With an eye on the tourist attraction's long-term future, owner Real Journeys will haul the 330-tonne, 51m-long vessel ashore tomorrow morning for six weeks of routine maintenance work.
Chief executive Richard Lauder said the company was focused on future-proofing the vessel.
''She's weathered the last 100 years really well, but we want to ensure she lasts another 100 years.''
A section of TSS Earnslaw's hull plating and framing around the propeller area would be replaced, as would the piston cylinders and rings on both main engines.
Consultants from Christchurch would carry out spot testing on its hull and framing, along with sonar scans of any areas requiring closer attention.
The 102-year-old steamship is not the only piece of kit needing care and attention.
The slipway has been in use since 1922, while the engine used to winch the vessel ashore is 122 years old.
Project engineer Drew Bryant said about 40% of the slipway's rotting timber supports had been replaced with concrete and steel, with the remainder to be replaced in the next few years.
About 20 wilding pine trees around the slipway and engine shed were felled earlier this year to minimise fire risk.
TSS Earnslaw will leave its berth at Steamer Wharf about 8am tomorrow.
Under the guidance of two other vessels, three divers and about 20 staff, it will be winched up the 150m slipway from about 10am.
Other Real Journeys vessels will continue to take visitors to Walter Peak until TSS Earnslaw returns to service on June 29.
