It is important that your instruments are properly calibrated, and that we have details of the instruments you use, so we can include their accuracy when modelling data. So you need to go through the calibration process when you first start using the software, and repeat it whenever you make any changes to your instruments. You will find the calibration under the Configure menu.
The first task is to specify the make and model of your GPS, from the drop-down lists. If your equipment is not listed, just type in the name and model. Also, check the boxes if you are using Differential GPS (DGPS) or EGNOS (which may be referred to as WAAS, the US equivalent).
Next, enter your depth sounder details. Many depth sounders have a choice of transducer, with different models having different beam angles and transmission power, as well as operating on different frequencies. As this affects the quality of the data, having your transducer details is a great help.
Now it is time to get out your tape measure. Mark a reference point on your centreline, such as the rudder stock, companionway hatch or mast, and measure the fore and aft and transverse distances to your GPS antenna and depth sounder. Distances forwards and to starboard of the reference point are positive, or negative for distances aft and to port. Also, measure the height of your GPS antenna above the waterline. These measurements needn't be any more accurate than a tenth of a metre.
Finally, we need the depth offset for your transducer. The first thing to do is to use a weighted line and measure the depth of water each side of your transducer, and average the values to get the depth. Next, look at your instruments and display the depth below the transducer or, if your instruments cannot do this, set the transducer depth offset to zero. The difference between this and your measured depth is the transducer offset. Finally, enter the draft of your boat.
This completes the calibration process.
It is important that your instruments are properly calibrated, and that we have details of the instruments you use, so we can include their accuracy when modelling data. So you need to go through the calibration process when you first start using the software, and repeat it whenever you make any changes to your instruments. You will find the calibration under the Configure menu.
The first task is to specify the make and model of your GPS, from the drop-down lists. If your equipment is not listed, just type in the name and model. Also, check the boxes if you are using Differential GPS (DGPS) or EGNOS (which may be referred to as WAAS, the US equivalent).
Next, enter your depth sounder details. Many depth sounders have a choice of transducer, with different models having different beam angles and transmission power, as well as operating on different frequencies. As this affects the quality of the data, having your transducer details is a great help.
Now it is time to get out your tape measure. Mark a reference point on your centreline, such as the rudder stock, companionway hatch or mast, and measure the fore and aft and transverse distances to your GPS antenna and depth sounder. Distances forwards and to starboard of the reference point are positive, or negative for distances aft and to port. Also, measure the height of your GPS antenna above the waterline. These measurements needn't be any more accurate than a tenth of a metre.
Finally, we need the depth offset for your transducer. The first thing to do is to use a weighted line and measure the depth of water each side of your transducer, and average the values to get the depth. Next, look at your instruments and display the depth below the transducer or, if your instruments cannot do this, set the transducer depth offset to zero. The difference between this and your measured depth is the transducer offset. Finally, enter the draft of your boat.
This completes the calibration process.