Re: Solo From Aus to Thailand via png
If your main idea is to get to Thailand you might consider going with the Sail Indonesia rally that leaves from Darwin. The longest leg is from Darwin to Timor, something like 400 miles. We found the coast of northern Queensland to either have no wind or 30 knots from the south. Once you get into Indonesia winds tend to be very light in many places so you need a reliable engine and good fuel range. The bureaucracy for entry to Indonesia is extremely complex which is why so many people go the rally since the organizers look after the paperwork.
Don't know the boat you are talking about, but it would seem to me that a 24' catamaran would not have the load carrying capacity you would want to have.
You could do it in a year for sure but you have to leave at the right time to avoid cyclones and get the right winds up the coast. As for your ability to do this trip with no sailing experience that is for you to decide. It is not the easiest trip in the world, but far from the hardest. You mention boating experience, but does this include weather knowledge and reading tropical waters?
Finished the circumnavigation in early February in Grenada. Have to work on a book project for the next several months so the boat will be waiting for next year.