Eyeballing the map it looks as if the width of the shipping lanes is about 10 miles.
(although I read someone else here say the actual lanes are about a mile wide)
Im no expert, but I would think it would take quite a few scuttled tankers to block traffic there.
But what would be the consequences of even deceased traffic to avoid them?
We may soon long for the days of $70 oil.
(not that the price of oil compares to the importance of Irans nuke threat)