Iran can still contract with rogue shippers to deliver goods but their own fleet and subsidiaries is effectively shut down.
Iran has been using many of its tankers only for storage of oil, anchored out in the Indian Ocean, waiting for buyers. Now most of those tankers are stuck and can’t offload.
Iran is very clever and could try to offload goods at sea to rogue shippers. But this new sanction really complicates Iranian sales of anything needing shipping.
I’d bet we could get a bunch of Somalis to offload all that free oil in Mogadishu...