1. Create a marker named "boatPos", but leave all default value.
2. Put a BLUEFOR riffleman on a shore somewhere.
3. Put a trigger in front of him, activated by BLUEFOR presence.
4. In the trigger, in the "On Act" field, enter b = "B_Assaultboat" createvehicle getmarkerpos "boatPos";
5. Start the preview and walk in the trigger.
Notice that the boat was created, but few hundred meters from the location of the marker.