Young Brothers' newest barge set off on its first working voyage yesterday afternoon loaded with Subaru Forester rental cars and military vehicles headed for training on the Big Island.

The gleaming-white Kaholo, headed for Kawaihae on the Big Island and then to Maui, is a roll-on/roll-off vessel that's covered to protect its cargo from the sun and sea spray as it travels among the Islands.

Although it's designed to navigate ocean waters, Young Brothers' latest barge bears more of a resemblance to a floating parking garage than any kind of seagoing vessel. The deck is nearly as long as a football field and about half as wide. The shipping industry nicknames it a "Ro/Ro" barge.

Young Brothers President Glenn Hong said the company spent $14 million refurbishing an older barge — the Aleutian Trader — into the new Kaholo. This is part of a $186 million capital investment that the interisland cargo specialist embarked on spending over this decade, he said.

Hong said the barge's specialized design allows the company to carry — under cover — as many as 500 cars and trucks, where in the past they could carry only about 40 cars covered.

"It's more than just this year's model," Hong said. "It's something that we've been looking at for several years."

He said most Young Brothers barges are loaded by rolling on the cargo, unlike the hoist operations that were more common in the past. He said this design is more efficient than mixing container cargo with the cars.

Yesterday, stevedores drove the cars and trucks aboard floor by floor, with a truck shuttling drivers to the Nimitz Highway side of Pier 40. They precisely parked between padded pillars. Without any parking stripes, they pulled the cars closer than a Christmas Eve shopper to make best use of the space.

Hong said the company routinely carries 700 to 1,000 vehicles each week, so Kaholo will prove useful. He said the company owns 12 barges and seven tugs, with another seven tugs at its sister operation, Hawaiian Tug & Barge. He said the next new barge is due in September, with three others coming every six months.

When the new investment push is completed, more new barges will be added, others retired, resulting in a fleet of nine barges, Hong said.

For customers buying the cars, the vehicles travel protected and get there in days instead of weeks, he said. For companies shipping them, they can move more at a time, whether it's new models or a bump in the rental fleet to handle a Neighbor Island convention.

"It increases our capacity to take cars to the Neighbor Islands in large lots," Hong said. "It improves the service considerably."

Hong said he believes the planned Super Ferry may compete for some interisland movement of cars but doesn't see a lot of overlap in business. "We believe we serve a different market," he said.

Reach Robbie Dingeman at rdingeman@honoluluadvertiser.com.