Standing by Kallang River one Saturday morning, full-time national serviceman Kok Yao Xiang, 20, cut a dashing figure in his uniform.

His fresh demeanour belied the fact that he had been up since 4am to prepare for a rehearsal of the 21-gun salute, ahead of the first preview for the National Day Parade (NDP) on July 22.

During the NDP on Aug 9, four howitzer guns on board the Mobility 3rd Generation (M3G) military raft will fire 21 times in salute to the President as a military honour.

"I feel very lucky to be chosen for the NDP," said Corporal First Class (CFC) Kok.

There are more than 60 people who work behind the scenes to ensure the presidential gun salute goes smoothly.

CFC Kok is part of the gun detachment crew tasked with loading and firing the 25-pounder blanks.

The M3G raft is operated by combat engineers to bring the gun salute closer to the audience.

To mark NS50, the 50th year of national service in Singapore, the first round from each of the four guns on board the M3G raft will be fired by operationally ready national servicemen.

The rest of the shots will be fired by full-time national servicemen.

It will be Third Sergeant (NS) Lim Yew Aik's first time taking part in the presidential gun salute component. He had taken part in the NDP twice previously - in a marching contingent and as a marshal.

"I've always wanted to fire the gun," said the 42-year-old traffic light system maintenance engineer.

"My two sons, aged eight and six, are also excited. They told me they want to see me on TV."