It is for each national hydrographic office to produce ENCs of its territory but not that of its neighbours even though in some cases this may mean that the display on the ECDIS may be missing features in parts. The problems that could arise because of this and which could impact on the safety of ECDIS were recognised by the IHO which responded by establishing the Worldwide Electronic Navigational Chart Database. WEND covers the standards to which charts must be produced and principles of co-operation between hydrographic offices and establishes the concept of a network of Regional Electronic Chart Coordinating Centres (RENCs) that allows members of the IHO to cooperate to resolve overlaps and gaps in coverage. Each RENC takes over the responsibility in its area for the collation of ENCs and up dates for the region and through the exchange of the regional datasets and their updates between all RENCs each RENC can offer an identical global dataset for ECDIS. It was not intended for the RENCs to become distributors of ENCs to vessels. That role was left for commercial organisations to apply to become value added retailers (VARs) and to develop their own distribution channels in much the same way as Inmarsat services are delivered by service providers. The WEND concept has not been fully adopted by all ENC producing nations and some still insist on distributing their ENCs individually either through chart data suppliers or directly. There are currently two RENCs in existence, Primar and IC-ENC. Primar headquartered in Norway includes the national hydrographic offices in Brazil, Croatia, Denmark, Estonia, Finland, France, Greece, Iran, Latvia, Mozambique, Norway, Poland, Russia and Sweden. IC-ENC has offices in the UK and Australia and its membership comprises Argentina, Australia, Bahrain, Belgium, Brazil, Chile, Colombia, Cuba, Denmark, Ecuador, Germany, Greece, Iceland, Mexico, Mozambique, Netherlands, New Zealand, Pakistan, Peru, Portugal, Romania, Russia, South Africa, Spain, Turkey, United Kingdom, Uruguay and Venezuela. When an ECDIS is supplied by the manufacturer some will be delivered with a complete world folio of ENCs, some will come preloaded with ENCs agreed between buyer and seller and some will be devoid of ENCs altogether. It remains the owner’s responsibility to ensure that ENCs for the voyages a ship is undertaking are both licenced for use and up to date. If the ECDIS has no or insufficient ENCs installed, the owner must obtain them from an authorised distributor appointed by a RENC or national hydrographic office as appropriate. Being only data, an ENC can be delivered by any method of direct transfer (CD, DVD, USB etc) the ECDIS supports or via broadcast download using the ship’s communication system. Martek Marine’s iECDIS also has an additional option of updating using the GSM networks by way of an integrated modem. There are distributors all over the globe just as there always have been for paper charts but the very different method of using ENCs has led to a small number of specialist distributors appearing. All distributors can deliver ENCs in S57or S63 format for the ECDIS to convert into SENC but some of the major companies will have a proprietary SENC format that certain ECDIS makers have integrated into their systems. Where an ECDIS maker has preloaded the system with a full or partial folio, the licences still need to be obtained from a distributor. Even when the only charts available were paper charts, SOLAS required ships to have up to date official charts on board for their intended voyage. That requirement has not altered with the advent of ECDIS but it does now apply to both paper and electronic charts. Ships that can go paperless because they have a dual ECDIS on board and the sanction of the flag state to dispense with paper charts need only have the appropriate licensed and updated ENCs on board. For vessels with just a single ECDIS or where the flag state does not permit paperless navigation, both paper and ENCs need to be maintained up to date. Paper charts are updated manually by way of tracings supplied by chart agents and using information contained in Notice to Mariners (NTM) which are distributed by various flag states and which can be obtained by subscription or by collection from customs and port authority offices. Most port agents maintain a collection of NTMs which they make available to ships consigned to them. With the advent of satellite communications it has become possible to distribute NTMs using broadcast services and e-mail. ENC updating is a far easier task only involving running the update data which can be provided by CD/DVD, e-mail or broadband. Some ECDIS and some chart providers’ software can recognise which ENCs need updating and perform the update automatically whereas others require intervention from the ECDIS user. It is important when updates are done by ECDIS users to log which updates have been applied. If a user forgets to update an ENC, it will still display but obviously without the update. This could prove dangerous and could result in a PSC detention. In this respect ENCs are no different from paper charts. As explained in Chapter 2, some advanced ECDIS have additional features such as weather, tidal and even information on latest pirate activity that can be overlaid on the ENC display. These services also rely on broadcast information and often use the same software that manages chart updates to ensure the latest information from these services is being displayed. If and when S-100 ENCs become standard the number and type of additional overlays is likely to increase and there is the possibility that some could even update in real time. The Admiralty Information Overlay, a free service to Admiralty Vector Chart Service customers is claimed as the only service available to include worldwide Admiralty Temporary and Preliminary Notices to Mariners and new ENC Preliminary Notices to Mariners, which identify navigationally significant differences between ENCs and Admiralty paper charts.