Hey Sue, all you need to get it to look like mine is a really windy day, some flat water and a serious disregard for you own health!
If by 'seeing it on your computer' you mean looking at the SD card after it has been inserted in you computer, then that is correct. The 'clear all' menu item just clears what is in the GT-31's own memory (Data logger and Genie).
You probably don't want or need to clear the files off your SD card, even if you have copied them to your computer. The SD card can easily hold many years of saved files, especially if it is the max size of 2GB. It can be useful to have a backup copy on the card. I just checked one of my GPS cards and it has over two years of session files on it that only fill 105MB of space leaving 1.76GB free! I recon I am right on that card for space for about another 15 years!
This is what you get on the SD card when you use the SAVE ALL function in the MISC menu:
The SBN fie is already there as it written to the card in real time. (Note that a new .SBN file is created each time the GPS is turned on)
The SBP file is the file saved from the internal memory, often called the 'Data Logger'. This is a 'circular' type of file. It will continue from where it left off before each time the GPS is turned on, but when the memory is full it will just start to overwrite the earliest part of the file. To me, the big advantage of the 'DELETE ALL' is that it clears the internal data logger memory. This means that the next time you sail you will have only that session in the data logger (SBP) file. The advantage of saving this file is that it is considerably smaller than the .SBN file so it can be uploaded or sent by email much faster. It also has the advantage that if you turn your GPS off during the day and then turn it on to sail again, there will only be one file for the day (if you cleared the memory before you started), whereas there will be two .SBN files that may have to be joined to analyze a days session
The .SPD file is the contents saved from the Genie (Text file)
The.BIN is.........something...... that is not useful to us as far as I know. No need to copy and save it on your computer.
Hope this helps.