Joystick method for maneuvering a marine vessel with two or more sterndrive units:
http://www.freepatentsonline.com/7467595.html
Axius:
http://www.brunswickmarine.fi/?nid=39284&lcid=1035
IPS:
http://www.volvo.com/volvopenta/finland/fi-fi/marine_leisure_engines/engines/volvo_penta_ips/volvo_penta_ips.htm Ultra Dynamics:http://www.smallships.co.uk/d/index.php?pageId=15&aid=118\\