The point of attaching the limpet above the waterline is to be able to ignite the streaming fuel. It’s tricky to do. If the hole is below the waterline, it’s just pollution. The mine or mines, planted above the waterline, must accomplish two things:
One, breach the hull and get the fuel flowing through the air into the sea. T
wo, ignite the fumes to ignite the stream of fuel and start a fire that won’t go out.
This is a pretty sophisticated demolition trick, with a good likelihood of failure.
To do it successfully at all would require practicing on a dummy target in port. This was not a group of yahoos. I’m guessing IRGC Quds Force frogmen.
In my old training against big fuel tanks on land, it was always a one-two punch. One demo charge to open up the tank, and separate thermite charges to ignite the spreading fuel.
Limpet mines can only breach the outer hullof tankers and are not considered effective at penetrating the inner hull. Iran has both torpedoes and anti-ship missile which could have easiyt taken down these tankers from quite some distance away, yet you claim they would rather use an ineffective mine close up where they be could easily observed? Yeah right *rolls eyes*
Bingo bang ......