Blog 113 == From 14th Century 'Rutters' to Electronic Charts = From Crows Nest Lookouts to ECDIS

At the outset, I would like to iterate that I am continuing with my 'Sunday Gentleman' phase and am writing about things that attracted me, interested me during my sailing days, the interest heightened by noticing the rapidness with which technology changed to the extent that seafarers, as operators and service people, were forced to necessarily speed up their knowledge response by training themselves. In no way do I profess to be proficient in their use nor do I profess to have the intimate knowledge of the technology used, to call myself well versed in the subject.

The field of Navigation was, to me, always a distant desire, never fulfilled. I acknowledge that I referred to a lot of publications and read a lot, before committing anything to paper. I also acknowledge that I have quoted certain sections verbatim, for the sake of clarity.

Instruments on the Bridge - Over the Years

Gyro compass

My first interaction with a gyro compass was, as a 5th Engineer, I was sent to assist the Electrical Officer in overhauling a motor. A separate room, labelled ‘Motor Room for Gyrocompass’ - hot, noisy - contained a motor driving another motor, both large in size. The second motor had a specific purpose - to give an output of constant voltage and frequency. This piece of equipment is now an anachronism, having been replaced by an AC Servomotor 5% the size of its noisy predecessor.

We engineers used to be gently chided whenever there was a ‘black out’, as it would upset the stability of the gyro compass, which would take between 8 to 12 hours to re-stabilise.

I recollect the several occasions when ‘changing the liquid’ in the equipment was carried out by a Second Mate and Electrical Officer - all done perfectly.

These days it is mandatory to designate and call an ‘Authorised Service Provider’ for all work on a Gyrocompass.

A Port State Control Inspector or a Classification Surveyor makes it a point to see the Company’s contract with an ‘Authorised Service Provider’ during their inspections or audits.

Gyro Compass on Ships

Old Ship Auto Pilot with Gyrocompass repeater

Cutaway of an Anschütz gyrocompass - Wikipedia

A gyrocompass repeater - Wikipedia

AC Servomotor now

Gyrocompass now

Awaiting type approval

New type gyrocompass

New Gyro change over system

Digital compass repeaters

Paper Navigational Charts Give Way to ECDIS

Then

Quote (from "Marine Insight')

"Traditional navigation methods use basic tools including a Breton plotter and single-handed dividers. Navigators use soft pencils to draw position marks and lines on paper charts which can easily be rubbed out after a trip.

To pinpoint a position on a chart, dividers are used to measure the distance to the nearest horizontal and vertical grid lines from the position being measured."

Unquote

The relationship between Paper navigation charts and the Second Officer were endemic. Charts, whether electronic or paper, were his domain. One would always find the Second Mate putting in those extra hours needed to classify, correct and catalogue all charts and requisitioning the missing or outdated ones.

I have always been fascinated with a Second Mate correcting charts and by the numerous inputs that a Second Officer requires before he does so.

Let me quote from a part of an excellent ‘Marine Insight’ article written by Abhishek Bhanawat, at that time a Chief Officer.

Quote

An updated and corrected chart folio system comprises of Chart correction Log and Folio Index, Admiralty Chart catalogue, Admiralty Sailing Directions , Weekly Notices to Mariners , Annual Summary of Notices to Mariners, Admiralty List of Lights , Admiralty List of Radio Signals , Admiralty Tide tables , Chart – 5011 Symbols and abbreviations to be used on charts. The following points to be considered in order to maintain updated chart folio onboard:

• The chart correction log should have details of all charts present onboard with index of corrections (temporary and preliminary also) mentioned against each chart number. All the charts and publications are to be corrected on weekly basis following instructions provided in weekly notices to mariners and the correction numbers to be entered in the same index mentioned above against chart numbers respectively, so that it can be used as a quick reference to check status of corrections for any chart

• There should be a designated chart supplier or service provided on a timely basis without delays to supply new charts and new editions applicable to the folios onboard. Other than that weekly Notice to Mariners, Annual summary of Notices to Mariners, their supplements should be provided

• There should be equipment onboard and services to receive Navigational warnings, and Navtex warning

• Whenever a new chart or new edition is published, Weekly Notices to Mariner carry a notification of the same. On receiving a new edition or a new chart the chart correction log is to be updated with the relevant folio number against the chart number in the index and ‘NC’ or ‘NE’ to be inserted adjacent to the chart number in the correction index. The chart to be verified for any pending temporary and preliminary corrections and navigational warnings

• On receiving a chart or a notification through weekly notices to mariners which replaces a previous chart , insert in the chart correction log ‘replaced by’ or ‘cancelled by’ against the mentioned chart. The folio number to be inserted on the replacement chart received.

The Admiralty Chart Catalogue (NP 131),Weekly Notices to Mariners , Cumulative Notices to Mariners and Annual summary of Admiralty Notices to mariners are important sources of keeping a Chart folio system updated and corrected. For guidance on correcting charts Admiralty has published – How to Correct Charts the Admiralty Way which describes various forms of corrections applied to charts and upkeep of folios.

The sheer number of sources that the Second Officer needs to consult to correct just one chart is mind boggling, yet it was done.

The importance of keeping charts updated can be understood from the below incident.

Real life incident: Due to negligence of a navigating officer a vessel was not allowed to enter a port for 2 days. After 2 days special permission was granted by USCG to the vessel upon request by the agents. The vessel did not have the latest edition of approach charts for the Port of Baltimore. The new edition had been published 4 weeks ago and the vessel had received notification of the same. The USCG during their annual inspection pointed out the error and the vessel was fined and allowed to berth after two days only when agents procured the new edition.

It is therefore important that during correcting charts the navigating officer has to exercise due diligence and care.

Real Life Incident: Near Batu Berhanti Light in Singapore Straits a wreck is marked by 4 cardinal buoys surrounding it. During chart corrections the notice read as ‘Insert Isolated Danger Mark’ adjacent to the light. The duty officer misread it as ‘Delete’ and instead of inserting deleted the mark. The courses were laid from that area and while in transit it was observed that the vessel passed very close to the Isolated Danger Marks which were wrongly indicated on the chart.

Breton Plotter

The minute details recorded on each navigational chart is astounding

And then came ECDIS - Electronic Chart Display and Information System

Although the originators are unknown, the pioneers in this field were the International Hydrographic Organisation from the early 1980s.

The switch from analogue to digital, the advent and generalised use of computers and the tremendous progress made in solid state technology were all instrumental in changing a very important niche operation of a ship, as ECDIS was introduced and quickly became mandatory in certain sectors, as IMO climbed on to the band wagon.

What started off as Electronic Navigational Charts, produced by Hydrographic Societies, became an electronic extension of the paper chart that could be seen on a screen. When interfaced with other technologies, it transcended into the Electronic Chart Display and Information System, ECDIS.

ECDIS, in the initial stages, had its share of teething problems, forcing ships to carry paper charts also. The problems were more in updating charts through discs, which had to be physically sent to vessels and the interfacing with other equipment.

It is only after 2015 that, as band width of the internet through satellites increased, that automatic updates started taking place on a commercial scale. Dedicated satellites for such purposes speeded up the process.

The equipment that had the most far reaching impact on Bridge Procedures, necessary knowledge and training was the ECDIS. Software skills became the yardstick with which a person’s skill set was calibrated and grew in prominence in comparison to dividers and plotters. The ‘track ball’ had replaced the parallel scale.

It was a radical change from the ship of 50 years ago.

Radars and ARPA

Radar by itself is an acronym (for Radio Detection and Ranging), using the X-Band and S-Band for early detection of objects within its range.

"The x-band, being of higher frequency is used for a sharper image and better resolution whereas the S-band is used especially when in rain or fog as well as for identification and tracking."

The 1950s and 1960s saw the development and installation of many brands of radar on merchant ships, but there were always limitations.

When the ARPA (Automatic Radar Plotting Aids) were gradually introduced in the 1970s, these were ‘stand alone’ units, used side-by-side with existing radars, not mandatory till the 1980s.

"ARPA (Automatic Radar Plotting Aid) is a computerised additional feature to the Radar. ARPA takes feed of the own ship’s course and speed, and target’s course and speed, and calculates the collision avoidance data and simplifies the need for the users to calculate the data themselves. ARPA provides various other additional features and controls as well."

Courtesy Wikipedia

An ARPA Plot

Credit : Aditya Mohan, Second Officer

As technology advanced, more and more features were added till it became the mainstay in close quarter navigation. Depending on the Captain, navigation using ARPA sometimes superceded traditional methods like checking bearings, plotting on charts and altering course accordingly.

Presently, the ARPA is married and interfaced with the ECDIS, yielding numerous observations and outputs and has become the central focus when the vessel is in transit.

The main advantages of the use of ARPA - Quote (from Wikipedia)

The primary function of ARPAs can be summarized in the statement found under the IMO Performance Standards. It states a requirement of ARPAs: "to improve the standard of collision avoidance at sea: Reduce the workload of observers by enabling them to automatically obtain information so that they can perform as well with multiple targets as they can by manually plotting a single target". As we can see from this statement the principal advantages of ARPA are a reduction in the workload of bridge personnel and fuller and quicker information on selected targets.

A typical ARPA function gives a presentation of the current situation and uses computer technology to predict future situations. An ARPA assesses the risk of collision, and enables operator to see proposed maneuvers by own ship.

ARPA provides all the necessary information for the radar users and helps in saving a lot of critical time from observing a target to finding the data using radar plotting and calculations. Collision avoidance and detection data is thus readily available to the radar users in no time, just by a click on the target.

While many different models of ARPAs are available on the market, the following functions are usually provided:

1. True or relative motion radar presentation.

2. Automatic acquisition of targets plus manual acquisition.

3. Digital read-out of acquired targets which provides course, speed, range, bearing, closest point of approach (CPA, and time to CPA (TCPA).

4. The ability to display collision assessment information directly on the Plan Position Indicator (PPI), using vectors (true or relative) or a graphical Predicted Area of Danger (PAD) display.

5. The ability to perform trial maneuvers, including course changes, speed changes, and combined course/speed changes.

6. Automatic ground stabilization for navigation purposes. ARPA processes radar information much more rapidly than conventional radar but is still subject to the same limitations. ARPA data is only as accurate as the data that comes from inputs such as the gyro and speed log.

ARPA provides all the necessary information for the radar users and helps in saving a lot of critical time from observing a target to finding the data using radar plotting and calculations. Collision avoidance and detection data is thus readily available to the radar users in no time, just by a click on the target."

===== Blog 114 Contiunues on the same subject =====