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Passage planning and electronic navigation systems

2.3.4.1 Planning using electronic chart display systems

Passage planning can be undertaken either on paper charts or using an electronic chart display and information system (ECDIS) displaying electronic navigational charts (ENC), subject to the approval of the flag state administration. Raster chart display systems (RCDS) displaying raster navigational charts (RNC) can be used for passage planning in conjunction with paper charts (see section 4.9).

When passage planning using ECDIS, the navigating officer should be aware that a safety contour can be established around the ship. The crossing of a safety contour, by attempting to enter water which is too shallow or attempting to cross the boundary of a prohibited or specially defined area such as a traffic separation zone, will be automatically indicated by the ECDIS while the route is both being planned and executed.

When passage planning using a combination of electronic and paper charts, particular care needs to be taken at transition points between areas of electronic and paper chart coverage. The voyage involves distinct pilotage, coastal and ocean water phases. Planning within any one phase of the voyage should be undertaken using either all electronic or all paper charts rather than a mix of chart types.

Where a passage is planned using paper charts, care should be taken when transferring the details of the plan to an electronic chart display system. In particular, the navigating officer should ensure that:

• positions are transferred to, and are verified on, electronic charts of an
equivalent scale to that of the paper chart on which the position was
originally plotted;

• any known difference in chart datum between that used by the paper chart
and that used by the electronic chart display system is applied to the
transferred positions;

• the complete passage plan as displayed on the electronic chart display system
is checked for accuracy and completeness before it is used.

2.3.4.2 Transferring route plans to other navigation aids

Care must be taken when transferring route plans to electronic navigation aids such as GPS, since the ship's position that is computed by the navaid is likely to be in WGS84 datum. Route plans sent to the GPS for monitoring cross track errors must therefore be of the same datum.

Similarly in the case of radars, routes and maps displayed on the radar will be referenced to the position of the ship. Care must therefore be taken to ensure that maps and plans transferred to, or prepared on, the radar are created in the same datum as the navaid (typically a GPS) which is connected to, and transmitting positions to, the radar.


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2.4 Notes on passage planning in ocean waters

In open waters, the route selected will be either a great circle, composite great circle or rhumb line route.

When planning ocean passages, the following should be consulted:

• small scale ocean planning and routeing charts providing information on
ocean currents, winds, ice limits etc.;



• gnomonic projection ocean charts for plotting great circle routes;

• the load line zone chart to ensure that the Load Line (LL) Rules are complied
with;

• charts showing any relevant ships' routeing schemes.

Anticipated meteorological conditions may have an impact on the ocean route that is selected. For example:

• favourable ocean currents may offer improved overall passage speeds
offsetting any extra distance travelled;

• ice or poor visibility may limit northerly or southerly advance;

• the presence of seasonal tropical storm activity may call for certain waters to
be avoided and an allowance made for searoom.

Details of weather routeing services for ships are contained in lists of radio signals and in Volume D of the World Meteorological Organization (WMO) Publication No. 9. Long-range weather warnings are broadcast on the SafetyNET Service along with NAVAREA navigational warnings as part of the World-Wide Navigational Warning Service (WWNWS).

Landfall targets need to be considered and identified as to their likely radar and visual ranges and, in respect of lights, their rising and dipping ranges and arcs/colours of sectored lights.


Date: 2016-04-22; view: 1015


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