Hi Jocce,
Hoovercraft? Have we a floating vacuum cleaner in the sim?
Sorry about that; I tried to resist, but the devil made me do it.
On the hovercraft, you must inflate the skirt by advancing the leftmost throttle all the way up.
If the skirt is not up, you can force a speed of only 7-8 kt over water.
Another user has reported an inability to raise the skirt. We will get back to you when we sort his problem.
You can download info.pdf, which has instructions for the hovercraft and other things, from here:
http://www.shipsim.com/ShipSimForum/index.php/topic,2886.0.html (http://www.shipsim.com/ShipSimForum/index.php/topic,2886.0.html)
Regards,
Marty