The main obstacle here is the energy density of those is much lower. We're talking 20-30wh/kg. So you would need about 7-8x more mass compared to a 170wh/kg battery. For ships like this (capable of 5000km), the tanks would take up most of the ship with barely any space for useful load.

Otherwise, it's not a bad idea as you could pump the pre-charged fluids in/out and even ship the fluid around with tankers; which opens up the possibility of fueling at sea. Spills would be bad. But probably better than oil as the toxic fluids dilute more easily. But it would still be a bad day for marine life. It might work for shorter ranges.

How about towing the humble battery barge? Get a new barge when in port.