NANTUCKET - Signaling an abrupt shift in direction on the ambitious new service model, Steamship Authority general manager Armand Tiberio said yesterday that the boat line will ax two key elements of the model, including the controversial scheme to replace all three ferries on the Nantucket run with one multipurpose high-speed ferry.

"If we are not going to be able to use technology - if the position is that a high-speed vessel is not okay, then so be it," Mr. Tiberio said.

Mr. Tiberio also said the plan to shift freight traffic onto barges will be abandoned.

"Barging - I don't think it's going to work - we need to take a look at some other options. I don't believe that over the long haul freight on a barge is the answer," he said. "We're pretty much back to square one on the issue of freight," he added.

Mr. Tiberio offered no detailed explanation for the decision.

His comments came during the regular monthly boat line board meeting held on Nantucket yesterday morning.

The meeting was marked by a tactical retreat of sorts on the controversial Nantucket portion of the service model.

Last month, 800 people turned out for a public hearing on Nantucket to express their unanimous objection to the service model and the conceptual plan to replace all three ferries on the Nantucket run with a single multipurpose high-speed ferry.

Three days later, SSA board chairman J.B. Riggs Parker called the Nantucket mandate uninformed, and he and Falmouth member Edward DeWitt vowed to press ahead with the service model.

Yesterday Mr. DeWitt had something different to say.

"We heard you loud and clear," he told Nantucket governor Grace Grossman.

"It's not me, it's Nantucket," Mrs. Grossman shot back.

"When I say you, I mean Nantucket. There is not going to be a single three-tiered high-speed ferry to Nantucket," Mr. DeWitt said. "I have always had some concerns about the three-tiered ferry," the Falmouth governor said later in the meeting.

"It's a good day for Nantucketers. This certainly demonstrates that the board of governors listens," said Tim Soverino, chairman of the Nantucket selectmen.

The announcement about the change in direction on the service model came amid continued expressions about the need to find solutions to the growing tangle of long-range planning problems confronting the boat line.

"I think we still have the challenge - in my mind I still think there is a list of very critical issues, and I think we need to keep those issues on the radar screen," Mr. Tiberio said.

Only SSA board chairman and Vineyard governor J.B. Riggs Parker appeared to cling to a rigid position, reiterating the same warning speech he issued to the people of Nantucket on the night of their public hearing last month.

"It's important for everybody to understand that you can't have it both ways. Choices have consequences. Are you prepared to pay for the cost of continuing with the existing service?" Mr. Parker said.

But Mrs. Grossman told Mr. Parker that there is still no real basis for believing that the service model would save money on the Nantucket run.

"We don't have any information that really shows us [savings under the service model]," she said.

Aimed at developing a 10-year strategic plan for the boat line, the service model was unveiled four months ago.

The key concepts in the model included the futuristic high-speed ferry to Nantucket, the plan to shift freight traffic onto barges, and a plan to shift Vineyard-bound passenger traffic from Woods Hole to New Bedford.

If boat line managers now plan to abandon the high-speed ferry plan on the Nantucket run, Mrs. Grossman questioned the need to go forward with a two-day symposium on high-speed ferries next month.

But Mr. Tiberio, Mr. Parker and Mr. DeWitt all said the symposium will be a good forum for information.

"I think we should be as educated as we can be in terms of our options," Mr. DeWitt said.

Mrs. Grossman predicted that it will be more about hearing a sales pitch.

"These are all shipyards [that have been invited to the symposium]. They're salesmen," Mrs. Grossman said.

Mr. Tiberio said the symposium is tentatively planned for June 14 and 15. The place has not been decided yet.

In other business yesterday, boat line governors also approved a rare mid-season fare increase amid an increasingly dire financial report from boat line treasurer Wayne Lamson.

The fare increase was first proposed last month, as Mr. Lamson reported escalating costs from legal bills, rising debt and projected operating losses on the Schamonchi ferry run between New Bedford and the Vineyard this summer.

The fare increases will take effect June 1 and will include:

• A 50-cent increase in adult passenger fares.

• A $2 increase in auto excursion fares.

• A five per cent increase in freight rates for trucks over 20 feet in length.

• Extra barge unloading rates at the Nantucket terminal.

• An 18 per cent annual finance charge on unpaid bills over 30 days old.

Mr. Lamson said the fare increase is expected to net the boat line some $986,000 in additional revenues in the next four to five months, but he said it still may be necessary to dip into reserve funds for debt payments before the end of the year.

He projected that the boat line will end the year with an operating gain of about $2 million, but the treasurer warned that the numbers are uncertain, especially against a backdrop of lower-than-expected advance bookings for cars for the coming summer.

Also yesterday the SSA board approved a license request from the owners of Hy-Line Cruises to replace the high-speed passenger ferry Grey Lady II with a new and larger high-speed ferry.

Hy-Line owners want to build a new 300-passenger Grey Lady to replace the 149-passenger ferry that operates year-round between Hyannis and Nantucket.

The new ferry plan includes a plan to retire the Point Gammon, a conventional passenger ferry operated by the Hy-Line. Hy-Line owners want to operate the new Grey Lady at capacity for only two of the six daily trips, and they plan to carry only a maximum of 149 passengers on the rest of the trips.

The request was approved by the boat line board, but Mr. Tiberio said he has not yet developed a recommendation of what fee to charge the Hy-Line for the replacement Grey Lady operation.

Currently the Hy-Line pays the SSA 10 per cent of all fares collected for more than 40 passengers. Mr. Tiberio said management will return to the SSA board for approval of a new license fee within 30 to 90 days.

Murray Scudder, one member of the family that owns the Hy-Line, said yesterday that the decision about whether to replace the Grey Lady II will depend on the license fee.

Public discussion over the Hy-Line request quickly strayed into a broader discussion among Nantucket residents about the pros and cons of high-speed ferry service, especially the environmental impacts. On Wednesday the Nantucket selectmen voted to support the Hy-Line license request, but yesterday selectman Matt Fee told the board that the vote was 3-2, and he said there are some concerns.

"Sometimes we go full speed ahead on things without knowing what we are doing and why," he said.