First you see it, then you don't.

The controversial wreck of the American bomb ship SS Richard Montgomery off the coast of the Isle of Sheppey disappeared from view today as an exceptionally high tide washed over its three masts.

Peter Ward, who was watching from a balcony at The Leas, Minster, said: "I couldn't believe it. I looked out to sea and suddenly realised something was missing.

"After all these years, the wreck was no longer visible. There was just the marking buoy. I thought someone had at long last moved the ship."

But the answer was in science.

Today at 1.24pm was a spring tide when the Sun, Earth and moon were all in line. It meant more gravitational forces than usual were pulling at the Earth's seas.

Today's tide measured 5.91 metres but the next tide, due at 1.52am tomorrow morning, will be even higher at 6.08 metres.

Today the water at Sheerness was so high it began lapping over the top of Neptune's Jetty.

Mr Ward, who is known on the Island as Mr Bumper Car because he has a collection of 70 fairground dodgems, admitted: "It would be a bit sad if we lost our wreck. People come from miles around to look at it. It's like going to Trafalgar Square in London and finding Nelson's Column had gone.

"If it is permanent then we will have to get the mermaid mural repainted."

Artist Dean Tweedy painted a miserable mermaid on the wall of an amusement arcade with a picture of the wreck and the words "Welcome to Sheerness. You'll have a blast."

The Richard Montgomery liberty ship was carrying 1,400 tonnes of munitions from America to Britain for the Second World War when it hit a sandbank and sank on August 20, 1944, 1.5 miles off the coast of Sheerness and visible from Southend.

Some of the explosives were taken off but many tonnes still remain.

Experts say the bombs are no longer a threat but residents on the Island still live in fear that there could be a tsunami if it ever blows up.

The safety of the wreck is monitored by Peel Ports which runs the Port of Sheerness.

As the tide dropped, the masts became visible again around 4.30pm.