Very very close to the airport actually. They are at Changi Sailing Club which is at Changi Village.

Web address is: http://www.csc.org.sg/

I am sure you will bump into Scott and Alice who can help you out (they are the cat dealers here). Otherwise it is a great spot in Singapore, nice and quiet and a good vista.

I normally sail the moth from a different club, but if you need assistance in Singapore give me a PM and i can help you out.