By Jonathan Morris
BBC News Plymouth
Plymouth, blessed with a deep-water harbour and easy access to the western approaches, has long been recognised as a great place to build boats.
Sir Walter Raleigh first suggested the navy set up there and in 1689 the Admiralty started drawing up plans.
At its peak in the 1950s the yard employed about 40,000 people. Defence cuts mean it now employs about 4,000, and 600 more jobs are going over the next year.
But there are hopes of a bright new future for the city's maritime industry, using the same land that the navy does not need any more.
The key to this vision is 100 acres of disused naval land called the South Yard.
Supporters, including local MPs and the university, estimate it could become a marine science park, supporting up to 3,000 highly-skilled jobs.
"It is becoming increasingly obvious that Plymouth is a global centre of excellence in coastal marine science," says Plymouth MP Linda Gilroy.
"We are on the front foot."
Part of her confidence stems from the strength of the city's existing marine science teaching and research institutions, with 450 marine scientists and 1,200 undergraduates.
Marine industry is worth £244m a year, 6.7% of Plymouth economic output
There are 6,933 people employed in the industry, 6.4% of Plymouth employment
Plymouth has 400 marine companies, the biggest cluster of marine industries in the region
The university's Marine Institute is a key player in the science park vision.
Plymouth is also home to the Plymouth Marine Laboratory, the Marine Biological Association, the National Marine Aquarium, the Diving Diseases Research Centre and the Sir Alister Hardy Foundation for Ocean Science.
"This is not a pipe dream, it has been done elsewhere in Europe and we believe it is possible here at South Yard," says Professor Laurence Mee, director of the university's Marine Institute.
"There's a recognition that we need to give fresh impetus to our maritime economy."
Supporters are also hoping the site will also be home to the proposed UK Marine Management Organisation (MMO), which will be responsible for the development and protection of the marine and coastal environment.
Ms Gilroy says that if the government names Plymouth as the base for the MMO, it will kick-start the development of the science park.
However, first the navy has to release the land at South Yard and the financing of the park is relying on funds from the government from the sale of other surplus land at the naval base.
"The science park is worth exploring, but whether it will be successful I don't know," says Professor Peter Gripaios of Plymouth Business School.
If the science park is not successful the prospects for the marine industry in Plymouth do not look as positive.
There have been encouraging signs at luxury boat firm Princess Yachts, which is looking forward to significant expansion under a new owner.
The dockyard is shedding 600 jobs over the next year
But the winding down of the dockyard, which still employs the vast majority of people in the city's marine industry, would be devastating for the city if there is nothing to take its place.
"The prospects for Plymouth are not looking fantastic," says Professor Gripaios.
"It will be very difficult to replace the navy and the dockyard because Plymouth is so far west."
City MP Gary Streeter agrees.
"I am not a betting man but if I were I would stake my mortgage on submarines and frigates going from the naval base," he says.
"The issue us what we will do with the real estate.
"Unlike the South East, there is not the same kind of substitute activity.
"We are 230 miles from London and we shall need substantial government help."
Adam Corney, executive director of Marine South West, which trains people in the marine industries, says that overall the industry is in good health.
"We are on the cusp of something quite huge over the next year or 18 months," he says..
"We have every reason to be optimistic."