I was sitting in a bar in Waikiki this past July and got invited to crew on a boat that was practicing time trials. Never raced before and I must warn you, they throw up a lot of sail in 25 knot
winds!!! Had the time of my life! I cant remember the captains name or contact info, but I would recommend going to the Ala Wai marina in Waikiki, and just walk around and talk to people, tell them you wish to crew and offer to buy the drinks. You should get plenty of offers, since many of the folks are non-pretentious liveaboards and are pretty down to earth.