I have not had an opportunity to really tinker with it yet. I've been involved in other research (geoscientist) and haven't had time to commit other than background research. I hope to make some progress this weekend.
These are just two sketches I pulled off the web to give me a starting point. But any suggestions you have will be appreciated. You stated my plan exactly: make the ping(transducer) sample at the same rate as the GPS. And then I need that data to go into the CSV file with the GPS data. So at a point, the GPS read (X,Y), the ping simultaneously read Z, and the point was saved as (X,Y,Z) on the SD card. This is really basic stuff for any electronics hobbyist I'm sure. I'm trying to learn.
And I do not know what the code concerning the analog inputs is all about. I don't plan on using analog inputs for this project. That guy ran his accelerometer through an analog input, and his GPS through a serial. I was actually wondering if I should run the ping through a separate serial port. I have a mega if that is the case.