I suspect it's cos Red Eagle is one of the most difficult vessels to control, so maybe the guys at VSTEP wanted people to get used to her first in 'free roam' before creating any missions.
Someone has created a mission for Red Eagle to sail from Cowes to Southampton and also Red Jet 4 to sail Southampton to Cowes. You can find it at:
http://www.shipsim.com/ShipSimForum/index.php/topic,1128.0.html
Kev