Thomas Gunn Navigation Services Ltd have been supplying electronic charts for approximately 10 years. In recent years the number of users of electronic charts has grown significantly and electronic charts are now used in a variety of applications including: sailing, diving support, fishing, survey work, research studies, rig moves and commercial shipping.
 

The growing interest in electronic charts is largely due to the advantages the electronic chart offers in comparison to the traditional paper chart. A brief list of benefits is detailed below:

• Improved situational awareness
• Quick and accurate application of chart correction information
• Ability to add charts to the system remotely
• Reduced requirement for storage space
• Ability to overlay user information and manipulate screen shots of the data.

Our range of electronic charts includes the following:


IT IS IMPORTANT TO NOTE THAT ALL OF THE FOLLOWING CHART SYSTEMS REQUIRE THE ADDITIONAL PURCHASE OF COMPATIBLE ELECTRONIC CHARTING SOFTWARE TO UTILISE THE CHART DATA.

Guide to Electronic Charting
At Thomas Gunn Navigation Services Ltd we receive a large number of enquiries relating to the most appropriate type of electronic charts for a given application. In order to assist in the complicated process of selecting electronic charts we have devised the TGNS Guide to Electronic Charting.
 

Arcs Skipper (Leisure)
Arcs service operated by the United Kingdom Hydrographic Office and aimed at the leisure user who demand a high quality chart (based on official data) but may not require access to the latest correction information. This service offers Arcs charts which are fully corrected up to the date of purchase and can be optionally updated via subscription to an annual or quarterly update service. Please note the user owns the charts and the system will allow indefinite access to the chart data.


A minimum of 10 charts must be purchased for the initial order - charts can be purchased individually, via pre-selected folios or customised folios tailored to your exact requirements.
 

Arcs Navigator (Commercial)
Arcs service operated by the United Kingdom Hydrographic Office and aimed at the commercial user who demands a high quality chart (based on official data) which incorporates the latest safety critical correction information. The Navigator service is a subscription based service and access to the charts are provided for a 12 month period, on expiry of the subscription period access to the chart data is lost. The advantage of the Navigator service is that the charts are maintained and corrected via the supply of a weekly update CD for the duration of the subscription.


A minimum order value of £500 is enforced by the UKHO and this equates to a folio of approximately 32 charts. Several discount structures are in place to ensure large quantities of individual charts or folios are competitively priced.
 

C-Map
C-Map are a well respected private company who produce electronic vector charts for a number of applications i.e. the C-Map NT charts for leisure plotters and the CM93 database for commercial shipping users.


Individual chart purchases are not possible through C-Map but geographic cells, folios and zones are available which offer complete coverage of the selected area.


The main advantage of a vector chart is that the data, which comprises the chart, can be interrogated when coupled with a suitable piece of software. In addition the chart inventory can be zoomed to a greater degree than a raster based chart such as Arcs.
 

Official Electronic Navigational Charts (ENC’s)
These are vector charts (similar to those produced by C-Map) produced by national hydrographic offices and based upon official survey data.


Official ENC’s were introduced approximately three years ago and are still a relatively new development within the electronic chart world. As a result worldwide coverage is not currently available, however the coverage is growing at a steady rate.


Official ENC’s are suited to a range of applications but are largely designed for commercial users. The use of ENC’s can in special circumstances lead to a reduction in the number of paper charts which are carried and maintained onboard a SOLAS registered vessel.
 

Rules and Regulations
The use of ENC and the possible reduction of paper chart inventories onboard depends on a large number of factors including available coverage, use of an approved ECDIS system, appropriate backup measures being in place and adherence to the appropriate legislation governing the use of ECDIS.


The legislation issues may be the largest single factor holding back the adoption of ECDIS. At TGNS we have collated a number of documents to assist in the understanding of the appropriate rules and regulations.