With the ship being 70 per cent full on average, the service would have an estimated annual revenue of $30 million and profit of between $6 million and $7 million within three years.
The study was commissioned by Midwest Ferries director Neville Johnson and its authors, Warwick Walbran and Mr Zangouropoulos, presented their findings to Whanganui district councillors this week.
"When I heard what Mr Johnson was proposing, I thought it's not going to work," Mr Zangouropoulos said.
"I've taken Neville's ideas and taken away some of the more fanciful things and reduced it down to things that can actually work.
"The point is Neville is actually on to something, which surprised me. So I've gone from a sceptic to an advocate."
Mr Johnson initially wanted multiple ferries carrying both freight and passengers but Mr Zangouropoulos said a single large, freight-only service worked best at this stage.
The thrust of the proposal was that it would save 120 net kilometres "on most main routes" and would target the highly competitive freight industry.
"Any dollar you can get is a dollar that people will fight for, so 120 kilometres is not to be sneezed a - it's actually a big saving per truck," Mr Zangouropoulos said.
Mr Walbran said 60 per cent of inter-island freight went between Auckland and Christchurch and the service would only need 50 trucks on each sailing to work.
"It's a small chunk of the total traffic and, therefore, is relatively achievable," he said.
"Once the service is established and is successful and has been operating for a few years, then we start looking at a second ship."
That second ship would carry both freight and passengers and tap into the tourism market, something Whanganui mayor Hamish McDouall urged Midwest consider as it would provide the greater economic benefit for Whanganui.
"We believe we've established a sound case that says this proposal is commercially and technically feasible in principal," Mr Zangouropoulos said.
The project would require building work at both ports, buying a dredge, fuel infrastructure and agreements between the port owners to get off the ground.
The service could be running by 2021, but Midwest Ferries will need up to $1.5 million in private funding to get the proposal to a stage where a final decision can be made.