 Two of her four funnels were removed , and the forward two were cut at an angle to resemble those of a German destroyer . The bow was packed with 4 @.@ 5 tons of high explosives , which were set in concrete . It was decided that the explosive charge would be timed to <unk> after the raiders had left the harbour . To prevent the Germans <unk> her away , the crew would open the ship 's <unk> before abandoning the ship . Should she become disabled or sunk before getting to the dock , four motor launches had been detailed to take off the crew and put the commandos ashore . The charge would be reset to explode after the last boat had left . 
