THE son of a German wartime submariner has made an emotional trip to Swanage to place a wreath at sea where his father died 70 years ago.

Ralf Peter Spalt 's dad, Alfred, was one of 48 German submariners killed on the experimental U-480 U-boat, which is widely acknowledged as one of the first 'stealth' submarines in naval history.

The hull of the 769-tonne German vessel had a special rubber coating, making it difficult to be detected by Royal Navy sonar.

Mr Spalt took a boat out from Swanage Pier, along with friend and town resident Martin Jones, and laid a wreath at the approximate spot of the World War II wreck.

He also dropped a specially-made plaque, in memory of his father and the other crew men who perished on the U-boat, into the depths. U-480 was lost with all hands.

Mr Spalt told the Daily Echo: "It would have been my father's 99th birthday on Monday. Today was an emotional day for me. I felt this was something I had to do."

The U-boat, which operated in the English Channel towards the end of the Second World War, sunk four Allied ships - with the combined loss of 80 lives.

The Royal Canadian Navy corvette HMCS Alberni, the Royal Navy minesweeper HMS Loyalty and the British merchant ships Fort Yale and Orminster were all destroyed by U-480.

After leaving its Norwegian base on January 6, 1945, on its third combat mission, U-480 was never heard of again.

It wasn't until 1997, when recreational divers discovered a wreck about 20 km off the Swanage coast, that her fate became known.

Research later suggested U-480 had fallen victim to a secret minefield sometime between January 29 and February 20, 1945.

Mr Spalt said: "I let the plaque down as close to the wreck as I could."