Thanks all for your answers. I think finaly to use one .40 engine. I have one question about the prop, I've seen yours model photos and there are some people with a two blades prop and another with trhee, if the three blades have diameter smaller than two, for equal performance, it's very suitable for to get an low gravity center boat, why the most models have two blades prop? I'm sorry for ignorance and my english. Best regards