[trophyhead]

You can, but you may not get the results you're looking for.

APRS is a line-of sight signal. In a balloon, you might be heard by transmitters 200 miles or so away. On a boat, I'd expect that range to drop to 50 or less. So if you're out at sea, it's unlikely you'd be heard when you're much outside the view of land.

WSPR has a very long range, but the density of information transmitted is very low. Each transmissison takes about 2 minutes and the tx rate is around 5 baud (not 5kb...5 baud!). The protocol was developed to test the range of ham radio antennae and it doesn't give you much more than the transmission voltage and the 'maidenhead' coordinates (which will give your location within a roughly 80 mile box depending on your latitude).

If that rough estimate of your position is good enough, WSPR may be useful to you for tracking a boat. Some balloon trackers also transmit a secondary signal under a different callsign with some more advanced telemetry information, such as altitude, speed, more granular position within a 2 or 3 mile box.

Also, you'll need an antenna of some length. My balloons transmit on the 20m bands, which means it has a 17 foot antenna both above and below the tracker constituting a half dipole (it's 36 gauge magnet wire so weights almost nothing. If your boats are big enough to cross oceans, you can likely mount them in a way where you'd be heard.