Global Positioning Systems (GPS) are commonly found on recreational boats, and while a good navigation aid, they should not be relied upon (like any other electronic equipment dependent on battery power).
A GPS is able to provide a latitude and longitude, updated almost continuously. This
can then be plotted on a chart and should be verified with a compass.
There have been a number of navigational incidents, where boats have run aground and into obstructions, attributed to people using GPS data alone.
Some positions given by GPS will need to be adjusted due to differing datum.
As with all fixes, the GPS position should be checked against something else.
A GPS is not a substitute for sound watch keeping and navigational practices and should be used only in conjunction with other aids to navigation.
Consider the following when using GPS and/or chart plotters:
- Masters should still maintain a proper lookout while the vessel is underway to identify any approaching hazards.
- Zoom to the largest available accurate chart scale. If the zoom recommended exceeds the accuracy scale limit then a warning message is displayed on the screen.
- It is advisable to switch the unit on and select the correct chart datum before departing.
- GPS units require time to initialise, and the master needs time to assess the accuracy of the position information prior to starting the voyage.
- The accuracy of GPS units can be compromised by power failures or poor
- Always ensure your electrical charts are updated with supplier upgrades.
- When going to a way point in a straight line, check what is in between your boat's initial location and the way point.
- Be aware of areas under construction or development as hazards may change regularly.
A good way of maintaining safety information is through Notices to Mariners, which can be found on the Maritime Safety Queensland website. www.msq.qld.gov.au
Before using your new GPS, you are obligated to familiarise yourself with the strengths and weaknesses of the equipment.
As a starting point, it is recommended that that GPS users undertake navigation and GPS courses currently offered by both Volunteer Marine Rescue (VMR) and the Australian Coast Guard.