You can actually enter the ship's name into the search engine on ancestorsonboard so as long as it was after 1890 you might have some luck.
I would question how complete the original records are. My ancestors went to South Africa and from what I know I would have expected them to disembark at Durban. But these records would indicate Cape Town (although I haven't downloaded the full image yet) but a distant rellie has recently found the record at P'berg archives, Natal suggesting that they did land at Durban.
Sadly, also, some of the passengers christian names are not included making a search a bit of a hit and miss affair when there are five or six pages of possible ancestors. Not ancestorsonboards fault but it means you can only guess on age and as we all know, ages on census returns are not always accurate either. Occupation is listed once you have paid your dues but in these circumstances it could be a more costly affair than first anticipated.
From my point of view though, a lot easier than visiting Kew and looking through umpteen unindex records.
Good hunting
