The 700-tonne Stalheim had been delivering supplies for the war effort when it was holed by the blast from a magnetic mine
off Port Talbot on July 31, 1940.
Magnetic mines attached themselves to sea vessels but on land a clockwork mechanism came into force.
"The course, which really consisted of only about one day, was taken under the direction of Lieutenant Commander John Ouvry whom I have always regarded with considerable awe as he took the first magnetic mine to bits at Shoeburyness."
He was credited with helping to counter 'Hitler's Secret Weapon', a highly dangerous series of magnetic mines
, and was the first naval officer ashore with the main liberation force at Jersey, re-taking the Channel Islands from the Germans in 1945.
HMS Bronington is one of the last survivors of the Ton class of minesweepers and mine hunters which were planked in wood to avoid triggering magnetic mines
Lott in Most Dangerous Sea (1959), Soviet personnel not only trained North Koreans and supervised mine assembly, but actually laid magnetic mines off Korean coasts.
Magnetic mines, also bottom-dwellers, were set off by a ship's electrical field.
"They are much faster than ships and are effective against both acoustic and magnetic mines
, which then are actuated."
This greatly reduced the threat from magnetic mines.
It was designed as a magnetic mine for use against ships.
Atherstone is a Hunt class ship and is one of the first in the world to be made of fibre-reinforced plastic to reduce her vulnerability to magnetic mines
. She displaces 750 tonnes, is 60m long and has a crew of around 45.
HMS Bronington is one of the last survivors of the Ton class of minesweepers and minehunters which were clad in wood to avoid triggering magnetic mines