Welcome to Volt Master Training
There are reguatory and professional standard that must be adhered to, ISO 13297 2020 and ISO 16135 for example, and the best way to get this training is from an experienced expert from the field, who is also actively up to date with the changes in such adynanic field.
Looking online isn't a good source of education as the information isn't current and might also not adhere to teh standards required, especially if you're looking to becoming qualified. Not only is Youtube not sufficient, in some cases it can be outright dangerous.
Keith at Volt Master training has been working in the electrical engineering industry for 54 years of which the last 40 have been in the marine industry specifically.
He is also vice chairman of the BMEEA and as such is not only familiar with the standards, he helps set the standards, and is heaviliy involved in researching and writing the code of practuice.
There isn't anyone better than Keith for your training needs.