The problem with Offshore vessels on even relative short term charter in Australia was that the Union (MUA) insisted on all crews (incl. Master and Ch.Eng) being Aussies.
This was taken to such extremes that tugs making tows to Oz actually handed over tow in international waters to avoid calling at any ports there.
It was a well known fact that when such boats returned to Singapore after 3+ Mths. they were in bad condition and in need of major repair and overhaul. (Not to mention removing all the “MUA, Here to Stay”-stickers plastered everywhere)
Not much incentive for the Aussie crews to do much maintenance, when they knew that they would only be on the boat for a few weeks/months.
PS> Some Owners kept their own Master and/or Ch.Eng. on board, even if there were also a MUA Master/Ch.Eng. (Some flag states do not allow foreign Masters)
How that would pan out in Court in case of an accident is not know. (I think??)