For Android, you have MarineSecurity with MarineSecurityMap in complement.
The first have 2 features:
1- Anchor alarm when you are on board
2- Watching against the theft when you are not on board. It sends you SMS message on an other phone with location when the boat moves.
The second, MarineSecurityMap, converts the SMS messages received, in points and traces on a google map view.
Vous can have more info here Marinesecurity : News
or here Android Market