HYANNIS - In the latest skirmish in the continuing battle between the Tisbury board of selectmen and the Steamship Authority, the port council yesterday backed a boat line plan to shift three summer trips from Vineyard Haven to Oak Bluffs.

The decision by the council, which advises the SSA board of governors, came over the bitter protests of council member and Tisbury selectman Thomas W. Pachico and fellow selectman Tristan Israel. The council voted 5-1, with Mr. Pachico dissenting and Nantucket member Nathaniel Lowell absent, to back the SSA plan.