In this Honolulu HPR interview from January 20, 2009, with HSF it mentions "the Alakai has shuttled over 200,000 passengers in the past 9 months, half of those being repeat riders." That is about mid-April 2008 thru mid-January 2009. Early-mid-April was about when the Alakai came back from it's last drydock.
In this Pacific Business News article from August 20, 2008, HSF announced "The Superferry has transported 125,000 passengers on more than 400 voyages since its launch last year." That is about mid-December 2007 thru mid-late-August 2008, or about 8 months. There was relatively little ridership in Dec.'07 thru March '08, much of it very low ridership in the winter and no ridership in March during drydock, so most of the 125,000 happened during the 5 months of April thru August 2008. That would have been at a rate of about 20,000 to 25,000 passengers per month.
From the above two points of data it can be estimated that for the 5 months of Sept. '08 thru Jan. '09 the Superferry transported about 75,000 passengers, or an average of about 15,000 passengers per month. This would be a 20 to 40% decline in ridership per month from the first 5 months after the last drydock to the second 5 months after the last drydock up through last month. So far, this dramatic decline in demand for HSF's services over the past 5 months has not been reported in the media.
But, what I really want to compare is HSF's monthly ridership to that of the local interisland airlines. Go! Airlines carries between 50,000 and 60,000+ people interisland per month. Hawaiian Airlines carries between 630,000 and 640,000 people interisland per month. So, Go! Airlines transports about 4 times as many passengers as does HSF, and Hawaiian transports about 10 times as many passengers as Go!, and Hawaiian transports 40 times as many passengers as HSF. In addition to this will be Mokulele Air which entered the interisland jet market in February '09 and who's numbers we don't have yet. No doubt Mokulele Air will put further pressure on the weakest competitor in this group.
After Aloha Airlines fell out of the market and it's market share was absorbed, Hawaiian and Go! numbers have remained relatively stable, but during the past 5 months, HSF's numbers have fallen 20 to 40%. So I am wondering, where is the convenience, necessity, and demand that Market Scope, Enterprise Honolulu, the Consumer Advocate, and the PUC spoke of in 2004?