Thank for all the replies. The diameter is probably my mistake and it would make sense that it is a 10". I live in Canada and my sailboat is currently not easily reachable (cold and snow), so I cannot verify the information just yet.
So if I am not mistaken, I understand from all your answers that my propeller might not be perfect for my engine, yet it might not be the main issue (but I will definitely get in touch with the Indigo guy).
Once the snow melts I will do some more checking according to your replies, and will post a video if I still have issues!
Thanks again everyone. This Afourians community seems really friendly and helpful
!