Electronic Nav Equipment

Question 1

Echo sounder limitations

Answer 1

• Electrical noise (from transducer)
• Cavitation (propeller bubbles)
• Draft mark (stylus position wrong)
• Salinity (speed of sounds increases)
• Shallow water
• Wrong scale being used
• Biological noise (e.g. whale)
• Mechanical noise (E/Room)
• Different layers (beam refracts)

Question 2

ECDIS Limitations

Answer 2

• Software virus
• Hardware failure
• Sensor failure (gps, gyro, radar, echo sounder)
• Datum errors
• Zooming in (can give false sense of space)
• Overreliance
• Full info not visible on some scales

Question 3

What frequency does AIS transmitt on?

Answer 3

VHF

Question 4

What ships are required to have AIS A?

Answer 4

• All pax
• All ships on international voyages over 300GT
• All domestic ships over 500GT

Question 5

How often is static, voyage and dynamic information trnasmitted on AIS?

Answer 5

• Static and voyage every 6 mins
• Dynamic every 2sec to 3mins depending on speed of ship and if it is turning

Question 6

What are the different ECDIS standards?

Answer 6

S-52: Standardized display and symbols
S-57: Defines format of ENC data and how it is transferred
S-58: Quality control of ENCs
S-63: Security and authentication

Question 7

Mandatory inputs for ECIDS as per IMO?

Answer 7

• Speed
• Position
• Heading

Question 8

Max number of targets AIS can track?

Answer 8

250

Question 9

What International bodies have a role in the ECDIS system

Answer 9

IHO: standards of ENCS
UKHO: Publisher and correction issuer
IMO: Equipment and training standards
IEC: Electrical safety standards

Question 10

What certificate does ECDIS come under?

Answer 10

Safety equipment certificate will be recorded in your form P

Question 11

What are the requirements for a ship to go papeless?

Answer 11

• Approved ECDIS system with back up system and back up power supply
• Risk assesment for all propable voyages
• Type specific training for all officers
• Take me home folio

Question 12

What guidance would you give the duty officer for safe use of ECDIS and how to set up?

Answer 12

• Enter parameters correctly on ECDIS
• Setup alarms (safety contours / off course alarms)
• Check inputs are correct
• Customise display with correct layers
• Check charts are up to date
• Route check to be done visually
• Do not over rely on ECDIS use window
• Cross check position with visual means

Question 13

What are the manadatory stations for NAVTEX?

Answer 13

• A, nav warning
• B, met warning
• D, search and rescue warning
• L, Navigational warnings additional to letter A

Question 14

Errors of GPS

Answer 14

• Multi path
• Clock error
• Jamming
• Propogation error (from upper atmosphere)