The man who has gone missing off the waters of Changi on Sunday afternoon is a student at SIM Global Education.

He had gone out to sea with a paddle board, and was with a group of windsurfers from his school. All of them belong to the SIM Windsurfing Club, which often trains at the Constant Wind Sailing School and Sea Sports Centre at the National Service Resort & Country Club (NSRCC) in Changi.

Mr Ho Kah Soon, director of the sea sports centre, said there was no official training when the group went on Sunday. Constant Wind requires all users renting out paddle boards to put on life vests, but the student was not using a board from the centre.

It activated three safety boats, along with one from Singapore Polytechnic and one from Singapore Sailing Federation, after learning that the student went missing.

They searched from 2pm to 7pm, from the coastal area near NSRCC all the way to Changi Naval Base, before the Maritime Port Authority took over.

"We usually warn our users not to stray beyond 800m to 1km off the beach when using paddle boards," said Mr Ho.

"We saw a bit of a storm at around 1pm in this area, but don't know if it was in the vicinity of the incident."

There are two launch sites in the area near the NSRCC beach. One is at Constant Wind and the other is 100m away.

Paddle boards can be used either standing up with a paddle or sitting down. It is a simple activity that requires no training, said Mr Ho.