VANCOUVER -- B.C. Ferries is once again increasing its fuel surcharge -- this time as much as 18 percent on some routes.

The BC Ferries Commission has authorized BC Ferries to implement new fuel surcharges of 10.3 percent on most major routes, 17.6 percent on minor routes, and 9.2 percent on the main Horseshoe Bay-Langdale route.

The new prices -- which hike the cost for commercial vehicles by 48 cents to $5.33 per foot -- take effect August 1, 2008.

The commission says that recent fare increases implemented on April 1 are not enough to cover the skyrocketing costs of diesel fuel.

"The rise in fuel prices caught us (and many others) by surprise. Last fall we finalized our decision on new fare caps to start April 1 2008. We made that decision before the exceptional rise in marine diesel fuel prices occurred in 2008. For the current fiscal year, our ruling assumed an average price of $0.78/liter. Now, in July 2008, the revised figure is over 70 percent higher, at $1.34 a liter," the commission explained in a notice.

The commission notes that the recent carbon tax in B.C. is a factor -- albeit a minor one -- in the surcharge increase.

The ferry authority also claims it is absorbing 2.5 cents per liter of the increased cost, totaling roughly $3 million a year.

Drivers boarding the ferry also face an increase in the passenger fare from $13.00 to $14.25.