A few years back I faced this issue with a 110v US boat in Australia
I bit the bullet and paid the extra for a top quality isolation transformer. It sits in the cockpit
on a piece of wood and connects to the boat with a standard Marinco pigtail. It connects to shore via a regular hardware
store extension cord. The isolation factor gives me necessary safety
from oddball power surges that you get in far flung places. Everything works just fine be it microwave, drill, sander, computer, hell even the toaster.
I recommend paying the extra for a quality isolation transformer. All you need is a simple household plug
adapter and you can use this unit in any 220v - 240v country. Mine has never overheated and doesn't hum or buzz. My record
24/7 usage was 2 months without a single
hiccup. This is the transformer.
Step down transformer australia