I think the general consensus is that if you downgraded a roadway from any to Ferry that it will be less preferred than most other routes, even routes which may take longer. But I have to contend that with ferries they're either ferrying you across the water or you're sitting still. Waze doesn't take any of the sitting into account, and in fact doesn't take into account the actual crossing time. I've got another UR stating they were taken to the Seattle/Bremerton ferry to get from Seattle to Portland. That's over 150 miles to the south, yet Waze wants them to take an hour ferry ride to the west and drive from there. To go south from there you either go across a toll bridge or head out to roads that are one lane each direction and many spots that the speed limit is bellow 45 mph.https://www.waze.com/editor/?zoom=5&lat ... 41&env=usa
But lets look at who you can assume would and wouldn't want to ride a ferry. Those that would want to ride a ferry would likely seek that route out. Yet those that likely wouldn't want to ride the ferry (the majority of drivers honestly) would not appreciate being led downtown Seattle to sit in line, pay $10 per person in their vehicle, to ride across an hour trip that Waze thinks takes 10 minutes, only to find they now have a longer journey than if they just drove south (or vice versa).
Basically if the ferry's route is broken by design, why do we insist on keeping it set to a priority road type?