I'm using the SDK traffic "explorer" to add a carrier where I want one. Here's the step by step of what I do.
1) Create a flight in an F-18 at NAS North Island (KNZY) in San Diego.
2) When you enter the flight go to the "Tools" menu and choose "Traffic Toolbox" and then "Explorer".
3) In the "explorer" toolbox, right click and then choose "create".
4) In the create dialog click the "non-aircraft" option toward the bottom. (The vehicle list will then change)
5) From the vehicle drop-down list choose "veh_carrier01_high_detail_sm".
6) In the "Position" entry enter these coordinates: Lat (32.062722) Long (-118.151050) Alt (0) Pitch (0) Bank (0) Heading (359).
7) Click OK.

Depart North Island and fly out to sea on a heading of 220.
9) In about 5-7 minutes you will see the boat.