A Corps of Engineers report says it would be economically feasible to deepen Boston harbor's shipping channels.

The Corps' New England Division said it would cost $22.7 million to deepen the main ship channel as well as channels in the Mystic River and Chelsea Creek from 35 to 40 feet. Some 35 percent would be paid locally, if the proposal goes through.Petroleum and scrap metal terminals would be the main beneficiaries of such a project, said Mark Habel, the Corps' project engineer.

We think it's a good project. The economics are there, he said.

Most ships other than tankers do not have draft problems when they call at Boston. The deepening project would not be necessary to handle the giant Econships acquired last month by Sea-Land Service Inc.

The vessels, renamed the Atlantic-class ships, are capable of carrying 4,400 20-foot container units or their equivalent, but the ships will be limited to 3,400 TEUs when they re-enter service in early spring. As a result, there will be no problem for them coming into Boston harbor, officials said.

Under the proposal, the Mystic River-Chelsea Creek confluence and a maneuvering area outside the South Boston Reserve Channel would also be dredged to 40 feet.

The Massachusetts Port Authority, which the Corps said has indicated its willingness to sponsor the project, is supportive in principle, a Massport spokeswoman said. We are not bound by any funding mechanism, she added.

Larger tankers, drawing up to 40 feet, would cut costs for petroleum terminals. Some tank farm operators now must bear costs of lightering before tankers currently calling can enter the 36-foot deep Chelsea Creek, home to most of Boston's oil tank farms.

Officials at both Northeast Petroleum Corp. and Revere Terminal Co., the latter a subsidiary of Global Oil, said they favor a 40-foot channel. Their most pressing problem is a bridge over the creek.

William Mitchell, a Boston harbor pilot, said Boston Inner Harbor has a peculiar channel system dating to World War II, when heavily laden outbound convoys set the pattern for a dredging plan. The 600-foot-wide outbound channel is about 40 feet deep, with some shoaling, while the inbound lane of the same width is only 35 feet, also with shoaling.

Mr. Habel agreed that the channel depths are somewhat unique, but that analysis of current and projected shipping needs indicate the current channel layout is sufficient.