This is just insane. Not only are cars themself mostly unnecessary, if the right infrastructure is provided, but SUVs also use more resources to run and be produced then small cars, without any advantage over them. So an obvious waste, which could easily be cut to reduce emissions.
Source IEA: https://www.iea.org/commentaries/suvs-are-setting-new-sales-records-each-year-and-so-are-their-emissions
Yes, theoretical hull speed is proportional to hull speed, but mondern cargo ships aren't optimized for speed - old school clippers were.
They are also more cost effective for crew - which is why you need to automate as much as possible. Electronic winches, hydraulic booms or sheets, instance access to weather, Electronic monitoring, tides and conditions forecasting and access for a harbour pilot to take over could eliminate alot, if not all of transit crew.
Will it be as fast and reliable- no. But if you can make the cost savings outweigh the drawbacks you can make a presentable business case.