You MUST have a B1B2 there is absolutely no alternative.
Let me just repeat that because Aussies are a little slow on this very important point: You MUST go to the US consulate in a capital city in Australia
and spend about $220 for a B1B2 visa. It entails an interview and you will be waiting for your 3 minute interview till nearly midday.
You can only book it in advvance (about a week), slect the earliest appointment time on the day you can go as your wait will be less.
Wear conservative nice clothes (i really mean this) and even if you are some radical beat-nick just pretend for a moment you are a normal person. Take proof of finances, money
in the bank statements, and information that ties you to living in Australia
(house, relatives, etc) If you just say "we're retired and have no plans" you may not get the visa because they may think you want to live in the US. So say: "We are buying
a boat in the USA and will cruise
USA for 6 months and then sail to Australia and be home by 2018." This gives them a framework - a pigeon hole - to put you in. Of course you can change plans anytime and you dont have to tell them, etc.
The 5 year Multiple Entry B1B2 US Visa in your passport means more than just the USA, virtually every country treats it with respect: If you have free access to the USA then you must be OK to enter the teeny-weeny country X.
So you may need a new passport before you get your B1B2. Its worth it.
Now, when you get to the USA and go boat buying
you will find its not like Australia at all! They will be appearing to rip you off in the negotiations! They are very different to the Aussie way and you need to be very very careful. Its just a cultural difference (No need for the forum red necks to start up at me for anti-americanism) Remember a few years ago when any American in Australia was an invitation to sell him shares in the Sydney
Harbour Bridge? Or an acre of the Simpson desert? Well, you are like that in the USA.
Theres two tricks they try: Being your broker. No. they are the broker of the seller, not the buyer. they will find out your budget
and 'find' the right boat for you... ie take all your money
and not show you boats for cheaper that you could have negotiated. Secondly, they wont pass an offer on to the owner unless you pay 10% deposit. That means you can only have one offer out at a time. When you are paying motel bills thats crazy.
Don't forget the Caribbean
as a place to buy a boat.