Be in Command by Knowing These ECDIS Safety Settin...

ECDIS has been the talk of the town. On every inspection on board, compliance with ECDIS procedures has been top agenda for the inspectors.

It will not be a new thing to say that good passage planning is the key for safer navigation. ECDIS now being a part of passage planning contributes to the safe navigation.

I had covered ECDIS in lengths earlier on the topic like

• ordering and correcting ENC
• Plotting navigational warnings on ECDIS

In these two posts I covered about the process of correcting the ENCs. Can we say we are all set if ENCs are corrected for Weekly corrections, T&P corrections, Navigational warnings and navtex warnings ?

But what if the settings on the ECDIS are not what it should be. Wrong settings pose even bigger threat to the safe naviagtion than the uncorrected ENCs.

In this post I will discuss about the what and how of all the settings on ECDIS.

Safety Settings

It is all in the name. Safety settings sets the safety parameters according to the ship’s static as well as dynamic particulars. That is a change ECDIS brought from the traditional paper charts. For example see this chart and I will ask one question.

Can we say that blue part on this chart is shallow water ?

It is and it is not. For a small vessel with less draft, it is not a shallow water. For a big container ship with deep draft, may be.

So you see, the colors on the paper chart may not represent the shallow waters for all the ships. But on the ECDIS these can be set by the user according to their draft and other parameters.

There are 4 safety settings

• Safety contour Setting
• Shallow contour settings
• Deep contour setting
• Safety Depth setting

To enter a value for these settings on JRC ECDIS, go to

chart -> settings  and then choose “S-57/C-Map/ARCS.

 

Now Let us discuss about these settings in detail and what values we need to enter in these settings

Shallow Contour setting

A contour is a line separating a minimum depth area. For example a 10 meter contour will be a line that separates waters below and above 10 meters depths.

The contours are in the value of 5, 10, 15, 20, 30 and so on.

Shallow contour value need to be used to tell ECDIS what is the value of shallow waters for our draft. This is the value of depth below which it is definite for the vessel to get aground.

The shallow contour value need to be equal to or more than the draft of the vessel.

Let us say the vessel’s draft is 9 meters and we enter the shallow contour value of 9 meter. The ECDIS will display 10 meter contour line as the shallow contour. If 10 meter contour is not available, it will take next contour as the shallow contour for the vessel.

The shallow contour lets the navigator know that between 0 meter depth and the shallow contour, the area is not navigable at all.

Safety Contour setting

Safety contour is the contour line above which we can navigate without any water depth concern.

So what is the depth of water required for the vessel to navigate without any concerns ? Off course it is the depth that complies with the company’s UKC policy.

Now again let us see it with an example. Vessel’s draft is 9 meters and at maximum speed, the expected squat is 1.1 meters. The company require the vessel to have UKC of 10% of the draft.

I assume you know the UKC calculation method and can easily arrive to the conclusion that this vessel would need 11 meters of water depth to navigate.

I have taken here the simplest of the case. In reality you need to follow your company’s UKC calculation sheet to arrive at the depths required to comply with UKC policy. This may take various factor such as sea conditions, increase in draft due to rolling, sea water density and the tide.

But the idea is to know the minimum depth of water at which you will comply with the company’s UKC policy.

This water depth becomes the safety contour setting. So if we enter 11 meters as safety contour setting, it will show 15 meter contour as the safety contour.

Some companies may give simpler instructions for the safety setting in the navigational manual. One form of these instruction can be based upon the draft of the vessel.

When safety contour value is entered in the ECDIS, it gives a safety contour line depths above which would meet the UKC requirement.

Safety Depth setting

So far we have only been talking about contours. We have not said anything about the actual safe depth. Safety depth is the only depth setting on ECDIS.

Safety depth is the depth of the water we can safely navigate upon. And it might sound repetitive but it is the depth that satisfies the UKC policy of the company.

In ECDIS we need to enter this minimum depth. It is same what we calculated as a simple example in safety contour setting. And as I said in that section, we need to follow the UKC calculation form of the company which may account for number of factors to calculate the safety depth required.

But the question is why do we need safety depth settings when we can navigate in waters above the safety contours ? This is because of two straight forward reasons

i) The depth above safety contour may not always be navigable.

This is in case of a shallow depth at one point in the navigable waters. Although we might be navigating in area above safety contour, this isolated depth pose a danger. Safety depth highlights this danger.

ii) The depths below safety contour may not always be non-navigable.

We can understand this If you allow me to again go through the safety contour value we entered. We entered the value of 11 meters and when we enter this value the ECDIS will take next available contour. This will be 15 meter contour.

Now the depths between 11 and 15 meters are navigable for us but it will show below the safety contour. So in the area between shallow contour and safety contour, safety depth will show the depth on which we can navigate.

Let us say we set the safety depth to 16 meters. On the ECDIS, all depths below 16 metes will be shown more prominently (in Black compared to others in grey color).

Deep water contour

This is a relative term and user is free to set as per what he believes could be deep water for him. For me deep water could be 50 meters while for others it could be 30 meters or 100 meters.

But there can be number of ways we can use the deep water contour setting.

For example you can set the deep water contour to show the maximum anchoring depths where vessel can drop anchor. So if your vessel can anchor maximum 105 meters depth, you can set the deep water contour to 100 meters.

Or if you are about to do ballast water exchange, you can set the deep water contour to 200 meters. This way you can easily see just by the color on the ECDIS if you are in depths where ballast exchange can be done.

The deep water contour setting can be used in number ways and navigators can use this to the way they wish to use it.

Differentiating the safety settings on ECDIS

Now let us see how the ECDIS screen will look like with all these settings. So let us say vessel’s draft is 9 meters and vessel require 14 meters depth to comply with company’s UKC policy.

So we have these settings

• Shallow contour: 9 meters
• Safety depth:  14 meters
• Safety Contour: 15 meters
• Deep Contour: 50 meters

And when I enter all these numbers in the ECDIS, this is how a ECDIS screen would display these settings.

If you notice, for safety contour ECDIS has taken the 20 meter contour because 15 meter contour is not available.

There is another option in the ECDIS to use two colors to show these areas. When this option is selected, following will happen

• Safety contour and deep contour will merge
• Shallow contour and safety contour will merge

Or we can say that light blue and blue color will merge and become blue. Same way, grey and white color will merge and become white.

So there will be only two colors. One to show the shallow waters and other to show the navigable water.

Even in the two color display, it is not that we cannot navigate in the shallow waters. This is because it is showing the contour and not the depth.

In our example, the dividing line will be the 15 meters contour. The area below this contour will show as shallow waters (blue color). But as the safety depth is 11 meters (which will be below 15 meters contour), we can navigate in the shallow waters provided the depth is above 14 meters.

Danger detection settings

Entering the safety settings will warn us with an alarm when vessel enters in shallow waters. But when it gives the alarm it could be too late by then.

Danger detection settings can help in giving pre-warning of the dangers ahead. We only need to define the area in which we need the ECDIS to warn us.

We can define the area in two ways

• Vector area
• Sector Area

Vector area defines the area in length and width. Sector area defines the area in radius and width (angle).

Vector area defines the area in length and width. Sector area defines the area in radius and width (angle).

Let us define this area on JRC ECDIS. On JRC ECDIS go to Menu, Settings and then choose Alarm settings.

 This will open the Alarm settings pane.

Under Vector and Sector section, you can define the area you want the ECDIS to look ahead. Once these areas are defined you can turn these on by going to “Ownship/Track” and then choosing “Settings”.

You can then choose to either “Vector area” or “Sector area”. You can even go to alarm settings page by clicking on “Set alarm limit” from danger detection section.

When you choose to display “Sector area”, it will look like this and ECDIS will trigger alarm if it detects any danger in this area.

When you choose to display “Vector area”, it will look like this and ECDIS will trigger alarm if it detects any danger in this area.

Alarm Buzzer settings

I have talked about different safety settings on ECDIS. But these settings are of no use if do not have the alarm buzzer volume on. If the volume of the buzzer is off, ECDIS would not be able to alert the navigator.

But there are times when we need to keep the buzzer off. Like in high traffic density area when we are constantly monitoring the traffic. In this case frequent alarms will be of lesser value.

Navigators must use their professional competence to decide when they need to turn on the alarm buzzer.

On JRC ECDIS to turn on the volume of the alarm buzzer, go to “Main”, “Setting” and then choose “buzzer volume”.

This will open a pane from where you can increase or decrease the volume of different type of alerts.

Conclusion

I am a big advocate of use of ECDIS on board for navigation. In my opinion ECDIS is making the shipping safer. Sure there have been number of incidents because of user’s interpretation of ECDIS display but the increase in training and good practices has helped to cover many gaps.  Correct use of safety settings in ECDIS will definitely take it one step ahead .

Knowledge of what these safety settings mean can help in that.