There's a spot at the top of the hill in Meadowbank where you have to make a choice. Turn right and the station is a few minutes away on the flat. Keep going down towards the water and you're walking closer to fifteen before you've even started. I know which of those gets me to work faster. I keep going down the hill anyway and I don't reckon I'm being irrational about it. A Sydney ferry commute is the slower option on that corridor and it isn't close.
Here's the size of the gap. The F3 winds down the Parramatta River past Kissing Point and Cabarita and Drummoyne and lands you at Circular Quay somewhere around the fifty minute mark, once you've added the buffer you leave yourself when the next boat is a long way off. The same front door by rail is a shorter walk and a bit over twenty five minutes to Central. Those are official trip planner numbers for a weekday morning and you should go and run your own before you trust mine. Something in that trade is worth more to people than the twenty odd minutes it costs and the arithmetic on its own has never explained why.
The rails win the clock and it is not close
Door to door on that corridor the boat takes roughly twice as long and the gap widens the further up the river you start. That's not a knock on the ferries, it's just where the river goes. The Parramatta bends all over the place, the wharves are spaced for the suburbs that grew around them and every stop between you and town costs a minute or two of berthing. A rail line goes where the surveyors put it and that is more or less straight.
Frequency is the bigger gap though. In the morning peak the T9 gives you several services an hour at Meadowbank. The F3 gives you a handful and it thins right out either side of the rush. Look up your own wharf on that same trip planner rather than taking my word for it, because headways vary enormously by route and Manly is nothing like the upper river.
The boat wants you decided before you leave the house
Here's the bit that changes how you run the whole thing. The F3 timetable is what decides your morning, not your legs. Miss the 7:12 off Meadowbank and the wait is long enough to walk back up the hill and put the kettle on.
What that does in practice is shove all your margin to the front of the trip. You have to be decided ten or fifteen minutes before you'd otherwise think about moving and there is no making any of it up between the front door and the pontoon. That's why the two commutes feel so different to run even when the totals are close and it's why people moving onto a ferry route spend the first month checking an app far more often than they expected to.
Reliability is two different questions
Is the ferry reliable in Sydney?
Transport for NSW publishes on time running for both and you can go and read it yourself. The ferry performance reports and the Sydney Trains ones both live on the same site and are refreshed as new results come in. I'd rather send you there than quote a percentage that'll be out of date by the time you read this.
The percentage isn't really the argument anyway, because the two modes fail in different shapes. Rail failure is usually small and frequent. It's three minutes here, a bit of congestion there and every so often a signal fault that takes an hour out of your afternoon. On the water it goes wrong far less often and it goes wrong completely when it does. A boat is either sailing or it isn't. So a route can post a genuinely good on time figure and still leave you much worse off on the day it lets you down.
The harbour has a limit and the rails mostly do not
Trains push through a lot. Heat brings speed restrictions, a big storm brings trees and water over the tracks and the network degrades rather than stopping. Ferries have a harder edge to them. When the swell at the Heads gets serious the F1 gets suspended outright and buses cover the route instead. That happens often enough that regular Manly commuters already have a plan for it.
The upper Parramatta River has its own version of that. Services between Rydalmere and Parramatta get replaced by buses during extreme low tides, which is a strange thing to have to organise a work day around. It's written into the timetable rather than hidden away, so at least you can see it coming. None of this is a scandal, it's just what happens when your route is made of water. The catch is that the replacement bus is slower than the boat and slower than the rail run would have been. A bad day on the ferry ends up worse than a bad day on the rails even before you count the waiting.
What a Sydney ferry commute costs against the rail fare
Every mode on Opal is cut into distance bands. Ferries get two of them, split at nine kilometres. Metro and rail get five, stretching out past sixty five kilometres, so a short hop by rail comes in under a short hop on the water while a long haul eventually overtakes it.
The discount is what catches people. Metro, rail, bus and light rail all take thirty per cent off outside the peak and all day on Fridays, weekends and public holidays. Ferries get none of it. So if your hours let you travel outside the morning and afternoon peak the rail fare drops by thirty per cent. Same again if the day you go in is the Friday. The ferry fare sits exactly where it always was. Across a year that adds up to more than the per trip difference suggests. Current numbers live on the adult Opal fares page and they move most years, so check there rather than trusting a blog post.
Two things soften it. Transfers between modes inside a single journey earn a discount off the next leg and the Manly service gets a longer transfer window than the standard hour, which is more generous than I expected when I went looking! The daily and weekly caps cover every mode together as well. If you travel enough to cap out you never feel any of this!
How does a ferry commute compare with driving?
Better than it looks, on the corridors where the water goes somewhere the road doesn't. Driving in from the lower North Shore or the northern beaches means a harbour crossing, a toll and then parking. The variance on a bad morning is enormous. A ferry has a published timetable and a seat waiting on it! Where driving beats it is the same place rail beats it. You can leave whenever you feel like leaving. If your day ends at a time you can't predict, that flexibility is worth real money.
What the ferry wins is the part of the day you remember
This is where I stop being even handed. Take the next bit as a preference rather than a finding.
Is the harbour commute time worth the extra half hour?
For me it is. Here's what you're actually buying. On most sailings you get a seat and not a seat you had to fight anybody for. You get air and a window that isn't a tunnel wall. You also get the better part of an hour where nobody can reach you, which I did not expect to value as much as I do. You can read a whole chapter! Coming down past Cabarita on a still morning with the back deck to yourself, the crossing stops feeling like the price of getting to work.
The rail version of the same trip is twenty five odd minutes standing in a vestibule with your bag between your feet and you get to the office having spent none of it on yourself. Both get you to work on time enough. I just like the version where I've had an hour to myself first. Over five years of mornings that's not a small difference. Every time I've done the sums the rails win. Every time I've asked somebody who actually swapped, they tell me they'd do it again.
How I would choose between them
If the clock is your constraint, take the rails. If somebody notices what time you get in, if there's a school drop off wedged into the middle of your morning or if being half an hour late turns into a problem for other people, the water is the wrong tool and no amount of view fixes that.
The other way round, if what you're protecting is the day rather than the clock, take the ferry and give it the margin it wants. Mostly that means giving up on aiming for one specific sailing. Naming the window you'll be leaving inside beats naming a departure you then have to chase all afternoon and I've written up how to get an alert before every ferry in the window you actually finish in if you'd rather not do that part by hand.
Before you commit either way, test the trip home rather than the trip in. Morning headways are the best a route ever looks and the evening thins out earlier on the water than it does on the rails, so the sailing that really decides whether a ferry commute works for you is the one at twenty past six on a Thursday and not the one at eight in the morning.
Give both a proper fortnight before you make the call and make sure the fortnight includes a couple of late finishes. Those are the mornings after that decide it!