A total of more than £7m is being spent on its restoration, but even with the latest £3.2m cash boost, the SS Nomadic will not be completed in time to capitalise on next year's Titanic centenary celebrations.
It had been hoped that the 100-year-old steamer - the last of the White Star Line vessels which was used to ferry passengers to the Titanic at Cherbourg ahead of its ill-fated maiden voyage - could be open for business when thousands of tourists descend on Belfast for next year's anniversary.
However, as the clock ticks down towards April 2012, concerns have been raised that officials may have missed the boat in terms of maximising the opportunity.
Major work on a new bridge and upper deck superstructure is due for completion next March, but interior refurbishment, which will include a museum and a gift shop, is not expected to be finished until the end of June. This means much of what could be a major tourist attraction will be off-limits for curious visitors.
Despite the disappointment of narrowly missing the April 10 deadline, Nomadic Charitable Trust chairman Denis Rooney has insisted it is not a big deal.
"It is not critical to us," he said. "This is a stand-alone tourist attraction and is not dependent on the centenary of the Titanic.
"The fact that it has come a bit later is not a bad thing actually because it means that there will be an extra celebration after all the major celebrations around the Titanic signature project later in the year."
"I think we have done very well. Heritage work of a similar scale usually takes much longer. This has been five years and fund-raising over £7m in the current climate has been done in a reasonably quick time."
The Nomadic was saved from destruction in 2006 when the Department for Social Development bought it and had it returned to Belfast from France.
The Heritage Lottery Fund has confirmed it has awarded a £3.25m grant for the project.
The restoration will see the SS Nomadic returned to its original condition to house an education space for schoolchildren.
Meanwhile, Social Development Minister Nelson McCausland said he had provisionally earmarked a contribution of up to £1m from his department.
"It is recognised that the project will attract new and additional visitors to Northern Ireland, Belfast and Titanic Quarter in particular by offering a rich visitor attraction," he said.
SS Nomadic was purpose-built by Harland and Wolff in 1910/11 as the 1st and 2nd class passenger tender to the Olympic and Titanic. Designed under the guidance of naval architect Thomas Andrews, the steamer is the last remaining ship of the White Star Line. She saw out the end of the last century as a floating restaurant beside the Eiffel Tower in Paris and was saved from being scrapped in 2006.