"VIDEGRO's Ships" is a free Android application which allows you to receive AIS information directly from ships in your neighbourhood using a cheap (10-15 euro) DVB-T-DAB-FM / RTL-SDR receiver.

IMPORTANT: You need to have an OTG capable Android device and a DVB-T-DAB-FM / RTL-SDR receiver otherwise this application is useless. Search eBay / DealeXtreme for 'DVB-T-DAB-FM' to obtain one.
Before buying check the list of Supported Hardware at: http://osmocom.org/projects/sdr/wiki/rtl-sdr

Also tested with the 'RTL-SDR Blog V3 R820T2 RTL2832U 1PPM TCXO SMA Software Defined Radio' and guess what... it WORKS! You don't need to use the calibrate functionality just enter 1 as PPM-value and it works out-of-the-box!
Buy it here: https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

It is an all in one application. This means that these 3 features are combined in one:
- Find the parts per million offset (PPM) of your DVB-T-DAB-FM / RTL-SDR receiver using the build-in utility;
- Receive the AIS data directly from air;
- Plot unlimited ships data and traces without delay onto a map (or send it to another application like OpenCPN).

Please report any bugs before giving negative feedback so we can fix them as soon as possible. You can report bugs as comments on the article below or by sending an email to the developer.

The Ships development team (VIDEGRO) will not be held responsible for any legal issues that might be caused by usage or possession of the app. It is your responsibility to comply with your (local) law(s) before using Ships. Besides of that we are also not responsible for any issues like financial raised by using this app and receiving faulty incomplete and/or delayed information. We do not accept any claims of broken hardware (i.e. SDR-devices and Android devices) apparently caused by this application.

More information: http://blog.videgro.net/2017/01/ships/