A piston at the heart of TSS Earnslaw has to be custom made to replace its century-old predecessor, a job that will lead to the ''Lady of the Lake'' being towed on to the Kelvin Heights slipway.
Real Journeys announced yesterday the historic steam ship would be out of public service for a slightly longer maintenance period than anticipated, but the extension gave the operator a head start on next year's survey.
Chief executive Richard Lauder said yesterday Earnslaw was due back in service at the end of June, but the company decided to take the opportunity to complete additional work over what is a quieter time for the ship.
''We don't know about these things until we strip down the engines each year,'' he said.
''Stripping down the port-side engine this year, we found the middle of the three pistons was delaminated and therefore needed to be replaced.
''Hopefully, the things that we find we can complete within the scheduled maintenance survey, but the process to recreate this part takes longer than the time we have left, so we just decided to extend by a week or 10 days and, given that we are extending, we may as well do some of next year's work as well.''
The intention is to have Earnslaw steaming again on Lake Wakatipu in mid-July, in time for the busy school holidays.
''She is more than 100 years old and things continually need repair and we try to get as much done as we can in this planned shut, because then she has to go and do 3500 hours before the next shut,'' Mr Lauder said.
''That's quite a length of time to be in operation, 12 hours a day, 300-plus days a year, for a piece of equipment which is that complex and that old.''
