Drust-etc - my thoughts exactly.
sunfish - the Iranian boat (sorry - ship) was in EU waters in defiance of EU sanctions when it was detained. Expecting to sail through unchallenged in defiance of said members states sanctions is somewhat dumb.
The uk flagged tanker on the other hand was in international waters apparently. It’ll be interesting to see what international rules/regs it had broken. No proof has been forthcoming just yet.
If we’re into analogies-
It’s like me telling you that you aren't allowed to walk through my property (or the property of my neighbours) en route to so and so’s party carrying beer, and then being annoyed when you do and then get detained. I then offer to release you, providing that you don't take your beer to so and so’s house.
You then threaten to detain a member of my family. You attempt to do so on a public highway (i,e not on your property) but get chased away by their older brother, and a few days later, you try the same again and succeed. Again-not on your property, with no proof forthcoming yet of any wrongdoing.