ELECTRONIC NAVIGATION AIDS IN PRACTICE
The skipper of a cruising motorboat is planning a passage from Port Fitzroy to S. Kilda. The passage is to be conducted during the hours of darkness and restricted visibility is also forecast. The vessel is fitted with a range of electronic aids to navigation including multifunction display, radar, AIS transceiver, echo sounder, a heading sensor, speed log as well as a GNSS receiver. An almanac and up-to-date electronic and official paper charts for the area are also on board.
1. An auto-routeing function is used to plot a route for the intended passage. a) Suggest what types of issues the
icon might indicate on this route?
b) Refine the position of the following waypoints and describe how you would verify your arrival at each one using electronic aids to navigation.
i) WPT8 ii) WPT9 iii) WPT10 iv) WPT11
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Explain which electronic aids to navigation or navigational alarms might be particularly useful during the following legs of the journey:
a) Between WPT1 and WPT8 b) Between WPT8 and WPT9 c) Between WPT9 and WPT10 d) Between WPT10 and WPT11
3. The tablet screenshot shows a real-time repeat of the vessel’s chartplotter display.
a) What are the advantages and disadvantages of using a tablet as a repeater in the manner described above?
b) In terms of viewing AIS data, what advantage is there to using a repeater app rather than a website or app that utilises data shared over the internet?
4. As you go past Dawson Harbour and approach S. Kilda the visibility worsens to around a quarter of a mile. You use radar to assist your approach and entry.
a) Refer to RYA Chart 3 to assess how distinctively the following locations will appear on radar: i)
The coastline in front of the United Ores chimneys?
ii) The headland of Taunton Point? iii) The commercial dock/pier? iv) The approach to the marina, including the bridge?
b) How might you revise your route into the bay due to the restricted visibility? c) What factors would you consider before deciding whether or not to continue into S. Kilda Marina?
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