Many people use a Yamaha 9.9hp high thrust outboard on 26 -35ft catamarans. Indeed, I have used them myself for nearly 40 years, on Gypsy, Sagitta, Eclipse, Romany and Banshee. They are very reliable engines and a single central outboard works well for most people. Having said that, if you normally keep your boat in a marina (I don't) then twin outboards gives much better manouverability.

However, by turning the engine you can get close to a twin engine installation. Furthermore, because of the prop kick, turning the engine makes it much easier to leave a starboard side pontoon in reverse - otherwise you will need to spring off, or you will just bounce down the dock.

I have tried various ideas over the years, the photos here show the system I now use on my 30ft Sagitta, which seems to work the best. Pretty much self explanatory. The controls are mounted on small eyelets in the back of the cowl, the port side led to starboard and vice-versa. Pulling on a control line turns the engine as required, I rarely need to cleat the (endless) line.