A senior Marine official's teenage son drowned during an outing to Ho Pui Reservoir, Yuen Long, yesterday. Clive Lambourn, 18, was standing on the dam's ledge playing with a remote-controlled boat. He disappeared when trying to retrieve the boat from the reservoir. His father, John, a senior officer with the Marine Department's Airport and Port Co-ordination Section, was walking the dog at the time. The family lives in Yuen Long. A woman passer-by was the first to raise the alarm at about 5.30 pm. Mr Lambourn then returned to find the ledge empty and called the emergency services. Fire Services Department divers battled for two hours before finding him. The youth was taken by ambulance to Pok Oi Hospital but doctors were unable to revive him.