I use Water explorer to keep a record of where i am, it keeps a log of miles, Locks and time of travel for any given time!
I have logs of my three years of travel whilst being on board Largo, ok, you have to buy a GPS Sensor and be on the internet, but it works for a guy that is to lazy the write a log!
I also have the Cruising Log app from Android for my phone, just as a back up in case CART question Wter Explorer!
Paranoid, Me? Na! It's doable on Largo, so why not!
http://www.waterexplorer.co.uk/ and https://play.google.com/store/apps/details?id=com.gpslogs.cruisinglog
Mind you, if we all had Water Explorer, what would some chat and argue about on the forum!
Nipper