How do I bribe ships in Freeciv?

From Freeciv 2.6.0 onwards, it is possible to bribe ships.

Below is an example of bribing a transport. Note that the transport must be empty, otherwise the bribe will fail.

It's also possible to bribe other sea units (ironclads, battleships, submarines, etc.) as long as they are not loaded:

Side note: It's also possible to bribe aircraft.