I'm a lifelong boater (speed boats and pontoons, not sailboats). Even if a boat rental was available, there'd be no way I'd captain a speed boat on my own off Hawaii, let alone a sail boat. The ocean is so temperamental, and the tradewinds so unpredictable that I'd only trust an experienced (and USCG certified) captain to navigate those waters. I'd never take that chance on my own. (Ditto for kayaking. When we go, it's with a tour guide who is equipped with a distress radio.)
The tradewinds are so fierce off the Hawaiian islands that twice they've contributed to deadly accidents, involving masts actually snapping on catamarans. The Kiele V sank in 2007 off the coast of Maui, killing one, and Na Hoku II was involved in an accident that killed a teen off Waikiki in 2006.
Hawaii is drop dead beautiful, but if you want to sail your own boat, I'd head to the Caribbean.
P.S. You used to be able to book a ride on America II but I've read that is now closed. However, I think Scotch Mist is still available.
