Page 44: of Maritime Reporter Magazine (April 2000)

Safety at Sea • Electronic Charts

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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-

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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