I have subscribed to ancestry for years - if you have ancestors from England - very worthwhile (imo) - I don't find it expensive for what I get. Many libraries and family history centres have access at no charge to members - so its worth checking out any nearby places
I've found I always get an answer from any organisations I contact - some are extremely helpful, so I would certainly email a request as to whether employee records for the ferries are available. In past times many govt organisations had their own archives - I think most now use the state archives or national archives in Canberra (for the feds).
If you live in Sydney you can visit the archives - out near penrith - I visited from Qld a couple of years ago - mainly looking for wills and inquests - but much more there if you live close enough for regular visits.
You should be able to get information on his merchant navy service if you don't currently have it - try checking with the war memorial to find out where to look - or some of their links might lead you in the right direction
The national archives will always answer queries - they charge for copies of files but answer queries free of charge