Future ENCs

Future ENCs

I was coming back to Bangalore after a fairly long time.

I had reached quite early in the morning which gave me ample time to keep my appointment. But not enough time for sight-seeing. I wished I had the energy to roam around for a few hours in the city under the summer sun. Instead I waited in the airport lounge itself. I took this opportunity to strike up conversations with other passengers to glean some local knowledge.

Whilst waiting in the long queue for the pre-paid Auto I started talking to a young fellow beside me. He turned out to be a friendly guy from the IT sector. I learnt he was an M-Tech in software engineering and hailed from Bhatkal.

‘I have been to Bhatkal. A sleepy little village north of Malabar coast. There is an islet there called Pigeon Island, and a fishing harbour close-by.’

That guy was surprised that I knew the place.

I was there about 15 years back during the course of a hydrographic survey. Bhatkal could qualify as one of those parts of Incredible India. Beautiful, sun-kissed and un-spoilt; having a wonderfully temperate climate. I remembered it as a picturesque village on the sea-shore. I was glad to know that IT had penetrated deep into these villages.

The Auto-ride was surprisingly comfortable and not as bad as it would had been in Andheri. The peak-hour traffic hadn’t yet built up. A distance of 12 kms in the heart of the city was covered in 40 minutes.

Peeping out from the Auto I watched the early morning crowd. Schoolchildren seemed to be happy looking forward to the day. A middle-aged man was crossing the road at a traffic signal. He was in a hurry weaving around the standing vehicles before the lights changed. He had a lap-top in his hand, without its carrying case. As if he didn’t bother to pack it up nicely before leaving for the office.

I don’t think I had seen so many lap-tops anywhere else in the world as I saw in Bangalore that day. In the airport, at restaurants and other public places. Instead of thinking of renaming it as Bengalooru perhaps the state politicians should call this place laptop-nagar. It would be original and apt.

I was in Bangalore to attend the marriage of Shwetha. I used to know Shwetha as a quiet little child. That day she was looking radiant and enchanting.

At the marriage Bhavan I met some old friends and fellow seafarers.

People asked me about the world of electronic charts.

They all agree that ECDIS has been a good thing for the shipping industry.

Watching your ship progressing on the Electronic Chart on the Bridge is a dream-come-true for the Master. The screen gives him an informed picture of the situation outside. Dangers to navigation from proximal targets can be correctly assessed without too much of an effort.

What else would a Master want from the ECDIS?

As he looks out of the Bridge windows he can see the waters around. But he is unable to see underneath the water. Is it possible for him to somehow penetrate the water, as if with a powerful x-ray vision and see the seabed underneath?

What if he could visualize the column of water on top of the seabed corrected for the tides at that point of time?

Suppose if the Master could see the hull of his ship immersed in the water at its current draft. The ship’s draft continuously being corrected for the height of the waves and the vessel’s squat and heel. If he could only see the under-keel clearance and measure the changes when the vessel varied her speed and/or applied the rudder.

The three-dimensional graphics using rotation matrix technology already exists in the video-games that the kids play. Can we use this technology to view the oceans and our ship moving on it? When can the navigators get such charts?

Most navigators are aware of the projection errors of a chart. Simply put, it is the distortion that occurs when a marine cartographer transfers a part of the spherical earth on a flat sheet of paper. But how many know about the sounding selection algorithm which skews a sea-bed to be artificially raised on a chart. The important thing to know is that all these errors on paper charts have being carried forward to the electronic charts which are being depicted on the video screens today. Including the algorithm for selecting soundings.

When selecting soundings to be put on a chart, the cartographer is handicapped by the limitation of available space. Too many soundings clutter the chart, especially on small-scale charts. So he follows a rule for picking up depths from a fair sheet:

- As far as possible, all shoals are picked up.
- Space permitting, the deeps between the shoals are picked up.

Many times, especially when the seabed is uneven, space does not permit all deeps to shown. This means that the shoals which appear on the chart will artificially raise the seabed. This is deliberately done so as to err on the safe side, but the fact remains that the seabed is not correctly shown on the chart. It also means that the chart is not suitable for applications which require the undulations of a sea-bed to be accurately shown. Anchoring is one such example, trawling is another.

The soundings that appear on the chart are a few selected depths out of the thousands which appear on the fair sheet. There are many more which remain forever inside the echo-roll. The chart drawn on a flat sheet of paper or flat screen does not show all this information.

Modern surveys today are carried out with multibeam sounders connected to data-logging systems. These instruments collect many times more information than single-beam echo sounders with manual read out. And yet the way we prepare our charts have not changed.

The fact is that the chart that you see today, even if it is an ENC, contains only a small fraction of the data that was actually collected in the field. The vast majority of the data lies unused in the Hydrographic Offices and repositories all over the world.

A lot of research is going on in C-MAP to improve the appearance of the charts. A research is going on for example in the integration of land and sea maps. This has always been a problem earlier because the datum for land and sea data are not same. Soon we will have 3D land sat maps integrated with the sea maps.

C-MAP OceanView software permit the vector charts to be viewed as a 3D picture. We have to remember that presently this 3D model is based on scanty data. Only on large scales charts where there are sufficient depths this feature can be safely used.

At IHO there is a committee working on the upgradation of ENCs from S57 to S100. The electronic charts prepared in accordance with the S100 standards promises to be of the state of art technology. It proposes to overcome the limitations of S57 ENCs. They expect this version of chart to be available only after 2012.

To protect the customers, it is planned to be upwardly compatible from S57.

It is going to be a long time before these charts becomes a reality. But when these future electronic charts become available to the Master, his dream would be realized. He will be able to use the underwater information in the chart in a way he wants.

Off course, the chart developers still have to cope up with the logistics of exchanging the vast amount of data in a practical manner.

Perhaps if commercial charting organizations are included by IHO in the programs for developing future ENCs there could be a faster development.

These future ENCs would then become a tool not only for the navigator but for many others who work out there in the sea. The fishermen, oil explorers, submarine cable layers and many others. In fact it could give a fillip to the nascent ocean-related industries.


Capt. Raj S Chakravorty