Included on the guest list was Olive, Lady Hutchins (97), who is, along with her late husband, Sir Les, responsible for ensuring Earnslaw remains in operation.
The 51m 1912 Edwardian twin-screw steamer was designed by naval architect Hugh McRae and built by Dunedin’s McGregor and Company.
It was initially used to service remote sheep and cattle stations around the lake.
Eventually, in late 1969, while under the ownership of the New Zealand Railways Department, Sir Les and Lady Olive — who owned the Manapouri Doubtful Sound Tourist Company — were approached to take over the Earnslaw lease.
That was on the proviso the couple squared debts incurred by a group known as "The Boys", who ran the operation for about a year before running out of money.
The Hutchins’ company — which became Fiordland Travel, then Real Journeys and now RealNZ — eventually bought the ship in 1982 to run it as a tourist operation.
Two years later it underwent a major refit, and another is planned.
A year ago, RealNZ announced it was investigating carbon-neutral or carbon-zero fuel options.
Last week, the Otago Daily Times reported the company had narrowed those options down to either wood pellets, hydrogen or biofuel.
RealNZ chief executive Stephen England-Hall said on Tuesday the company remained committed to ensuring Earnslaw remained a twin-screw steamer, powered by steam.
"We want to make sure 100 years from now, people can still look down inside the engine room and experience what is now Victorian and Edwardian technology, hard at work.
"What produces that steam ... is something that’s up for debate."
While a new coal boiler would make Earnslaw twice as efficient and reduce emissions by a third, that would be unlikely to meet the changing sentiment towards the environment, he said.
Lady Hutchins’ grandson Ryan Hodges, now a skipper on the boat, said he hoped to hold on to the coal-fired operations as long as possible.
