Heavy oil is almost a waste byproduct of oil refinery, could be found anywhere and quite cheap: 500$ per tonne, 500$ per 40GJ of energy.

Pretty sure electric ships are not coming anywhere near long haul shipping. However for anything close to shore - it's a real future: tugboats, bunkers, tourist boats etc.

If the demand for other oil products starts to drop due to EV prevalence, there might be less byproducts.