Hello,
The issue of
certification of competence for
insurance is not as clear as many people think. Many companies do not require any certificate and will not even give a cheaper rate if you have one, but this is not always the case.
Boat charters do require a certificate of
training (in
Europe, usually
ICC, which can be obtained directly with a RYA Day Skipper).
You are right that it is possible to learn a lot on your own. And if you are a self learner, you can save good
money by doing it. Just make sure that you cover what is actually covered on for example RYA's courses.
However, I would not say that a online day
skipper (RYA) is not worth doing. The fact that it is online does not mean that it is easy. There is quite a lot of
work to be done (chartwork, reading, etc) that may not be straightforward for beginners. To complete the Day
Skipper, it is also necessary to go for the Practical Course, which usually involves 5 days aboard.
Hope this helps.
Cheers