THE TOOLS OF THE TRADE · 2014. 1. 23. · 2 - Passage Planning . 3 – Passage Monitoring . Including fixing the position . Traditional Navigational Methods Admiralty Manual of Navigation

THE TOOLS OF THE TRADE A Brief review of the tools required to

Navigate with ECDIS

Captain Richard Dunham Senior Lecturer

Australian Maritime College

ECDIS Performance Standards

“1.5 ECDIS should reduce Navigational Workload compared to using paper charts”

Navgational Workload

1 - Maintaining the chart outfit Including corrections and updates

2 - Passage Planning 3 – Passage Monitoring

Including fixing the position

Navgational Workload

1 - Maintaining the chart outfit Including corrections and updates

2 - Passage Planning 3 – Passage Monitoring

Including fixing the position

Traditional Navigational Methods

Admiralty Manual of Navigation suggests Time taken to carry out the navigational tasks associated with fixing the ship’s position is 1 minute per fix, for a practiced navigator

Traditional Navigational Methods Chart

Paper, from hydrographic office Position fixing method

Visual bearings, ranges from radar, positions from Electronic Navaids

Tools to plot the position Parallel rulers/ set squares, pencil, eraser, compasses and dividers

Techniques To ensure track monitoring (e.g. parallel index, transferred position lines etc.)

Charts

Electronic charts as good as paper charts What more is there to say? Mariner’s understanding of Vector Charts……..

Position Fixing Methods

Visual bearings, ranges from radar, positions from Electronic Navaids

Easiest from a user’s point of view is automated input from GNSS

Display of position

From GNSS is straightforward, and , by now, familiar to most seafarers Progress along track is also displayed in the form of past positions

Best Practice

Fix ship’s position by more than one means Eg Visual bearings and radar ranges, Or crossing visual bearings with position from GNSS.

Then:- Run up a DR and/or EP to look ahead

With ECDIS?

Estimated Position (EP) is given by the own ship vector Versatile and needs no input or calculations by the operator Saving Time, and reducing workload

But……..

This relies only on the input from the electronic position fixing system connected to the ECDIS, providing both position and course and speed over the ground (aka made good)

Why do we need other methods?

Just because best practice says we should? No Navigation Safety Confirming the Integrity of the position

Without Cross checking

Performance Standards Tools to be available

Boundary crossing Cross Track limit Second independent source of position (where possible) Adequate number of points, moveable EBL’s VRM’s, Fixed Range Rings and other symbols (Appendix 3 of performance Standards)

Ability to plot manual bearings and ranges Able to shift own ship position.

Why?

To be able to carry out traditional navigation processes? To be able to use ECDIS if our GNSS fails? To be able to confirm GNSS is operating effectively? To insert user developed chart corrections and amendments? To highlight dangers to other users? To amplify instructions within the passage plan?

How?

By annotating the chart with text By fixing our position and plotting the results on the ECDIS By extracting data from the chart – Parallel Index, Safety bearings By adding symbols or shapes to indicate new information

Entering a fix – an example To plot a fix. Obtain bearing/range information. Access the correct menu on the ECDIS Select two EBL/VRM to provide crossed position lines Enter the correct range and reciprocal of bearing Move the VRM/EBL to the object(s) used for the fix Select the correct menu for enter fix Select correct format for fix (Radar/visual/GPS/etc) Put cursor over MPP, and select Position entered. Total time = 2 minutes 30 seconds for a practiced student

Results?

This part of the system does not reduce workload, neither does it simplify operations It provides a number of distractions Because it is difficult, it tends not to be used.

What is missing?

1- A simple, easy to use method of entering position line data (Preferably automated to some degree.) 2 -The facility to extract parallel index information, so that route can be easily monitored on radar, separate from GNSS input 3 – Fix symbology to be standardised

What helps

Radar Overlay Leaving switched on clutters the picture, but intermitted use, about as often as traditional position fixing, can help to confirm the integrity of the GNSS position. Also helps to identify other errors such as heading input error, radar range error.

Thank You

.Questions?