Quote Originally Posted by technomage
Is says in the documentation not to use fixed joints? I wondered if there are not very efficient?
It says that becouse most of the time if you think you need a fixed joint you probably can do the same with a compound geometry without joints. But in your case i see fixed joints useful. As you said, the joints can eventually get broken and the two body can move apart.
But does your engines move about the hull ?

I'll have a look at using a fixed joint to connect all the items together, then I suppose it's just a question of working out the way each engine workes (e.g if I press up which direction you need to add force), any tips of that area? or is it just a question of trial and error.
Well you probably have some engines around the main body. If you add an equal force to each, you'll probably get a "forward" force.
You simply get your input from keyboard and then use some dBodyAddForce function.