Southern Discoveries chief executive Tim Hunter, of Queenstown, said the 34m catamaran was used for scenic cruises on Milford Sound.
The boat was on the slip so a Maritime New Zealand inspector could complete its two-yearly check, including examining the propeller shaft.
The work required a ''big slip'' and ''Dunedin is one of the few places with a big slip''.
The boat was about a week into its six-week stay, he said.