ECDIS

For centuries, seafarers have relied on paper charts for safe navigation. With advances in technology, and knowledge of the sea, the Electronic Chart Display and Information System, or ECDIS, is the new navigational standard. ECDIS is an alternative to paper charts that complies with International Maritime Organization regulations. In this program, we will learn the basics of ECDIS, including chart systems, regulatory requirements, watchkeeping and alarms, dangers of ECDIS, and passage planning. There are two types of electronic charts, Raster Navigation Charts, also called RNCs, and Electronic Navigation Charts, called ENCs. RNCs are images of existing paper charts and contain only visual and positioning information. ENCs, also called vector charts, contain much more data than Raster or paper charts. ENCs can be scaled, rotated, and queried as needed with the ability to enable or disable layers of information to declutter or augment the display. ECDIS is a valuable resource for crew working on the bridge. One screen may combine the display inputs from the GPS, gyrocompass, ARPA, and even more. ECDIS integrates data from navigational equipment with the electronic chart to form the SENC, or System Electronic Navigation Chart. This data is then displayed at the ECDIS terminal. All of this information can help improve situational awareness on the bridge and make passage planning more effective and efficient. This is why the fitting of ECDIS aboard most ships now is mandatory. In 2009, the International Maritime Organization amended SOLAS chapter five regulation 19 to require most ships engaged on international voyages to be fitted with ECDIS, according the following timetable. SOLAS also requires that ECDIS is backed up, either with a folio of paper charts, or with a redundant ECDIS system. To meet SOLAS requirements and ensure accurate charting information, the ECDIS system must be updated weekly. Depending on the distributor, chart up dates will be installed via DVD or download. Both the primary and backup ECDIS must be updated. To meet IMO requirements, every officer of the watch assigned to a ship using mandatory ECDIS, or any vessel using ECDIS for primary navigation, must undergo IMO Model Course 1.27 training. The type training may be provided by a trained ship's officer and documented. A tremendous advantage of ECDIS over paper or Raster charts is the variety of settings and alarms to help keep watchkeepers better informed. Another benefit is that all navigational information can be overlaid on the display for comparison and verification. As with paper charts, it is vital that the navigator chose the correct chart scale for the task at hand. Navigating coastal waters with ECDIS set to scale for oceanic transit can be extremely dangerous as some navigational hazards may not be visible. The watch vector is perhaps the most important ECDIS setting. The watch vector is also known as the anti-grounding cone, or look ahead setting and is based upon the stopping distance and turning radius of the vessel. The watch vector defines the area in which ECDIS will alarm, should the vessel approach a navigational hazard. Without this setting, the ECDIS will provide no advance warning. Additionally, watchkeepers should verify the safety contour and spot depth settings on the ECDIS. The broadest depth setting is the safety contour depth which provides a visible boundary between safe and unsafe water. The safety contour depth is set by the navigator to reflect the vessel's safety draft, which is commonly calculated at the vessel draft plus dynamic squat, plus the safety margin. ECDIS displays soundings as well as depth contours. Safe soundings are indicated by the safety depth. In most situations, the safety depth and safety contour depth will be the same. Safety depths should never be less than the safety contour. Navigators may choose to display depth contours in two or four colors. It's most important that navigators verify their understanding of the chart display as settings like night mode may lead to confusion. Additional depth information can be displayed by the shallow and deep contours settings. Most importantly, Raster charts can not be read by the ECDIS. Vector data is necessary for navigational alarms. If functioning in Raster Chart Display System, or RCDS mode, the terminal will not warn of navigational hazards. ECDIS can be very useful for passage planning. Some of the features include graphical way-points, track data for the autopilot, voyage schedule calculation, and safety checks. Passage planning on the ECDIS system begins with either selecting a pre-created route or creating a new graphical passage plan by plotting the way-points. If part of the passage is not covered by ENC charts, mariners may use the ECDIS terminal in RCDS mode. In this configuration, the ship must have up-to-date paper charts as backup, and most alarms will not function in this mode. Once the route is established, the navigator uses the automatic check function of ECDIS to asses the track and identify any hazards. It is imperative that the safety contour, watch vector, and cross track deviation are set correctly. After the navigator has adjusted the track and addressed any alarms, it's then approved by the master and loaded for use throughout the voyage. ECDIS is only as safe a tool as the navigators who use it. Overreliance on ECDIS can lead to dangerous lapses in situational awareness. Careful planning, cross checking, and a vigilant watch are still the keys to the safety of the ship and all aboard. Just one of the many accidents blamed on the misuse of ECDIS, the grounding of the chemical tanker Ovit in the Dover Strait was a close call to disaster. Investigations revealed that the master had delegated passage planning to the third officer, who had little prior experience. The third officer planned the track on ECDIS and checked the track visually. The third officer did not realize that this planned course ran directly across The Varne Bank, a dangerously shallow hazard and part of a traffic separation scheme. When the master checked the course, he disregarded the numerous alarms generated by the automatic route check. While navigating the Dover Strait, the master set the map scale to 1:350.000 when a scale of 1:45.000 would have been appropriate for channel navigation. Visual ECDIS depth contour, cross track deviation, and map scale alarms were all ignored and the audible ECDIS alarm was never configured. ECDIS aside, buoys marking the east and west sides of The Varne Bank were visible at five nautical miles, but not reported by the watch. The master was unaware that the ship was aground until a call from the Coast Guard prompted him to look closer at the ECDIS. Any ECDIS alarm should be fully investigated by the officer of the watch. In the case of the Ovit, a simple look out the bridge window could have prevented the grounding. Fortunately, the crew avoided injury and the vessel sustained minimal damage. ECDIS is required to save track and instrument data in a log for at least the previous 12 hours and may save these records indefinitely. Location data is recorded in four hour or shorter increments across the entire voyage. The crew should know how to preserve ECDIS data in case of a marine accident and investigation. Ultimately, ECDIS is a powerful addition to bridge operations. The success or failure of ECDIS depends on you, the mariner, to be informed and vigilant. In this introduction to ECDIS, we learned about the critical importance of chart scaling, IMO requirements for the use of ECDIS, learning how to set safety contours, depth, and watch alarms, understanding the dangers of ECDIS, including overreliance and position errors, and passage planning, including route safety checks. Mastery of ECDIS allows the observer improved awareness, preventing navigational errors and maritime causalities. With this elegant solution at hand, you can always stand your watch with confidence.