Sven,
Welcome to Cruisers Forum. Around the world there are many different approaches to sailing schools. The good news is the RYA and YA course are well thought of so you can't go wrong. Having more
training is never a bad idea if followed up with some actual experience on the
water. Time on the
water smooths out all the holes in the
training. There is the component about actually sailing a
boat and I think most people learn those skills quickly. Then there are the other skills associated.
Navigation is clearly a skill you may never truly master. Other skills related to
boat equipment,
maintenance, and
repairs are skills developed over time as well. Given we have over 96,000 posts here you can get an idea that it covers a lot of stuff. No one knows all of it but you need a good familiarity of the basics of all of it.
Your ability to charter will first be based on past experience and second by training. With a little of both you may be required to do a day of check out where you pay a
skipper to go along for a day and they decide if you really know how to manage a boat. It's a total thing. Not if you can trim the
sails but can you
anchor or operate all the
equipment and act like you are comfortable. After that it comes down to the
money. The charter companies do want the
money too.
I don't live in Sydney so I can't suggest a good
school, but my normal
advice is go to the
school and meet the actual instructor that would teach your class first. You will do better if you can communicate well with the instructor. No matter how good the school is it's only one instructor that matters to you. You might try and find the better one if they several.