The Red Boats, both catamarans at 25.4m long by 9m wide, have been at the Kitchener St wharf and slipway for several weeks now, with the Lady of the Sounds having been almost entirely gutted in preparation for a major refit.
Caledonian Marine managing director Alasdair Morrison said the vessel had an indoor barbecue and vents installed, new galley oven, a completely rebuilt wheelhouse, as well as electronics, stairways and new bathrooms built.
A new high-pressure fire suppression system was also installed.
"There's been no time to get bored," Mr Morrison said of the numerous contractors vying for space aboard the vessel yesterday.
On return to Milford Sound, the 120-passenger Lady of the Sounds would begin a new programme of "breakfast cruises" before its standard day cruise schedule began, he said.
Barring interruption caused by bad weather, he expected both vessels would be ready to sail back to Milford by early next month.
The Red Boats fleet of five was bought from Tourism Holdings Ltd in June by Dunedin-based Skeggs Group for $17.3 million, which included some infrastructure assets ashore at Milford Sound, the Milford Deep Underwater Observatory and Blue Duck Cafe.
The Spirit of Milford is in for its two-yearly survey and general repair and maintenance on fittings and its hulls.
