Aloha All!
When choosing a charter boat use caution when choosing a six pack. Choose an 8-12 pack with only six people on board.
In the US, six packs are NOT subject to the manditory twice a year Coast Guard inspections. This means that the mechanical (fuel lines and lights etc), safety equiptment, and general safety practices of the crew might not be fully up to standards. In the U.S. any boat larger then a six pack must have a safety inspection and a hull inspection every year. And if your inspecton expires, the fine is $10,000 dollars a day.:naughty So I can tell you, no one here in Hawaii misses the inspection date.
I have Captained on both six packs and inspected vessels here in Hawaii, and I can tell you that many six packs are safe enough, but EVERY inspected vessel is properly maintained for safety, at least twice a year.
Inspected vessels must maintain records of safety drills, repairs, and inspections, along with having crew and captain safety drills every month, all deck lines and safety lines (ropes) must pass code, all guages and wiring must work properly, all engine vents and emergency closers must function, all fuel lines and pump hoses must be kept updated. All automatic and manual fire extinguishers must be tested and taged. And the list goes on for three or more hours of inspection by the Coast Guard.
While I dislike diving on a "cattle boat", I would choose an 8-12 person vessel where the guide to diver ratio is no more than 6 to 1. I recomend diving on a privately owned charter boat where the owners are the Captain and guide. And more than one captain on board never hurt anyone.
Just food for thought.
Matthew J D'Avella, Kona Hawaii