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Safety at Sea • Electronic Charts The Ultimate Life Saver Datrex's DECKBUOY,® BRIDGEBUOY® High impact linear low density orange polyethylene (hard shell) Superior life expectancy in severe environmetal extremes. DECKBUOY: 30" 2.5 kg. buoy with retroreflective tape. Approved for shipboard and offshore deck platform installations. Meets U.S.C.G. and S.O.L.A.S. EC Certified BRIDGEBUOY: 30" 4 kg. buoy with retroreflective tape. Approved for use with quick release ring buoy bracket Meets U.S.C.G. and S.O.LA.S and EC Certified. NEW 24' DIAMETER NOW AVAILABLE U.S.C.G. APPROVED ISO 9002 Certified P.O. Box 1150, Kinder, LA 70648 P0-828-1131 Fax: 318-738-5675 latrex.com Charting The World Electronically The advent of electronic chart technolo- gy has left ship and boat owners with an unprecedented tool to aid in safe and effi- cient navigation. But while the electron- ic advances have swept interest and head- lines around the world, they have also cre- ated a considerable amount of confusion regarding, for example, when electronic charts can legally replace paper versions. With the notion of clearing the air, MR/EN has spoken with one of the world's leading companies in the field, C- Map, to discuss the ins and outs of new electronic chart technology. Currently, ship owners are focusing on the availability of quality electronic chart data for ECDIS. C-Map, being the largest supplier of charts in digital format, has responded to the requirements by offering worldwide coverage on CD ROM. The data from C-Map is coded in proprietary System Electronic Navigational Chart (SENC), optimized for direct use by the onboard ECDIS computer. This format, dubbed CM93 by C-Map, has been adopt- ed by many manufacturers of ECDIS sys- tems (Please see Table l). ENC & ECDIS It is imperative to note that only Nation- al Hydrographic Offices (HOs) can issue Electronic Navigation Charts (ENC) data as a paper chart replacement. HOs can, and do. subcontract work to commercial companies, but the HO is ultimately responsible for data quality control. Only when ENCs are displayed on a type- approved ECDIS system can they replace paper charts. The International Hydrographic Organi- zation (IHO) has defined the ENC chart format specified in the S-57 Edition 3 (S- Circle 226 on Reader Service Card 44 Table 1 ECDIS and ECS Manufacturers that have selected C-Map CM93 Cartography for their ECDIS Company For more information Circle Advanced Marine Technology 121 Coastal Oceanographies 122 Corp Ten lntl 123 EDO Corp 124 Electronic Design Inc 125 Kongsberg Simrad 126 Leica 127 Litton Sperrv Marine 128 Lockheed Martin 129 NetSea Inc 130 Northrop Grumman 131 Q-Mar 132 Quality Positioning Services 133 Racal Pelagos Inc 134 Raytheon Marine 135 Ship Analytics 136 57/3) product specification, which is a detailed format developed as a data exchange format to be used by HOs. It is not a format designed to be manipulated and displayed on a navigation screen, and for this reason the ECDIS Performance Standards accept that ENC data is com- piled into an internal format in the ECDIS system, or in a SENC format. Thus, one of the more critical steps is ensuring the integrity of the data when compiling from ENC to SENC format. The presentation of nautical charts and symbols on a navi- gation system is defined by the IHO as well, in the S52 specification, which is also referred to in the ECDIS Perfor- mance Standards. Partnerships C-Map, in effect, acts as a link between the HOs and the users of digital nautical charts, and the company is constantly developing new technology and services to achieve this goal. C-Map is not only working with HOs to digitize paper charts, but working with them also to develop their national ENC portfolios in S-57/3. C-Map developed the CM-93 Edition 3 (CM-93/3) format that fully complies with the S-57/3 format as defined by the IHO. Data produced by C-Map is produced in CM-93/3 format, which is used by a num- ber of system manufacturers as their SENC format. C-Map has developed soft- ware that compiles S-57/3 data in CM- 93/3 format. The compiler was type- approved by DNV, to ensure that there is no loss or corruption of data in this process. This compiler is suppled to sys- tem manufacturers that use CM-93/3 as a SENC to enable their systems to read S- 57/3 data directly. The CM-93/2 chart portfolio of 13,900 chart files produced by C-Map has been converted into the same CM-93/3 SENC format, but it can only be used as an aid to navigation. ECDIS systems that use CM- 93/3 have access to extensive chart cover- age. As ENC data becomes available, this will take priority over other data and be clearly recognized as official data when displayed, but unfortunately only limited ENC data is presently available. Distributing charts in the SENC format means that the updating of charts can be carried out via the Internet, or remote access using a shipboard communications line. The SENC format, in effect, is a compressed format (approx. 1:5) in com- parison to S-57/3, and additionally, no compression is required onboard. Circle 137 on Reader Service Card
