Shane, its probably worth while going out to Changi sailing club. I went out there last weekend, found out about hiring saling boats (Lasers, 420's, Cat's, J24's, Maxi 77's), costings, regulations etc..
If you want to be a crew member, go out there and talk to people - there is a large regatta coming up in December and crew members should be in demand. Unfortunately, foreign boat licenses are not accepted in Singapore - so if you want to hire a larger boat with an engine you'll need a Singaporean license.
Have a look at
http://www.sailing.org.sg/