I used to visit Singapore of a semi regular basis and saw some sailing there. It's very light wind. I'd say it rarely gets over 10 kts. Sometimes more in the front of a thunderstorm. Makes SEQ look like Maui. IIRC East Coast park is where the sailing happens. I'd doubt whether it would be worth trying to chase a sail there.
I went to mana mana beach club but did not sail, take the mrt to Bedok station on the EW line then walk down the road to get there, wind is light most of the time and when I made it there there was a massive thunderstorm sitting just offshore amongst the massive amount of ships at anchor there so they would not hire
I have recently moved (6 months ago). I store my gear at Mana Mana although Water Venture is more popular with many sails rigged up most weekends (cheaper to join and store gear). My small sail is now an 8.7m and my large one an 11m. I have brought an F16 catamaran and have a lot of fun on that and don't get out windsurfing a whole lot right now.
However, while the wind is usually light, it does get up above 10knts often, you just need to be able to take advantage of this when it happens as it won't last all day. Also, I the NE monsoon is just getting going which should bring 14-20 knots as reflex says.
Thus Changi is the place for the NE and the East Coast in the "SW monsoon". The windsurfing/sailing scene is alive and well and very social. Clubs are set up to store gear with a range of facilities (swimming pools, bars, resturants etc). Very handy after rigging your gear in the heat to jump in the pool to cool off prior to launching.
I don't know about sailing but there is a nightclub called Avalon which is floating on a pontoon out in Marina Bay in front of the casino and is made out of transparent crystal and is about 5000 sq metres ... I would assume based on that the windsurfing is ok. I'm there in January to sail...
