ANDY NORRIS MAIN HEAD Should raster be allowed? PHOTO REQUESTED DECK HEAD As the IMO prepares to debate once and for all whether raster chart display systems (RCDS) should be allowed for navigation where no official vector charts ("ENCs") have been produced, Dr Andy Norris explains the arguments on either side BODY A few months ago Australia submitted a proposal to the IMO Maritime Safety Committee (MSC) suggesting that a Work Programme be set up to consider whether ships should be able to use the Raster Chart Display System (RCDS) mode of ECDIS, without any requirement to carry paper charts on suitably fitted vessels. Although the use of RCDS had been covered by IMO in 1998 the Australian proposal arose from noting that the majority of ships fitted with ECDIS continued to carry a full folio of paper charts. Australia argues that this is due to the varied interpretation by port and flag states of the IMO requirements both for backup and for the condition that when in RCDS mode ECDIS equipment should be used together with an 'appropriate' folio of up-to-date paper charts. In Australia's view shipowners and operators are consequently delaying installing ECDIS as there is little incentive in so doing if they must continue to carry, maintain and use paper charts. Clearly, if the safety and environmental benefits of ECDIS are to be promptly realised then the rapid widespread adoption of ECDIS is needed. Australia considers that the objections that led to IMO's original (cautious) words on RCDS are now inappropriate because of experienced gained. Australia's arguments include: * The good zoom facilities now available on RCDS provide an adequate look-ahead and route planning capability. Since there are mandatorily displayed warnings over-zoom of RCDS data is not a problem. * The available update facilities on RCDS give a significant and immediate improvement in the maintenance of charts on board ships * There is no evidence that the use of the RCDS mode without the need to use appropriate paper charts has contributed to navigation incidents - it is more likely that reduced workloads and improved situational awareness has contributed to safer navigation * There will be a long time before there is full coverage of ENCs. Any fears that the use of RCDS will adversely impact the production of ENCs are groundless. The MSC meeting decided that this issue would be considered by the Navigation Subcommittee (NAV). NAV will complete these deliberations in the early summer of 2005. SUBHEAD RCDS sores The re-raising of the RCDS question has already opened-up unhealed sores among some members of the international hydrographic community. It is a shame because even at this late stage a more relaxed (and common view) of RCDS would lead to the increased fitting of ECDIS, just as Australia says, resulting in improved safety. The ECDIS performance standards were written before affordable computer technology could give a good rendition of an electronic chart. The problems that needed to be addressed by the standards included the poor resolutions of displays, the relatively slow processing times and the relatively limited memory in both hard disks and RAM. In particular, this made the use or raster charts more of a challenge. The limited screen resolution would make the symbology difficult to read unless the charts were shown at larger than 'real' size; the poor processing times and limited memory availability would create significant delays if the screen displayed area was changed by zooming, scrolling or stepping to a new area. With vector charts the symbology could be simplified to aid easy identification on a 'poor' resolution screen; only essential layers need to be displayed, reducing screen clutter and decreasing screen write times; and, importantly, despite what was showing on the screen, the look-ahead facility would be checking for dangers along the heading-line of the vessel. Together with other advantages of vector charts these were strong arguments supporting an ENC-only approach. By the time of the big RCDS debate that took place in 1998 many suppliers had shown that RCDS charts on the more modern computers and display technology then available could be clearly viewed and had rapid zooming and scrolling facilities, making near instantaneous look-ahead possible. SUBHEAD Anti-RCDS The debate about the pros and cons of RCDS spilled well outside the formal work of IMO. The 'public' debate was effectively won by the anti-RCDS protagonists on the following considerations, ignoring the advances in technology: * ENC vector charts are a superior technical option to RCDS (this is undisputed) * RCDS does not give automatic look-ahead warnings * IMO and IHO had already defined a minimum standard for electronic charts, how can an inferior standard now be acceptable? * If RCDS was given a freer use it would slow the production of ENCs Rarely voiced overtly was the biggest fear of the anti-RCDS lobby - if RCDS was given such a freer use then existing hydrographic offices with a global series of paper charts (and hence RCDS data) would extend their 'unfair' domination of the chart market into the electronic sector. In retrospect, had the decision in 1998 been effectively "the use RCDS mode is acceptable when ENCs are not available" it would have considerably boosted the carriage and use of electronic charts. Clearly, RCDS data suppliers would have initially benefited, albeit paying appropriate royalties to national hydrographic offices, but this would have undoubtedly resulted in increased activity on ENCs by national HOs so as to decrease the dominance of RCDS. Because this didn't happen the average ship has been denied the extra safety benefits of using electronic charts. ENCs are still being too slowly produced to allow paperless operation on most vessels. SUBHEAD So what should happen now? It should be straightforward. Unless anybody can come up with a substantiated argument that shows there would be a net decrease in safety and environmental protection then RCDS mode of operation should be allowed, without the additional need to use paper charts. This mode of operation should only be permitted in those areas where up-to-date ENCs are not publicly available or when it would have been unreasonable for the vessel to have expected that is would be entering an area where such ENCs were available. This would cover unexpected changes to voyages and the situation when relevant ENCs become available for the first time during a voyage. Allowing this would unlock the hiatus on fitting electronic charts use also increase the production rate of ENCs. Many ECDIS have a mode of operation that uses vector data from independent data suppliers (private data). There are good navigational reasons to use vector data and a number of vessels use private vector data, while maintaining formal use of paper charts. SUBHEAD RCDS and private vector together A good solution on a vessel fitted with dual ECDIS units, when in an area not covered by ENCs, would be to display RCDS on one display and private vector data on the other. If the RCDS rules were changed, as discussed, no paper charts would then need to be carried. Providing both ECDIS units were identical the same route plans, chart tools, etc would be used on each, reducing the workload. Proper use of this dual facility would highlight any data discrepancies between the systems, increasing safety. The benefits of using vector charts would be retained, complemented by the official status of RCDS data. Unofficial data does not comply with IMO chart carriage requirements and normally has clauses rejecting any liability for chart content. Without the need to carry paper charts this would perhaps be an affordable option for those preferring the features of vector chart systems.