Normally they’re well offshore where little craft like this wouldn’t venture, right?
In narrow water ways, there is no "well offshore." Our warships will be threading their way civilian shipping, including trading, fishing and pleasure vessels of all kinds, a lot off it making short trips along the Gulf coast, or across it. If the Navy knows in advance when, and where,the Iranians will attack, I don't doubt that our aircraft and helicopters could easily destroy Iranian fast boats by the hundred. But I also think it is preposterous to think that the lack of guns on our warships isn't a big deal, because we have enough helicopters to give all of our warships 360° protection, 24-7.