There are a couple of ways,
1. In a shipping container (but the boat's dimensions need to suit)
2. RoRo - Roll on Roll off. This is how my boat will be transported - on its trailer, rolled onto a car carrier in Baltimore and rolled off in Sydney
3. There are also vessels made to specifically transport large boats, whereby the shipping vessel takes on water, the boat is 'sailed' in and then the water is then pumped out of the shipping vessel and the boat is strapped down on a cradle.
The Grady market in Aus is relatively immature, so there are limited pre-loved Grady's to buy. We have a couple of dealers that will sell you a new one though. The US is really the only option for a pre-loved Grady. You may find it hard to believe, but its still economically viable to purchase and ship a Grady from the US. There are some good deals at the moment.
Its a lot of work (late nights and early mornings) and stress, but hopefully it will pay off when my sweet 228 arrives!
Anyway, apologies for hijacking the thread. That's enough from me.