Geographic information systems (GIS) are computer programmes designed for mapping and the analysis of geodata; i.e. data that can be linked to particular positions. In this exercise you will use GIS to analyse The Sea Stallion’s observations from the voyage to Dublin. There are several free GIS programmes available on the Internet.
- Import the voyage data into your GIS. Map the voyage (you may need to adjust the length and width of the column to a format which your GIS can work with). You could find and download a suitable free background map from the Internet.
- Find and remove erroneous data. (Tip: Search for impossible values; for example course>360º or width>90º.) Note that it may not be the whole record which is erroneous. For example, the anemometer may have malfunctioned without there necessarily being errors in the other measurements. (This can of course be done in another programme before being imported to the GIS.)
- You can also choose to remove records from when the ship has lain stationary in harbour.
- Make thematic maps with the various recorded data as the variable. For example, a map that uses colour to show the ship’s speed. You may need to remove records where the instrument in question was malfunctioning.
- Look at the trace of the ship. Are there places where there are unexpected changes in course and/or speed? What could be the reason(s) for this? (Tip: Look in the logbooks and diaries and see what happened on board at that particular time.)
- Use GIS in solving the exercises maximum speed, rowing, tacking abilities, turns and the speed diagram. Does it provide new opportunities for displaying the results?