Liz Truss today said she would continue with plans to replace the Royal Yacht - but would try and seek funding from businesses.
The Foreign Secretary, vying to become the next Prime Minister, also said she regretted comments she made as a teenager in which she called for the monarchy to be scrapped.
The new Royal Yacht - which backers say would be a "floating embassy" promoting British interests around the world - could cost up to £250 million.
Opponents have branded it a "vanity project" and called for it to be scrapped.
The Tory leadership candidate told reporters in Peterborough: "I do support the idea of promoting our trade around the world.
"What I would be seeking is to get investment into a yacht, looking to the private sector to assist with that to make it financially viable."
Ms Truss did not specify how much of the project would be funded from the public purse.
She added: "Global Britain is a very effective and successful brand and I'm proud of the role that I've played as trade secretary and Foreign Secretary in leading on the world stage."
It comes after a resurfaced video showed her as a 19-year-old calling for the royal family to be abolished.
Speaking at a Lib Dem conference in 1994 the then-19-year-old, who headed the Liberal Democrat group at Oxford University before changing her political stripes, said she agreed with Paddy Ashdown, the former Lib Dem leader, who said the institution should be axed.
Ms Truss told the gathering in Brighton: "I agree with Paddy Ashdown when he said: 'Everybody in Britain should have the chance to be a somebody'.
"But only one family can provide the head of the state. We Liberal Democrats believe in opportunity for all.
"We do not believe people are born to rule.'"
But 28 years later, she's had a change of heart.
The cabinet member said today it was a "mistake" that she regretted "almost immediately".
Asked when she realised she did not want to scrap the monarchy, she stated: "Almost immediately after I'd made that speech.
"I was a teenager at the time and I do believe that people who never change their mind on anything and think the same at 16 as they do at 46 are, well, first of all they're not normal people like I am, and secondly, you know, I've got the ability to learn from mistakes I've made, things that I've done that are wrong and move on."
