I have checked over many years for bareboat (or other) mono hull rentals in Hawaii. As far as I can tell there aren't any. The reason given (from someone I called who had an ad in one the sailing mags some years back) was that Hawaiian waters can be semi-treacherous once outside the lee of the islands, with the inter-island channels being especially known for huge unruly seas, etc. As a side note, I'll bet most of the large cats you're finding are group day charters, with skipper. Can be kinda fun, but at $60-80 a person, ahh, not so much (at least for me). Lots of other fun water-related stuff to do including surfing, outriggers, kayaks, small boat (resort) rentals.... Have fun.