Civic leaders are hoping the Labour peer, who became High Steward in 2013, will help drum up the £2.5m extra money Hull Council needs towards the £27.4m project.
Lord Mandelson was taken on the route tourists one day will follow from the Maritime Museum, through Queen’s Gardens to the old dry docks, which will be home to the country’s last sidewinder trawler and a new visitor centre.
Taking in the surroundings - some of the quirkiest architecture can be found along the river Hull - he remarked on an extraordinary Gothic warehouse, adding: “Partly what this is about is rediscovering and bringing out the character of the city.”
Asked what he could do for Hull, he said: “I’m here to bring sharp elbows,” adding: “I can be a megaphone...a witness, tell people what’s going on so this place is even more firmly put on the map than in City of Culture - and that was some achievement I can tell you.”
The former European Union Trade Commissioner - who warned that the Brexit deal was a “lose lose” for the country - said he was also “keen to pursue” proposals for a £50m cruise terminal on the Humber.
He said: “It is a big multiplier for the city. If you think of all the support services that would be needed for so many people coming in and all that they will need to buy.
“It used to be a trading, fishing, shipping city, now it’s going to become an energy maritime city, but it needs more people coming through.”
The Heritage Lottery Fund is putting £15m into the maritime project, which aims to attract an extra 300,000 visitors a year.
Last month a new charitable trust, Hull Maritime Foundation, was registered which aims to raise the additional £2.5m.
Architects have already been appointed for the work on the Maritime Museum, which is due to close at the end of 2020 for 12 months.
The revamp will include a new central atrium and more than 8,000 square foot of new gallery space. For the first time people will be able to go up into one of the cupolas for sdtunning views across the city.