KEYSTONE — Lawmakers, state and local dignitaries Friday took a test drive on Steilacoom II — a ferry on loan from Pierce County and the vessel that could be the blueprint for the next addition to the Washington State Ferries fleet.

Suspended over an open-air car deck, people riding in the enclosed passenger cabin Friday afternoon got a bumpy ride across the often rough Admiralty Inlet.

“I think it’s very stable,” said Senate Transportation Committee Chairwoman Mary Margaret Haugen as she left the Steilacoom II. “It’s a little rocky. I like that in a boat.”

Haugen, whose position in the Legislature gives her a lot of say in the funding of State Ferries projects, said she has good sea legs. Other passengers might feel uncomfortable during rough crossings, the Camano Island Democrat said.

The 299-passenger, 54-car Pierce County vessel started ferrying walk-on commuters Friday night between Keystone and Port Townsend. The ferry was scheduled to begin hauling cars as well as passengers today across the inlet between Whidbey Island and the Olympic Peninsula.

The Steilacoom II didn’t quite have that new-car smell Friday afternoon when State Ferries offered dignitaries and the media a chance to ride her before she was put into service. Still, her walls gleamed, the comfortable charcoal seats shone and the bathrooms were clean. Outside, rain washed her decks, and cloudy skies blocked views of Whidbey and the peninsula.

The loaner ferry should buy the state agency some time to build at least one $20 million ferry to replace the four aging steel-electric class ferries that were pulled from service because of hull corrosion. No cars have been ferried directly between Keystone and Port Townsend since Nov. 20.

The Steilacoom II wasn’t designed for the relatively open-sea crossing of Admiralty Inlet, where some of Puget Sound’s strongest currents flow. Storms have canceled the state-owned passenger-only ferry Snohomish and in the past eight days, high swells twice sent water into the high-speed vessel’s passenger compartment. The advantage of the Steilacoom’s design is its swallow draft can be piloted in the shallow Keystone Harbor, where low tides have canceled sailings of other ferries, State Ferries officials say.

“We need reliability,” Secretary of Transportation Paula Hammond said.

If State Ferries decided to build two Steilacoom-type vessels, the second could be launched by October 2009, Hammond said.

But if state officials select another design, possibly one used by a Washington shipbuilder for a ferry system on the East Coast, it wouldn’t be ready until May 2010, Hammond said.

Although the Steilacoom II has some limitations, the Coast Guard has certified her seaworthy for the Keystone route and certified her for heavier trucks than it had initially. The ferry can hold up to four 80,000-pound semi-tractors with trailers, said Mike LaCroix, a State Ferries senior port engineer. However, if four large semis were loaded, fewer of the smaller delivery-type trucks and passenger cars would be allowed on board at the same time, he said.

Because of the Steilacoom II’s lower “freeboard,” the distance between the water and the deck when a ship is loaded, the agency outfitted the loaner vessel with a device that measures the boat’s draft, LaCroix said. The captain can watch that device to ensure the ferry is safely loaded, he said.

It is concerns over the Steilacoom II’s inability to travel in higher seas, compared to large ferries that can, that has Rep. Barbara Bailey, R-Oak Harbor, and Rep. Norma Smith, D-Clinton, saying they don’t think the Steilacoom II design will work for the second and third vessels needed to replace the steel-electric ferries.

Both Smith — who represents the 10th Legislative District with Haugen — and Bailey said they want State Ferries to find another design that will suit the route and give commuters a predictable schedule.

* Marta Murvosh can be reached at 360-416-2149 or .