as a Mechanical engineer working in marine field thought, electrical circuit diagram would not be beneficial for me that is for only ETO to troubleshooting also electrical circuit stuff would be difficult to understand, but these package proved me wrong,i suggest all marine engineer to study electrical circuit as well as well.once you start here it is so easily described that you will go with flow and without feeling you will finish the course and i am sure you will have significance amount of knowledge compare to prior the course.