Hiya, I don’t think this is the right change to make. These ferries carry foot passengers, so it’s correct that they’re tagged foot=yes. If a walking app is routing people down them, then that seems like a problem with the app; most routing apps provide an option for whether to use ferries (or toll bridges, or toll roads if driving) — and planning a walk which takes in a ferry trip in the Lakes is not unheard of either!

What app are you using?