The iconic Toronto Island ferries will begin sailing into permanent dry dock within two years, but the city's still not sure what they'll be replaced with, or how much the new fleet will cost.

Only the 107-year-old Trillium will be spared. The other four ferries — Sam McBride, Thomas Rennie, William Inglis and Ongiara — will be phased out of service starting in 2020, according to city staff.

What will become of the venerable ferries, whose average age is 70, is still up in the air, but according to Coun. Mary- Margaret McMahon, who chairs the parks and environment committee, they could wind up on the scrap heap.

The Thomas Rennie has been making the crossing between the mainland and Toronto Island since 1951. (City of Toronto)

"To scrap them is to scrap the fabric of the city," local historian Alan Skeoch said last week. "It's a sad answer. There will be a hue and cry if we do it anyway."

A survey that asks what should be done with the ferry fleet will be available online until Nov. 15 on the city's website, but visitors to a city Facebook page on the ferries' future are expressing mixed reactions to the decision to retire the boats.

Some of the visitors to a city website are urging the city to retain the 'charming' older ferries. (Facebook)

What's certain, McMahon told CBC Toronto last week, is that the four ferries must be taken out of service.

"It is going to happen, and the reason it's going to happen is that the average lifespan of a ferry is about 20 years and ours are at about 55-plus," she said. "And not to be ageist or anything, but it's time."

She said the demand to get to the Toronto Islands has grown in recent years and the old ferries can't keep up.

And some people say they'll welcome updated ferries with room for more passengers.

Island dweller Nupur Gogia rides the Ongiara to the mainland and back. It's the only ferry that also carries cars.

"When residents are being turned away mid-week, with jobs to do, errands to run, groceries to buy for families, that signals a problem with the system."

Nupur Gogia has been making the crossing regularly for 10 years. She says it's time for an updated ferry service. (Ed Middleton/CBC News)

And Biswajit Lagachu, who has captained the island ferries for about 15 years, says the current fleet is leaving a bad impression on tourists.

"When rain comes we try to protect them, but rain still gets in. You go to have good time on the island, and your clothes get wet or dirty," he said.

Public consultations will kick off in 2018. No dates or parameters for the consultations have been set, McMahon said.

Those consultations will help determine the design of the new ferries.

The Ongiara, in service since 1963. is the fleet's youngest ferry. (Lisa Xing/CBC News)

According to city figures, the current fleet has a total capacity of about 2,400 passengers per trip.

But with a total of about 1.4 million people a year wanting to make the crossing, long, snaking lineups at the Jack Layton Ferry Terminal have become routine.

"We have a lot of people waiting to get to the Toronto Islands," she said last week. "The current capacity is not sufficient for the new population of Toronto."

About 1.4 million people a year use the ferry service, all year round, a number that the current vessels are having trouble accommodating efficiently, the city says. (Marjorie Skeoch)

The new ferries will have much larger capacities, according to Matthew Cutler, a spokesperson for the city's parks, forestry and recreation department.

"We're looking at ways to be more efficient for the public, but also more efficient for the taxpayer, and ensuring that we're operating these in a cost effective and service-minded way," he said.

A naval designer in Quebec has been contracted to come up with a prototype replacement ferry. But no decisions will be made on the new fleet — or what should become of the much-loved but aging ferries that currently shuttle passengers and cars across the harbour — until after the public consultations that are expected to begin next year.

Coun. Mary-Margaret McMahon, who chairs the parks and environment committee, says the cost of the new ferries will be determined after public consultations. (Makda Ghebreslassie)

McMahon says once a design is selected, the city can begin the process of determining what the total replacement cost will be.

She says some money has already been set aside by council, and that a portion of the cost of each ticket to ride the ferries is also being set aside to help pay for the new fleet.

All four new ferries will be identical, Cutler says, to ensure replacement parts are interchangeable, which could cut down on maintenance costs.