International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 1

Number1

March 2007

10 Things They Should Have Told You About

ECDIS

D. Edmonds

PC Maritime Ltd, Plymouth, UK

ABSTRACT: The aim of this paper is to highlight some operational and system issues that are frequently en-

countered by navigators trying to get to grips with ECDIS. This information should also be beneficial to man-

agers and owners who are making decisions about which system and chart format to buy, and the priority that

should be given to formal training ahead of a mandatory requirement.

1 WHAT IS THE SYMBOL THAT LOOKS LIKE

A SCREW HEAD?

This is what one Pilot said to me, referring to the

Isolated Danger symbol which seems to turn itself on

and off with a will of its own. Many of the symbols

that appear on an ENC are immediately recognisable

to navigators but some are not; one of the most im-

portant that an ECDIS operator must know is the

Isolated Danger symbol.

Here's why. We had a vessel trialing Navmaster

ECDIS with ENC and ARCS charts. They came to

anchor off Teesport on the east coast of England.

The ARCS chart to the right shows four wrecks in

the vicinity of the vessel's position. The ENC to the

left shows three wreck symbols; but the wreck to the

west of the vessel is depicted by an Isolated Danger

symbol because its depth at 30 m is less than or

equal to the safety contour value set by the operator.

So here is a fundamental difference between

ECDIS with ENCs and other chart display systems.

The chart display, and sometimes symbology,

changes depending on how you set ECDIS up.

In this case, if the safety contour value were set to

10 m the symbol would change back to a wreck.

Fig. 1. An example of the use of the Isolated Danger symbol on

an ENC

2 WHY DOESN’T MY ENC SHOW

SOUNDINGS?

ECDIS gives the operator three display levels: Base,

Standard and All Other. The chart detail shown at

each level is tightly specified in IHO S-52. During

type approval an ECDIS is carefully checked against

the IHO produced ENC Test Data Set to ensure that

the information displayed on the chart conforms to

the Test Data Plots for each display level.

The ECDIS performance standard specifies

that

the Standard display shall be used when a chart is

first displayed by ECDIS and that the display can be

set to Standard by a single key press.

All well and good, except that the operator may

have configured his chart display to his preference

with more or less information than that given by the

Standard display (eg by the addition of soundings)

only to find that when a new ENC is loaded or he se-

lects Standard display, settings revert to the IHO-

specified level. I can imagine on occasions that this

is quite perplexing. Soundings are not included in

the Standard display and many operators question

the rationale for this.

How to get around it? Well, I can only speak for

Navmaster ECDIS. The solution there is to create a

custom display based on the Base or Standard dis-

play with the addition of soundings. This means you

can quickly switch back to your preferred display.

3 KNOW YOUR SYMBOLOGY

Fig. 2. Unreliable Soundings

The master of a very large bulk carrier asked

"How do I get rid of the circles around soundings?"

Actually, the circles mean that the data (ie the

sounding it-self) is unreliable.

Points 1 – 3 raise several issues:

1 For mariners there is no simple, accessible, refer-

ence to ENC symbology. For paper charts there is

BA5011 (INT1) Symbols and Abbreviations used

on Admiralty Charts. For ENC symbology the

best that is available is "ECDIS Chart 1". PC

Maritime provides access to ECDIS Chart 1

through the Navmaster help menu. However you

have to know what you are looking for and the

IMO PS for ECDIS Section 2.4, 3.3, 3.4 & Appendix 2

explanation given for individual symbols is

limited to the symbol name.

2 In my opinion it is not the role of ECDIS manu-

facturers to provide a reference. This should come

from an official body such as the IHO.

3 Some ENC symbology is open to misinterpreta-

tion or perhaps no interpretation at all, due to un-

familiarity.

4 The importance of ECDIS training, even if the

system is not being used as the primary form of

navigation. The reality is that with an ECDIS on

board, some operators soon pay lip service to pa-

per charts while their focus shifts to the ECDIS

display, arguably with good reason (in view of

better situational awareness etc). But there are

dangers if operators have not had basic training.

4 WHAT IS THE DIFFERENCE BETWEEN S-57

FORMAT AND SENC FORMAT

DISTRIBUTION?

ENC data is distributed in S-57 format by organisa-

tions such as the Admiralty, Primar and other na-

tional hydrographic offices. ENCs in S-57 format

have to be translated into the internal data format or

SENC (System Electronic Navigational Chart) used

by the ECDIS before they can be displayed.

In April 2002, the IHO

agreed that the ENC dis-

tributor could perform the translation from S-57 to

SENC format on shore, subject to the approval of the

hydrographic office producing the ENC, and deliver

ENCs in ready to run SENC format.

S-57 is a generic format and it is mandatory that

all ECDIS must be able to install ENCs in this for-

mat. SENC formats are proprietary and therefore

specific to manufacturers or groups of manufactur-

ers. The main SENC formats are C-Map's CM-ENC

format supported by over 20 ECDIS manufacturers,

Transas's SENC service and SevenCs DirectENC

service.

Why is this important? Well, when you take

delivery of ENCs in S-57 format, they have to be

copied, converted, verified and decrypted before they

become available for display. Even the IHO

acknowledges that this "is not the most efficient

means of storing, manipulating or preparing data for

display" [1]!.

When you take delivery in SENC format, all the

checks and conversions have taken place and the

data is ready for display. The most noticeable effect

is the difference in installation and updating time.

IHO Technical Resolution A3.11

Here are the results of tests that I undertook last

year:

Table 1. Comparison between S-57 ENC and SENC installation

times (all available cells, Sept 06)

S-57 ENC format

Disk copying (5 base CDs)

1.5 hours

Decryption, verification and installation

11.2 hours

Total

12.7 hours

Apply Update CD

4.03 hours

CM-ENC SENC format

Disk copying (1 DVD)

13 mins

Apply licence

5 mins

Total

18 mins

On line update

A few minutes

ECDIS is a real-time system and will often need

to be operational during chart installation and updat-

ing. Indeed the ECDIS performance standard states

that "the (update) implementation procedure should

not interfere with the display in use" [2]. I can only

speak for my company's ECDIS which will process

chart installation and updating as a background task,

leaving the ECDIS fully operational. However there

is no doubt that a system that involves less disk

copying, no conversion or decryption and takes min-

utes to install and update rather than hours is

intrinsically the safer option. Amongst my reasons

for saying this are:

− CD \ DVD drives are generally not type approved.

There is a risk of data being miscopied, particu-

larly under heavy vibration conditions, which

could cause ENCs or updates to fail verification

checks later in the installation.

− it does not make much sense to carry out verifica-

tion and quality checks on ENC data at this stage

of the operation. If the operator finds that a chart

has failed to install, due to a critical error, there is

very little he can do about it -apart from call his

chart supplier, who will call the chart producer

and so on. For less critical errors, the operator

should not be faced with numerous warnings

about minor infringements to the S-57 product

specification, which mean little to him. Far better

that all these checks are carried out ashore and the

data delivered to the vessel as near as possible

"ready to run".

− There will be occasions when ENCs are required

urgently, within minutes; lengthy installation pro-

cedures could stop a vessel sailing!

5 ALARM MANAGEMENT - SAFETY

CONTOURS

ECDIS requires an alarm if “within a specified time

set by the mariner, own ship will cross the safety

contour” [3].

The Safety Contour is required to default to 30 m

on start-up [4]

Hence, it is imperative that the

operator sets a safety contour and time appropriate

for the intended voyage, leg of voyage or sailing area

otherwise Safety Contour alarms will be

meaningless or so intrusive as to be ignored. It is

possible for a vessel to receive no safety contour

alarms at all. For example vessels transiting the

River Thames would not receive any safety contour

alarms with the default 30 m safety contour. Some

operators might, at first, be relieved by this but they

would be losing significant benefits. A correctly set

safety contour provides increased contrast between

safe and shallow water and highlighting to the safety

contour itself. Examples of appropriate time settings

range from very low (say 1 or 2 minutes) on a bendy

river like the Thames where a vessel will always be

very close to shallow water, or very high (say 1 hour

or more) in mid ocean where plenty of warning

might be needed of shallow water ahead.

In Navmaster ECDIS we have added an

additional parameter so that the operator can define

the width of the “searchlight” that looks for safety

contours and warning areas. For the river example,

this can be set very narrow (down to 1 x beam) and

in mid-ocean quite wide (10 x beam at its farthest

limit). And the searchlight area can be displayed so

the operator can see what, if anything, is triggering

an alarm or indication.

Fig. 3. Guard zone set at 1 minute and 5 x beam

6 ALARM MANAGEMENT – PROHIBITED

AREAS \ SPECIAL CONDITIONS

ECDIS requires an alarm or indication if “within a

specified time set by the mariner, own ship will

cross the boundary of a prohibited area or of a

geographical area for which special conditions

exist” [5].

In most important shipping areas ENCs will be

populated with many area related cautions. For ex-

ample a one-leg route from Dover to Calais gener-

ates 49 warnings crossing areas with special condi-

tions. In practical terms, allowing ECDIS during

normal position monitoring to generate an alarm

every time the vessel is approaching one of these ar-

eas is excessively intrusive.

The value of these warnings is at the planning

stage, when they provide an essential reference for

the navigation officer. In most cases operators will

want to turn off alarms generated by areas with

special conditions.

7 TRAINING

Today ECDIS training is not mandatory, although

STCW part B requires that operators should be fa-

miliar with every bit of equipment on the bridge be-

fore they use it. Some, eg the International Chamber

of Shipping, are quoted as opposing mandatory

ECDIS training, their view being that it is "inappro-

priate to force officers to take courses to operate

equipment that they either never use or will not

come across for several years by which time their

training will be out of date or forgotten about" [6].

I have already given some reasons why ECDIS

training is important, even when ECDIS is not used

as the primary form of navigation as is the case with

most installations so far. However, for the moment it

seems that national administrations would rather see

ECDIS adopted as an aid to navigation, with all the

ensuing safety benefits, than place barriers in the

way, such as making generic and type training man-

datory at a sub-ECDIS level.

To run paperless however, the training and audit

requirement is clear. The master and watch-keeping

officers must be able to produce appropriate docu-

mentation verifying that generic and type-specific

ECDIS familiarisation has been undertaken. Generic

training is based on the IMO model course on the

operational use of ECDIS (IMO course 1.27). Type-

specific training is provided by manufacturers [7].

And this could be a barrier to the uptake of “full”

ECDIS. The ship owner or manager has to be

confident that he has a pool of appropriately trained

officers before he takes this step.

Typically generic ECDIS training from approved

training institutions runs to 3 days and type-training

from manufacturers amounts to another 2 days.

There is significant cost involved and the industry

would benefit from seeking ways of reducing the

cost of training personnel.

One way forward is to develop Computer Based

Training (CBT) modules covering appropriate areas

of the IMO Model Course. It is arguably too expen-

sive and inefficient to send people to a classroom for

days, with all the attendant travel and subsistence

costs, simply to be taught aspects of ECDIS that

could be equally if not more effectively learnt via

CBT (eg Legal Aspects and Requirements, Types of

Electronic Chart, Terms and Definitions (S-52, S-57)

Reference Systems, etc). Far better to send officers

pre-taught about the basics to simulator courses of

reduced length but greater focus on the operational

issues of working with ECDIS as a primary form of

navigation.

A similar approach can be taken by manufacturers

by providing good training manuals, preferably in

electronic “CBT” form, and ideally recording opera-

tors completion of each element.

8 RTFM - READ THE FLIPPIN' MANUAL

I know you wouldn’t have thought of this by your-

self.

All manufacturers like to think that they produce

easy to use and intuitive user interfaces and most do,

to a greater or lesser extent. At its simplest, ECDIS

will automatically recognise GPS input, load the ap-

propriate chart, and follow the vessel’s progress.

However ECDIS is much bigger and more complex

than suggested by this simple chart plotting function.

How many other systems are you aware of that:

process continuous streams of data from half a dozen

or more instruments; handle complex graphic

images; keep extensive records; provide drawing

tools, manage large databases; monitor position

against chart data and planned route; manage charts

and updates, provide reports and so on, all in real

time? ECDIS may not have the depth of an

application like Micro-soft Word, with features that

most people never use, but it makes up for this by

making nearly every feature it offers relevant to most

operators.

Most manufacturers will have tried to make their

operator manuals complete and informative. Reading

the manual will alert operators to the tools that are

available and the general way in which the system

works. It then remains to try each feature in turn, as

and when time allows. It should not take more than a

few weeks to become fully comfortable with the op-

eration of any ECDIS.

And if RTFM fails, email or call the manufacturer

for help. There should be a ready explanation to help

you and if there isn’t you may be highlighting some-

thing that can be done better. Often the manufacturer

won’t know if you don’t tell him that something is

either not working or more difficult to do than it

should be.

9 KNOW YOUR CHART DRAWING TOOLS

The ECDIS Performance Standard3 specifies the

tools that should be provided for chartwork and posi-

tion monitoring. This does not specifically include

Parallel Indexing tools even though many would

consider the use of these one of the most effective

position monitoring tools. Indeed, a Royal Navy

contact commented recently that they consider their

passage plans incomplete if full use of parallel

indexing is not specified and this would typically

involve half a dozen planned PIX per leg (our

product, Navmaster ECDIS offers the navigator the

ability to set any number of PIX).

Is parallel indexing an appropriate tool to use in

an ECDIS? I raise this question because ECDIS gets

its position from GPS and if the GPS is in error any

PIX (or any other position related range or bearing)

will be in error to the same degree. Some would ar-

gue that PIX is more appropriately used as a radar

based tool but then some, more expert in this area

than me, say that AIS (ie GPS) is more accurate than

Radar.

Fig. 4. Parallel Index Line

So doesn’t it all come down to using all the

sources of information at your disposal and cross-

checking one against the other? And to do that you

need to know how to use all the tools that your

ECDIS provides.

Appendix 3

10 UNDERSTAND INTERFACING

With IMO’s recent call for the development of an e-

Navigation strategy

data transfer will become ever

more important to keep bridge instruments working

correctly and shore side stations correctly informed.

Navigation officers need relevant systems knowledge

so that they can undertake basic troubleshooting and

keep the systems that are being relied on so widely

running smoothly - another training need that should

not be overlooked.

Fig. 5. Boxes and wiring

Fortunately there are no great mysteries about the

interfacing between ECDIS and marine instruments.

It is well worth becoming familiar with data transfer

protocols and troubleshooting strategies as many

seemingly fatal problems (eg no position input) can

be solved with a bit of know-how, perseverance and

remote help from manufacturers.

Marine data is transferred using the NMEA 0183

standard, which is a simple ASCII (ie text) format

that defines how data is transferred in a sentence

from one instrument to another, eg:

$GPDTM,W84,,00.0000,N,00.0000,E,,W84*41

$HEHDT,340.8,T

$GPGLL,5120.5091,N,00312.7769,E,090813,A*2D

Most sentences begin with a $ followed by a two

character talker ID. In the foregoing data, GP is GPS

and HE is Gyro. Then follows a three character sen-

tence identifier: DTM is datum; HDT is heading,

and GLL is geographic position, latitude and

longitude. Even without a knowledge of sentence

structure you can extract some meaning from each

“the collection, integration and display of maritime information

aboard and ashore by electronic means to enhance berthto-berth

navigation and related services, safety and security at sea, and the

protection of the marine environment” definition from the

International Association of Marine Aids to Navigation Lighthouse

Authorities (IALA).

sentence, eg, the heading above is 340.8°T and

latitude 51°20.5091’N.

!AIVDM,1,1,,B,35Vi7f50000AEw<M@ee;wCLB00

00,0*3B

The exception is AIS which transmits a sentence

beginning with !. The Talker ID and sentence identi-

fier are the same as for other instruments but the re-

mainder of the sentence is encapsulated, meaning

that compression techniques are used to send more

information than could be achieved by a straight

ASCII sentence. Consequently you cannot read an

AIS sentence directly.

For troubleshooting, most ECDIS will provide a

means of viewing the raw data that is being received

on the com ports used to interface with external in-

struments or you may be able to use the Microsoft

Hyperterminal program to view com ports.

It is well worth exploring these facilities because

with this basic knowledge there are several strategies

you can use for troubleshooting:

1 No data received from a particular instrument?

Open the com port viewing window or program

and check to see if sentences are present with the

appropriate talker ID, eg GP for GPS, HE for

Gyro, RA for radar etc. If not the problem is most

likely wiring or com port allocation or there could

be a simple setup requirement in the instrument

itself. Many GPS require NMEA output to be

turned on and individual sentences to be activated

before they are sent. Much time can be wasted

cursing the ECDIS when the fault lies with the

source of the data.

2 Data present but unexpected characters present?

eg $GPGLL,58 0.5 91,N,0∋312.7769,E,09⁄813,A

*2D. The data has been corrupted either by faulty

wiring or electrical interference. Check the wiring.

3 Data on a port complete nonsense? Quite likely to

be caused by the baud rate for the port being set

incorrectly. Most NMEA talkers output data at

4800 baud although some may have an option to

transmit at 9600 baud. AIS always transmits at

38400 baud. Setting com ports to the correct baud

rate usually results in the data becoming readable,

which is confirmation of the cause of the

problem. Another cause of unreadable data can be

incorrect wiring, often as simple as the polarity

connection being the wrong way round. Positive

connected to negative and vice versa; if the case,

wiring reversal gives an immediate result.

REFERENCES

See paragraph 3.3 of S-52 and IHO Technical Resolution

A3.11

IMO Resolution A.817 (19) Performance Standards For

Electronic Chart Display And Information Systems

(ECDIS) Section 4.5

IMO Resolution A.817 (19) Performance Standards For

Electronic Chart Display And Information Systems

(ECDIS) Section 10.5.3

S-52 Colour & Symbol Specifications For ECDIS Section 3.2

IMO Resolution A.817 (19) Performance Standards For

Electronic Chart Display And Information Systems

(ECDIS) Section 10.5.4

'Safety at Sea' magazine, “The future of ECDIS Training”

March 2007, page 26.

P18 Facts about charts and carriage requirements Primar

Stavanger – IC-ENC Working Group on information

(PSIWG) 1st Edition November 2004.