Can you save an Assembly with both Solids & Surfaces in the file  I have an Assembly with a boat in it with a sail made as a surface Did a  test file as a model in a part file and it worked and the company that is making the model can open it ok.   But now I have made a compete assembly getting an error message about surfaces  Do I need to get rid of all surfaces. what about surfaces that have been used for cutting solids  and are hidden 

Does anyone know what is wrong?   

Thanks Andrew