Use the parallel rule on the chart provided, line up the ruler from your current position and your destination.
“Walk” your parallel rule across the chart to the nearest compass rose, until the rule crosses the centre. Note the degrees in the outer circle in the direction of your heading. This is your heading in relation to True North. To obtain your boat’s compass direction heading, deduct 10 degrees for the magnetic variation from your true heading and steer on this course. The (magnetic variation in the Whitsundays is approx 8.3 east we use 10 to simplify)
Compensate for the tidal currents as necessary.
Check on your chart to ensure you have clear water when navigating from points A to B and you are safely clear of dangerous shallow water or underwater reefs. If necessary, set 2 or 3 courses in appropriate directions to avoid such areas.
The side of your chart shows degrees and minutes of latitude. Each degree (which is indicated by a small circle next to the number) is divided into 60 minutes. (Minutes are indicated by a small stroke on the top right hand side of the number). Each minute equals one nautical mile (1852 metres). On the side of the chart, you will see markings such as 20° 10′ and then markings every 5′. The distance between 10′ and 15′ is therefore 5 nautical miles. To calculate distance, measure the distance of each leg of your trip and transfer to the side of the chart. As a rough guide divide the total distance by 5 to obtain the time in hours to be allowed for your trip. Make allowance for tides, winds and waves, as this might increase the trip’s time by up to 30% or more.
Almost all Whitsunday navigation is “line of sight” most of the islands are large and the use of land transits (the lining up of headlands, islands or prominent features) is a simple and effective navigation tool. You can usually see the next destination you are heading for with no difficulty. However rain squalls or smoke haze will limit visibility from time to time.