I am currently a 4th year PhD student and have no publication so far. I switched project after 1.5 years after realizing I don't want to have a PhD in that topic.
The new project is really interesting for me. I feel much more motivated and believe I have the analytical skills to solve it. The project is composed of two parts: image analysis (A) and machine learning (B). Eventhough my advisor is very knowledgable about the first part, he is not familiar with the other part, which is actually the most important cue to solve the problem.
That results in lacking of general research guidance from him. He would points me to unfruitful direction, and when I present literature's approaches he is not interested in. A metaphor is that like doing programming big project without the knowledge of data structures. Would a co-advisor be the best solution?