ENC Display

"What percentage of time should we have an ENC displayed on an ECDIS, 100% or just as required?"

 "What percentage of time should we have an ENC displayed on an ECDIS, 100% or just as required?"

This applies to ships with a standalone set up through to ships with multiple screens. On a standalone it would be very difficult to always have an ENC on view and comply with the need to keep a watch using all available means. Why do we want the ENC on view?

RESPONSE

(from Dr Andy Norris FNI)

Ask the question “What percentage of time should we have a paper chart displayed on the chart table, 100% or just as required?” Why do paper charts not elicit the same question?
IMO MSC/Circ. 982 ‘ergonomic criteria for bridge equipment and layout’ stresses the need for highly important or frequently used information to be permanently displayed. It would be impossible to argue that radar and ECDIS need not be permanently (and separately) displayed. Also, it is never OK to use ECDIS as a primary aid for collision avoidance, even when displaying radar and AIS targets; a type approved radar display is the only device legally sanctioned for this.

(from ECDIS Ltd)

Definitive answer (assuming that your primary means of navigation is ECDIS (i.e. dual ECDIS fit): If there is an ‘adequate’ ENC available then it should be displayed on the ECDIS. However, as long as the primary ECDIS is displaying an appropriately scaled ENC for the ship position i.e. being used to conduct the navigation, then the second ECDIS could be used for spatial awareness, which could mean use of an RNC. It is advisable, however, that the ECDIS terminals are properly labelled to indicate unequivocally which one is the Primary terminal and which is the Secondary. It is also advisable that the Primary is always displaying the best scale ENC for the ship position.

If your primary means of navigation is paper then it does not matter whether you have got an ENC or an RNC displayed on your ‘standalone’ ECDIS. However, if you are using ECDIS as the primary means of navigation, then if an ENC exists of an appropriate scale for the ship position, then it should be displayed. If you are displaying an RNC, then it will not alarm when it encounters dangers unless manually constructed information with a danger attribute is overlaid on the RNC and is encountered by the ship symbol or the Safety Frame/Anti-grounding Cone. ECDIS is designed around the ENC product, which is why it functions best with an ENC (see IMO Circular 207).