At the Gannon and Benjamin Marine Railway in Vineyard Haven, shipwrights have stepped back in regional maritime history. They are building a new 28-foot 19th-century whaleboat. The boat is one of nine being built across the country for the last remaining whale ship, the Charles W. Morgan, now undergoing restoration at Mystic Seaport. The work began a month ago. Nat Benjamin, the owner of Gannon and Benjamin boatyard, calls it a great honor to be a participant. The Charles W.