The owners of the 117-year-old SS Glenlee hope the move will double its annual visitor numbers to 100,000.
The Clyde Maritime Trust had expected 80,000 people a year to go on board after the tall ship moved downriver from near the Scottish Exhibition and Conference Centre when the Riverside Museum opened in June 2011.
However, it notched up only 50,000 visitors – adults were charged £5 with one child admitted free, and entry for others ranged from £3 to £4.50.
That was despite the transport museum attracting more than one million visitors in its first seven months – overtaking Edinburgh Castle.
The Clyde Maritime Centre, which operates the Glenlee for the trust, said visitors to the museum had baulked at having to pay to visit the ship.
It hopes to recoup the entry fees by increased spending in the ship’s cafe and gift shop, while donations will be solicited from visitors.
Centre chairman Frank Brown said: “Visitor numbers have been lower than we would have wanted. We have had very poor weather over the last 18 months, and also did not appreciate the psychological effect of the Riverside Museum being free. People coming from a free place were hesitating when they reached the ship.”
Mr Brown said there were plans to expand the capacity of the cafe by one-third to seat 50 people, while the food and drink available would be reviewed.
He said the free admission policy would continue until at least next year, with an assessment being made in three months.
Glasgow City Council said the move was bound to attract more tourists. Its spokeswoman said: “Glasgow is famed for its free visitor attractions and I am sure the tall ship will now be on every visitor’s ‘must see’ list.”
The Glenlee underwent a £1.5 million refurbishment as part of its move to the Riverside Museum at Yorkhill Quay.
Constructed in 1896, it is one of only five Clyde-built sailing ships still afloat and the only one in the UK.
Ten years ago, the city council agreed to write off a £750,000 loan to the trust to save the vessel. A council report stated: “The centre has found it difficult in an environment where most visitor attractions are free. The result is that visitor numbers have not been sufficient.”
At the time, the centre said its losses would be turned around with the move to the museum.
Scott Taylor, chief executive of Glasgow City Marketing Bureau, said of the free admission policy: “This will ensure a great many more Glaswegians and tourists will have every opportunity to visit this wonderful museum.”
Trust chairman Duncan Cunningham said: “We are delighted to offer free entry on to the tall ship at Riverside just in time for the Easter holidays.”