電子海圖顯示及信息系統(tǒng)

電子海圖，一直強調(diào)它是一種用來加強安全的手段。在過去幾年提供給海事組織的多項調(diào)查顯示，這是預(yù)期的結(jié)果。但是，在實踐中，電子海圖是否會讓一些船舶駕駛員過于自信，甚至導致安全系數(shù)降低？

事實上，電子海圖系統(tǒng)的安全運行使得我們必須要開發(fā)一個新的用戶理念，比起使用紙質(zhì)海圖，電子海圖有許多截然不同的地方。一個好的理念應(yīng)該灌輸給用戶，作為電子海圖培訓的重要組成部分，而且不能過于強調(diào)通過死記硬背去學習任何一個特定的電子海圖操作，牢牢掌握基本原理才是最重要的。它不僅幫助灌輸正確的理念，還幫助用戶去熟悉不同船舶上不同的電子海圖的運用。

電子海圖的劣勢

在電子海圖這個理念當中，使用者應(yīng)該充分了解使用電子海圖基礎(chǔ)系統(tǒng)的優(yōu)缺點。讓我們從它的劣勢開始說起。最重要的是電子海圖是完全以電子為基礎(chǔ)的系統(tǒng)。電子化能導致系統(tǒng)的徹底癱瘓，又或者是形成操作的失誤。為了識別它的失誤，國際海事組織總是要求船舶要配備一套作為電子海圖的備用系統(tǒng)。雖然這可能只是一個紙質(zhì)海圖系統(tǒng)，但對于大多數(shù)的船舶來說這并不是一個明智的選擇，這是由于運作和財政方面的原因造成的。在一般情況下，最合適的后備方案就是再準備第二個電子海圖系統(tǒng)。用來避免眾所周知的復(fù)雜狀況，必須使備用電子海圖和主要的電子海圖保持一致。

有恰當使用電子海圖理念的用戶，應(yīng)該確保備用的電子海圖系統(tǒng)總是能有效地參與正在進行的航海過程，例如，能夠顯示出與主系統(tǒng)不同比例的視圖。為由此提高對周圍環(huán)境狀況的認知，定期地檢測一下備用的電子海圖，以確保當主要系統(tǒng)癱瘓的時候，這個系統(tǒng)可以備不時之需地成為主要系統(tǒng)。它也幫助識別出在任何一個系統(tǒng)中發(fā)生的故障。尤其特別的是，它同時還幫助確保那個備用系統(tǒng)正在正確加載運行目前的航線以及及時更新電子海圖。

標準電子海圖以及電子海圖顯示與信息系統(tǒng)設(shè)備的數(shù)據(jù)標準都是相當詳細的，這些數(shù)據(jù)標準是它們成為迄今為止最為復(fù)雜的船上系統(tǒng)。時不時會有一些未被預(yù)期的突發(fā)狀況發(fā)生。船舶駕駛員應(yīng)該一直清楚地了解到這些問題是存在的，并且同時知道解決這些問題的方法。這些解決方案可能包括一些臨時的措施。當然，公司詳細的安全管理體系都會全力支持船舶在這方面的需求。

一般而言，水道測量局可以根據(jù)編制的數(shù)據(jù)，很快解決那些由于電子海圖所引起的不正確的數(shù)據(jù)編碼。雖然這有時候也需要花費幾周的時間。由于各種各樣的原因，通常這些設(shè)備的異常問題需要滿意地解決，要花費制造商更長的時間，所以一般來說，升級電子海圖軟件是相當有必要的。使用者需要了解所使用設(shè)備的狀況，包括這個軟件所有沒有被解決的問題。不幸的是，許多航運公司沒有對航海設(shè)備的軟件進行升級，盡管遵從了國際海事組織的指導，比如在 2012年的 12月頒布的 MSC.1/ Cire.1389航海相關(guān)文件所指出的內(nèi)容。

然而，使用者很容易就會對于電子海圖的異常感到過度的焦慮。在實踐中，發(fā)生異常的相關(guān)數(shù)據(jù)真的很小，這些數(shù)據(jù)總是被見多識廣的使用者牢牢地印入腦海之中。如果有好的程序并且用戶也堅信這樣的程序確實存在，他們正確使用電子海圖，安全是不存在問題的，然而，如果電子海圖被無知地使用，那么他們將造成事故的發(fā)生。

顯示屏尺寸以及用戶界面

電子海圖最大的劣勢在于顯示屏的尺寸大小，和紙質(zhì)的圖表相比，電子海圖上的字是極小的，由于顯示屏的關(guān)系，標準允許電子海圖的尺寸大小只有270毫米X270毫米。除非你很合理地使用，電子海圖可能會造成一個讓使用者產(chǎn)生“視野狹窄”的趨向，因此它必須具有自然順暢的放大和縮小，以及屈卷表格的功能，而且還具備保持一個好的影像功能，就是當船通過這個地方，這個地方的布局能被很好地反映出來。如同之前所提到的一樣，備用的電子海圖能被有潛力地應(yīng)用正于此處。

電子海圖理念必須隨著顯示細節(jié)的變化而變化。盡管在不同的紙質(zhì)海圖上沒有什么很大的變化，在電子海圖上卻有著微妙的變化。對那些不了解狀況的用戶來說，在關(guān)鍵的時刻，他們可能會使用那些規(guī)模不恰當?shù)膱D表。在船的前方，圖表應(yīng)該經(jīng)常被展示出來，并且運用最大的尺寸，這樣做的目的在于在狀況良好的情況下識別潛在的危險。在設(shè)置正確的情況下，電子海圖會對某一條航線上的危險給予自動的警告并在圖表上顯示出來。如果這些警告使用戶感到詫異，那么他們自己的監(jiān)視是存在問題的。

除了以上關(guān)于屏幕尺寸的評價，電子海圖顯示器正在越變越大。但是，最重要的是顯示器的分辨率。一般而言，60英寸的顯示器像素和 20英寸的是一樣的，因此在如此大的顯示器上看一個完整的紙質(zhì)海圖會導致顯示模糊，無法閱讀。不幸的是在電子海圖能挑戰(zhàn)紙質(zhì)海圖之前，我們必須等待可負擔得起的高像素的顯示器誕生，這可能要等待很長時間。

電子海圖的最后一個主要缺點是用戶界面（例如控制裝置、菜單結(jié)構(gòu)以及顯示器的具體布局）沒有一個統(tǒng)一的標準。這和雷達以及其他的航海設(shè)備相似，但是這個系統(tǒng)的復(fù)雜性要高得多，第一次使用某種特定設(shè)備的用戶在瞭望之前必須很好地熟悉船上的系統(tǒng)。

這需要額外的培訓。該培訓應(yīng)以電腦和平板電腦為基礎(chǔ)。電子海圖理念體系應(yīng)為此做好準備，只有成功地完成國際海事組織電子海圖課程的培訓，才有能力使用電子海圖系統(tǒng)。因為只有非常熟悉裝在船上的實際系統(tǒng)，才能實現(xiàn)該目標。

電子海圖的優(yōu)勢

與使用紙質(zhì)海圖比較后，電子海圖的優(yōu)點大于缺點，很多并沒有在文章范圍內(nèi)指出。再次，如果用戶們想充分地使用電子海圖的優(yōu)勢并且避免濫用的風險的話，他們需要有正確的思維模式。

最為重要的優(yōu)勢（也是最容易被濫用的地方）是內(nèi)置的船位顯示設(shè)備，該設(shè)備持續(xù)顯示船舶在圖表上的位置。相反的，運用全球?qū)Ш叫l(wèi)星系統(tǒng)（例如GPS 全球定位系統(tǒng)）在紙質(zhì)海圖上繪制方位是非常乏味，容易出錯的。然而，電子海圖理念體系會從繪制方位上節(jié)省更多的時間，并把這些時間用于評估被顯示方位的完整性。用電子海圖進行完整性評估比用紙質(zhì)海圖容易得多，這不僅僅由于電子海圖能持續(xù)顯示方位，并且還由于電子海圖的安裝接近主控位置。

因此，在沿海水域，通常非常容易從GNSS(全球?qū)Ш叫l(wèi)星系統(tǒng))那里得到的位置與從窗戶外看到的景象聯(lián)系起來，以及與從其他主要的航海工具（特別是雷達）那里得到的信息相連接。事實上，每當船舶駕駛員看電子海圖時，他們應(yīng)該將其與其他資源作比較，并通過尋找來識別任何可能的位置錯誤。當與外界的視野作比較時，使用航向向上或迎風航行的模式尤其有用，要記住在保持總體意識時，要用不一樣的思維模式，這與使用北面向上的紙質(zhì)海圖略有不同。

另外，通過視覺以及雷達所獲得的軌跡線（LOPs）應(yīng)該被輸入進電子海圖中，并保持合適的間隔。在設(shè)計完備的駕駛艙里，單個的軌跡線，包括雷達范圍，能夠被快速地繪制好，然后轉(zhuǎn)入到電子海圖中來，由此來確認他們的船離他們指定的位置非常接近。通過這種方法檢查全球?qū)Ш叫l(wèi)星系統(tǒng)的精確性，特別是在障礙物總量少的狀況下。當然，應(yīng)該選擇連續(xù)的方位，但要使他們盡可能地不在一條直線上。

此外，在電子海圖思維體系中，單個軌跡線（LOPs）能自動被相關(guān)設(shè)備合并起來并形成一個方位預(yù)測裝置。電子海圖考慮到每個軌跡線（LOPs）所用的時間，并運用DR或是EP將其連接起來。這個功能真正的優(yōu)點在于它儲存軌跡線（LOPs）輸入數(shù)據(jù)以及由此而產(chǎn)生的方位，這為將來的運作提供了必要的參考。這取代了“船位誤差三角形”(cocked hat)的紙質(zhì)方位檢測，這項工作由港口國檢查官們承擔，他們檢測全球衛(wèi)星導航系統(tǒng)定位是否能被證實。

很高興看到由英國航海學會設(shè)計的ePelorus現(xiàn)在被用于船舶上。簡單地按一下按鈕就能通過陀螺儀視覺定位線，把數(shù)據(jù)發(fā)送到電子海圖，完整的評估時間也會明確的被顯示出來。這從很大程度上緩解了視覺壓力并進一步減少了障礙物。應(yīng)該注意的是電子海圖軟件更新非常必要，因為這樣就能與ePelorus相連接了。

航運的完整性

橋窗、來自電子海圖的信息和雷達能共同反映出完整的航運狀況——不僅僅只顯示出地理位置而已。擁有良好電子海圖理念體系的用戶會一直檢查信息的一致性。對于任何不一致的信息系統(tǒng)將會發(fā)出“一切并不順利，需要額外的關(guān)心”的警告。

當獨立的信息被相互連接起來后，避免危險變得尤為簡單。然而，需要被持續(xù)關(guān)注的是，雷達應(yīng)被用作首要的防撞設(shè)備，而電子海圖被用作首要的圖標援助工具。盡管這兩個系統(tǒng)中有越來越多的重疊信息，但從根本上來說，我們不能將這些重疊信息簡單地等同起來。

如果僅僅只有一個可用的數(shù)據(jù)來源，例如船舶自動識別系統(tǒng)顯示目標船從某地航?；貋?，這對該船而言很重要，需要被密切關(guān)注。是否因為信號干擾或設(shè)備裝置較差導致了雷達無法接收信號？是否由于能見度太差而導致了看不清航行路線？是不是全球衛(wèi)星導航系統(tǒng)或是陀螺儀出了問題？是不是船舶自動識別系統(tǒng)信號有誤？是信號故障還是海盜可能開始行動了？顯然任何決定都必須將這些問題考慮進去，此外需做好安全措施。

用戶必須知道如何用電子海圖在海上建立完整的地理位置。自動的DR/EP設(shè)備對于長時間檢查全球衛(wèi)星導航系統(tǒng)的重大錯誤起到重要作用。衛(wèi)星定位系統(tǒng)應(yīng)被融入到電子海圖中，這能對全球衛(wèi)星導航系統(tǒng)進行額外的檢驗。如果一個完整的全球衛(wèi)星導航系統(tǒng)發(fā)生故障，電子海圖內(nèi)置設(shè)備很有價值，無論是在沿海還是海上，它都能通過視角、雷達景象或衛(wèi)星定位裝置的輔助，長時間保持DR/EP定位。我們是否經(jīng)常聽到一些極其錯誤的觀點“沒有電子定位系統(tǒng)，電子海圖無法正常工作”？

利用這些替代方法，定期確認全球衛(wèi)星導航系統(tǒng)的定位完整性，并確保能在緊急情況下使用這些方法至關(guān)重要。此外，假設(shè)在全球衛(wèi)星導航系統(tǒng)完全喪失功能的前提下，舉行定期演習也十分必要。通過演習能確保在船上有相關(guān)的措施來應(yīng)對這樣的狀況，并讓所有工作人員了解該狀況。

信息顯示及路徑規(guī)劃

電子海圖另一個優(yōu)點是用戶能更多地控制顯示信息，這一點遠遠超過紙質(zhì)海圖。安裝好后，電子海圖就會顯示與本船相關(guān)的信息，而不是創(chuàng)造多余信息。尤其是在安全的水域，它可以很清楚地描述狀況（反之亦然）。然而，要做到這點，用戶必須完全熟悉安全“等高線”和“等深線”的用途，要進入淺于安全“等高線”水域，必須設(shè)置顯示信息及操作步驟，這樣才能順利地進入港口。如果沒有很好地設(shè)置電子海圖，那么在實際操作中可能會出現(xiàn)問題。

一個技巧熟練的用戶一定知道電子海圖的內(nèi)部信息設(shè)備，特別是“選擇報告”這個操作，它可以用來獲得圖上任意一點的詳細信息。例如 ,他們?nèi)绻荒芾斫饽硞€標志，一個簡單的操作就會顯示出關(guān)于這個標志的所有已知信息。具有電子海圖理念體系的用戶都知道如何快速的找到所需信息而不被其他相關(guān)信息所干擾。一般來說，使用電子海圖的視覺體驗和使用紙質(zhì)海圖的體驗完全不同，電子海圖構(gòu)成了一個重要的新型思維模式。

電子海圖理念體系還包括要對路徑規(guī)劃進程十分了解。運用電子海圖，可以很容易地設(shè)計出一個全新的路徑圖，或以之前的路徑圖為基礎(chǔ)進行設(shè)計。尤為重要的是在使用之前必須要進行人工檢查，并用最新的電子海圖數(shù)據(jù)進行修改，傳統(tǒng)的規(guī)劃信息（無論是紙質(zhì)或電子形式）能很好地支持這些工作。針對該狀況，必須向船員們發(fā)布最新的臨時或初步通告。

在進行核查的時候，最大尺寸的圖表必須被用于線路的所有部分。一旦人工檢查被執(zhí)行了，運行自動安全檢查很有好處。它會獨立檢查線路，但也要小心的調(diào)節(jié)，以防止總是跳出安全警告。有良好電子海圖理念體系的用戶應(yīng)知道自動檢查設(shè)備不是絕對可靠的，人工檢測也是如此。兩者同時使用可以降低錯誤發(fā)生的概率。更重要的是，手工檢查給設(shè)計者一個有價值的意識。這個意識是關(guān)于一個完整路線的設(shè)計。

迄今為止，電子海圖理念體系的最大挑戰(zhàn)是去克服一種錯誤的安全意識。問題在于電子海圖似乎十分準確，這很容易讓人錯誤地認為它永遠是100%正確的。即使在最好的情況下，其準確性還是受到潛在電子海圖數(shù)據(jù)質(zhì)量的限制，這一點能被100年甚至更久以前的調(diào)查所證實。（但是，當然，正確的理念體系總是能檢查目前CATZOC的情況）。在最壞的情況下 ,一系列的錯誤可能導致信息不準確。如果電子海圖想真正地變得更安全，所有的用戶都必須有一個正確的理念體系，該理念體系決定了所預(yù)見狀況的完整性，所有的航海決策都應(yīng)該建立在這個理念的基礎(chǔ)上。

最后，公司也需要有一個電子海圖理念體系，這尤其要體現(xiàn)在他們的安全管理系統(tǒng)上。從紙質(zhì)海圖轉(zhuǎn)向電子海圖預(yù)示著在很多領(lǐng)域?qū)l(fā)生具體的改變。這些領(lǐng)域包括風險評估、應(yīng)急準備、操作程序、演習與操練、培訓和強化。如果不這樣做，一個良好的用戶理念體系就達不到預(yù)期的要求并很好地被實現(xiàn)。

The ECDIS Mindset

Dr Andy Norris, FNI

The move to ECDIS has been firmly underlined as a means to further increase safety. A number of investigations presented to IMO in the last few years have shown that this is the expected result. But, in practice, will ECDIS further contribute to the overconfidence of some OOWs, resulting in an even greater narrowing of safety margins?

In fact, the safe operation of ECDIS necessitates the development of a new user mindset, which in many ways is quite different to that needed when using paper charts. The makings of a good mindset have to be instilled in users as a major component of basic ECDIS training and must not be obscured by an overemphasis on rote learning the specific operation of any one particular ECDIS. A firm grip of the fundamentals is essential; it not only helps instil the correct mindset but allows much easier familiarization when transferring between ships with different ECDIS on board.

ECDIS weaknesses

The ECDIS mindset fully appreciates the strengths and weaknesses of using an ECDIS-based system. Let’s start with its weaknesses. The most important of these is that ECDIS is an entirely electronically based system. It can therefore fail outright and can also develop faulty operation. In recognition of its vulnerability to failure, IMO has always required vessels to carry a backup to the main ECDIS unit. Although this could be a paper chart system, it is not a sensible choice for most ships for numerous operational and financial reasons. In general, the most suitable backup is a second ECDIS. To avoid familiarization complexities this ideally needs to be identical to the main ECDIS. A user with a proper ECDIS mindset ensures that the backup ECDIS is always efficiently involved in the ongoing navigational process, for example, by showing a different scale view to that displayed on the primary equipment. As well as the improved situational awareness that results, regular reference to the backup ensures that the system is immediately ready to become the primary, should the main system fail. It also helps to identify any developing faults in either system. In particular, it helps to ensure that the backup is properly loaded with the current route and upto-date ENCs.

The data standards for ENCs and ECDIS equipment are highly detailed, making it by far the most complex system on the bridge of a ship. From time to time, unexpected issues are uncovered. OOWs must always be aware that such problems can exist, together with the methods that are used to indicate these problems, which may include temporary procedures to be followed. Of course, the detail of the company’s Safety Management System must fully support this need.

In general, issues that arise from incorrect data coding of ENCs are quickly resolved by the hydrographic office that has compiled the data – although this can sometimes take some weeks. For a number of reasons, it generally takes rather longer for manufacturers to satisfactorily resolve equipment anomalies, which generally necessitate ECDIS software updates. The user needs to be aware of the software status of the equipment in use, including any unresolved issues. Unfortunately, many shipping companies do not yet appear to have latched onto the issues connected with software updates for navigational equipment, despite firm guidance from IMO, such as that given within MSC.1/ Circ.1389, issued in December 2010.

However, it is easy to be unduly anxious about ECDIS anomalies. In practice, their number has been relatively small and they can all easily be kept in mind by a well-informed user, provided good procedures are in place and the user mindset is completely switched on to the fact that such issues can exist. Their significance to safety on a correctly used ECDIS is likely to remain of a relatively minor nature but, nevertheless, they could lead to accidents if ECDIS is ignorantly used.

Display size and user interface

A significant weakness of ECDIS is the size of the chart display. Compared to a paper chart this can be minuscule the standards allow the display area to be as small as 270 x 270 mm. Unless used sensibly, ECDIS can create a tendency for the user to develop ‘tunnel vision’. It must therefore become natural to not only be regularly zooming in and out and scrolling the chart but also to retain a good mental image of the general layout of the area in which the ship is traversing. As previously noted, the backup ECDIS is potentially useful here.

The ECDIS mindset also has to work with the changes in displayed detail that occur when zooming. Although this is essentially the same issue as working with different scale paper charts, the effects can be more subtle. To the unaware user, this can lead to inappropriately scaled images being used in critical situations. The chart must be regularly scrolled ahead of the vessel, using the largest scale data, to identify potential hazards in good time. When properly set up, ECDIS should give automatic warnings of charted hazards on the immediate route. If these warnings come as a surprise to the user then it is their own monitoring that is at fault.

Despite the comments on screen size above, ECDIS displays are getting larger all the time. However, of more importance is the display resolution. In general, a 60 inch display has the same number of pixels as, say, a 20 inch version and so trying to view a full scale paper chart image on such a large display would just result in an unreadable blur. Unfortunately we must wait for affordable high resolution displays to become available before ECDIS rivals the area of a paper chart. This could be a long wait. The last main weakness of ECDIS is that the user interface, such as the controls, menu structure and the detailed layout of the display, are not rigorously standardized. This is similar to the case for radar and other navigational equipment but is magnified by the complexity of the system. A user new to the particular equipment must therefore become properly familiarized with the system on board before undertaking a watch.

This requires an additional element of training. It makes great sense for this training to be computer or tablet-based. The ECDIS mindset should be ready for this, understanding that while the satisfactory completion of a course complying with the IMO ECDIS Model Course requirements is a statement of competence to use ECDIS, this is only the case provided there has been appropriate familiarization with the actual fitted system to be used onboard ship.

ECDIS strengths

The weaknesses of ECDIS are dwarfed by its strengths compared to the use of paper charts, many of which lie outside the scope of this article. Again, users need the right mindset if they are to use these strengths to their fullest extent, and avoid the perils of misuse.

Perhaps the most important strength – and the one most prone to misuse – is the built-in continuous display of the ship’s position on the chart. Conversely, on a paper chart plotting position from a Global Navigation Satellite System such as GPS is tedious and prone to error. However, the ECDIS mindset knows that much of the time saved in plotting the position should be readdressed to assessing the integrity of the displayed position. Integrity assessment is much easier with ECDIS than when using paper charts, not only because the position is continuously displayed but also because ECDIS is generally installed close to the main conning position.

Therefore, in coastal waters, it is generally very easy to correlate the GNSS derived position with the view from the bridge windows, as well as with information from other prime navigational aids, particularly radar. In fact, every time the OOW looks at ECDIS, they should make a mental correlation with these other sources, seeking to identify any possible positional errors. The use of course-up or head-up mode can be particularly beneficial when making the correlation with the outside view, bearing in mind that a subtly different mindset is required in maintaining overall awareness compared to using a North-up paper chart.

In addition, visual and radar derived Lines of Position (LOPs) in coastal waters should be input into ECDIS at appropriate intervals. On a well designed bridge, single LOPs, including radar ranges, can be rapidly made and transferred to the ECDIS in order to confirm that they pass very close to own ship’s indicated position and therefore provide an excellent check on GNSS accuracy, especially with the low overall latency that can be achieved. Of course, consecutive bearings should be chosen such that they are as far out of alignment as possible.

Furthermore, the ECDIS mindset knows that subsequent single LOPs can be automatically combined by the equipment to form a positional estimate. ECDIS takes into account the time at which each LOP was applied and uses DR/EP techniques to perform the merger. The real beauty of this functionality is that it stores the input LOP data together with the derived position for future reference. This replaces the ‘cocked hat’ positional checks on paper charts so beloved of port state inspectors when assessing whether the position given by the GNSS position is being appropriately verified.

It is good to see that the ePelorus proposed by The Nautical Institute is now available for fitting to ships. A simple press of a button sends the data of gyro-referenced visual LOPs to the ECDIS, complete with the time reference of the measurements. This considerably eases the task of applying visual sights and further reduces latency. It should be borne in mind that a software upgrade to the ECDIS may be necessary to connect to an ePelorus.

Navigational integrity

The view from the bridge windows and information from ECDIS and radar jointly establish the best overview of the complete navigational situation – not just position. A user with a good ECDIS mindset is constantly checking all this information for consistency. Any inconsistency provides a warning that all is not well and that extra care or understanding is needed.

When independent sources of information agree, avoiding hazards becomes much more straightforward. However, care must be taken to ensure that radar is always used as the primary collision avoidance aid and ECDIS as the primary charting aid. Despite the increasing overlap of data than can be displayed on both systems, fundamentally neither is the equivalent of the other. If there is only one source of available data, for example a target’s AIS return from an area navigationally significant to own ship, great care is needed. Has it been missed by radar because of clutter or poor equipment set-up? Has it been missed visually because of poor visibility? Are there GNSS or gyro problems? Is the AIS signal in error? Is the signal a spoof, perhaps pirate initiated? Any decision must obviously take into account all such questions, and may ultimately require a very wide safety margin. The user must also know how ECDIS can be useful in establishing positional integrity in ocean waters. The automatic DR/EP facility is invaluable in keeping a check on GNSS gross errors over long periods. Celestially fixed position can also be plotted onto ECDIS as an additional check on GNSS. In the event of a complete GNSS failure the inbuilt ECDIS facilities are invaluable in maintaining a DR/EP fix over an extended time, whether in coastal or ocean waters, assisted as appropriate, by visual and radar sights or celestially derived position. How often do we hear the highly erroneous statement that ‘ECDIS cannot work without an electronic position fix system’?

Use of these alternative methods in the regular confirmation of GNSS positional integrity maintains the skill base needed to use them under emergency situations. In addition, it is essential that there are regular drills that mimic complete loss of GNSS, ensuring that the onboard procedures for such a situation are workable and fully understood by all.

Information display and route planning

Another huge advantage of ECDIS over paper charts is the control that the user has over what is displayed. When well set up, ECDIS shows all the charted information relevant to own ship and is far from creating any information overload. In particular, safe water areas (and vice-versa) can be very clearly depicted. However, to do this the user must be fully conversant with the role of safety contours and depths, setting the display detail and knowing what procedures to apply when having to enter waters less deep than the available safety contour, perhaps to enable port entry. If ECDIS is not properly set up then real problems can occur.

A skilled user is mindful of the embedded information facilities of ECDIS, particularly the ‘Pick Report’, which can be used to gain detailed information about any point on the chart. For instance, if they do not understand a particular symbol then a simple operation will display all known information at that point. The user with an ECDIS mindset knows how to rapidly find the required information and will not be phased by all the other information displayed that is also relevant to that point. In general, the visual experience of using ECDIS is very different to that of paper charts, forming an important part of the new mindset.

Having an ECDIS mindset also means being very knowledgeable about the route planning process. It is easy to design a route from scratch on ECDIS or to use a previous route as a basis. It is very important, however, that the route is manually checked and refined using up-to-date ENC data before each use, supported by all the traditional planning information, whether in paper or digital form. This especially needs to include the latest Temporary and Preliminary Notices to Mariners.

When undertaking this check, the largest available scale chart must be used for all portions of the route. Once a manual check has been performed it is highly beneficial to run the automatic safety check. This independently rechecks the route but needs to be carefully set up to prevent it coming up with a host of overcautious warnings. A user with a good ECDIS mindset will recognize that the auto check facility is not infallible - but neither is a check by a human. Performing both reduces the probability of an error. Even more importantly, the manual check gives the planner an invaluable awareness of the complete route.

By far the greatest challenge to the ECDIS mindset is in overcoming the tendency to a false sense of security. The problem is that ECDIS often appears to be highly accurate and it is all too easy to assume that this is true 100% of the time. At best, its accuracy is limited by the quality of the underlying ENC data which may have been taken from surveys made 100 years ago or more. (But, of course, the correct mindset always checks the current CATZOC status.) At worst, a combination of errors can make it highly inaccurate. If ECDIS is to really improve safety, all users must have a mindset that can determine the likely integrity of the perceived situation and use this as the basis for establishing the optimum navigational decision.

Finally, the company must also have an ECDIS mindset which should particularly be reflected in their Safety Management System. Migrating from paper charts to ECDIS implies detailed changes in such areas as risk assessment, emergency preparedness, operating procedures, drills and exercises, training and familiarization. Without this action, the requirements for a good user’s ECDIS mindset cannot be fulfilled.

Andy Norris is a Fellow of The Nautical Institute and is currently the Vice-President of the Royal Institute of Navigation. He is the author of the NI published textbook ECDIS and Positioning, which is extensively used by training colleges and shipping companies.