avoidance zone, such that during an electronic route check or monitoring it will cause a safety alarm to be activated. The exact method for doing this on the ECDIS in use may vary, as will the exact terminology used for these user-defined features.
This method avoids the need to ever cross the safety contour (relying on a user defined contour for alarm generation). and should prevent the potential complacency problems described in method I above.
However, it does pose other potential hazards: I. A hazard could be missed during the visual inspection of the ENC and the manual drawing process, with no electronic warnings or alarms to warn the user, as the safety contour is not set. Checking should confirm that the manual line has been set as an alarm feature. 2. Isolated dangers in safe water may not be highlighted if a safety contour value is not set (because the configured safety contour is artificially shallow). These will have to be manually highlighted as manual updates using the ECDIS' Display "ALL" category.
Both of these methods have inherent dangers and should only be used where necessary. The potential consequences of carrying out either method incorrectly or with a poor understanding of the care needed should be made clear in the final procedure adopted. Care should also be taken to require that each individual occasion is separately authorised by the Master and is recorded in accordance with the SMS.
It may also be prudent to specify that, whichever method is used, the manual drawing is checked by another officer who is not otherwise involved in that part of planning process, to prevent an error by one person causing a major incident.
Example procedure Procedure for crossing the safety contour: Method 2: a) Calculate Safety Depths and enter into ECDIS b) Select viewing groups for soundings. seabed features and contours to be displayed. c) Construct a manual update line to create a safety contour equivalent to the safety depth, using the highlighted safety depth as an indication of the contour- allow a safety margin where values displayed are less than the safety depth. Use existing contours to establish the likely shape of the manual contour d) Set the manual update line as an alarmed feature (refer to ECDIS manual and training course notes for guidance) e) Run the route check facility to confirm that the feature will alarm f) Ensure the plan is clear when the safety contour should be set to the artificial value and reset once the area is clear g) Save as part of the Voyage Plan in ECDIS and note the feature in the Voyage Plan notes for review and approval by the Master
1.12 Zo nes of Confidence (ZOC) Table (CATZOC)
Depth Accuracy 3 | S eafloor Coverage |
T y pical Survey Characteristics 5 | ||||||||
| ± 5 m + 5% | =0.50 + 1%d | Full area search undertaken. Significant seafloor features detected 4 and depths measured.
| Controlled, systematic survey 6 high position and depth accuracy achieved using DGPS or a minimum three high quality lines of position (LOP) and a multi-beam, channel or mechanical sweep system.
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| Depth (m) | Accuracy (m) | |||||||||
| A1 | depth | 10 30 100 1000 | ± 0.6 ± 0.8 ± 1.5 ± 10.5 | |||||||
| ± 20 m | = 1.00 + 2%d | Full area search undertaken. Significant seafloor features Detected 4 and depths measured | Controlled, systematic survey 6 achieving position and depth accuracy less than ZOC A1 and using a modern survey echo-sounder 7 and a sonar or mechanical sweep system. | |||||||
| Depth (m) | Accuracy (m) | |||||||||
| A2 | 10 30 100 1000 | ± 1.2 ± 1.6 ± 3.0 ± 21.0 | ||||||||
| = 1.00 + 2%d | Full area search not achieved; uncharted features, hazardous to surface navigation are not expected but may exist. | Controlled, systematic survey achieving similar depth but lesser position accuracies than ZOC A2, using a modern survey echo-sounder 5, but no sonar or mechanical sweep system. | ||||||||
| Depth (m) | Accuracy (m) | |||||||||
| B | ± 50 m | 10 30 100 1000 | ± 1.2 ± 1.6 ± 3.0 ± 21.0 | |||||||
| = 2.00 + 5%d | 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. | ||||||||
| Depth (m) | Accuracy (m) | |||||||||
| C | ± 500 m | 10 30 100 1000 | ± 2.5 ± 3.5 ± 7.0 ± 52.0 | |||||||
| D | W o rse than ZOC C |
Worse than ZOC C | Full search not achieved, large depth anomalies expected. | Poor quality data or data that cannot be quality assessed due to lack of information. | ||||||
| U | Unassessed - The quality of the bathymetric data has yet to be assessed |
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Explanatory notes quoted in the table:
1. The allocation of a ZOC indicates that particular data meets minimum criteria for position and depth accuracy and seafloor coverage defined in this Table. ZOC categories reflect a charting standard and not just a hydrographic survey standard. Depth and position accuracies specified for each ZOC category refer to the errors of the final depicted soundings and include not only survey errors but also other errors introduced in the chart production process. [Note: the rest of footnote I does not apply to paper charts and is therefore omitted from S-4].
2. Position Accuracy of depicted soundings at 95% Cl (2.45 sigma) with respect to the given datum. It is the cumulative error and includes survey, transformation and digitizing errors etc. Position accuracy need not be rigorously computed for ZOCs B, C and D but may be estimated based on type of equipment, calibration regime, historical accuracy etc.
3. Depth accuracy of depicted soundings= a+ (bxd)/ I 00 at 95% Cl (2.00 sigma), where d =depth in meters at the critical depth. Depth accuracy need not be rigorously computed for ZOCs B, C and D but may be estimated based on type of equipment, calibration regime, historical accuracy etc.
4. Significant seafloor features are defined as those rising above depicted depths by more than: Depth Significant Feature a. <40m2 m b. >40 m I 0% depth A full sea floor search indicates that a systematic survey was conducted using detection systems, depth measurement systems, procedures, and trained personnel designed to detect and measure depths on significant seafloor features. Significant features are included on the chart as scale allows. It is impossible to guarantee that no significant feature could remain undetected, and significant features may have become present in the area since the time of the survey.
5. Typical Survey Characteristics- These descriptions should be seen as indicative examples only.
6. Controlled, systematic surveys (ZOC A I, A2 and B) - surveys comprising planned survey lines, on a geodetic datum that can be transformed to WGS 84.
7. Modern survey echo-sounder -a high precision single beam depth measuring equipment, generally including all survey echo-sounders designed post 1970.
ECDIS failure
Refer to the Ship Emergency Response Manual for ECDIS related contingencies also refer to Appendix 8 for Ship specific contingency plans
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