What Scott says, "There are many boat launch ramps around the state as most of the locals use trailerable boats." is true for most of the state except the Hilo area and the 100 miles on the east side of the Big Island. Hilo has one boat launch ramp
into Hilo Bay. It is ok for powerboats and ok for boats with no flying bridge but from the ramp
to the bay you must go under a bridge with clearance of less than 14 feet. While that isn't a big problem with boats with light short masts it is not the preferred method for trailer sailors who know the safe way is to put up your mast
while the boat is on the trailer and then launch.
For the past 5 years I've been trying to make that point with DLNR Boating
. Some in the bureaucracy are finally understanding it and maybe within another 5 years they may be some progress toward a solution. Depends on the politics.