Thomas is elusive, he is probably different from Thomas6(Ezekiel5), the latter is buried in the Ezekiel Brownell cemetery at Brownell's Corner in Westport. He died 11/20/1876 and married 1) Nancy Chase and 2) Abby Petty.
The New Bedford Public Library site has an entry for a Thomas Brownell, age 18, oarsman, 5'7", light skin, aboard the brig "Sally" out of Westport (a tiny port, compared to NB or Nantucket) in 1812. Thomas6 would have been 14 at the time, so this could be a different one. In the 1840s a Thomas M. Brownell, oarsman, makes two voyages on the bark "Barclay," and in 1851 is a boatsteerer aboard the "Solon," all sailing from Westport.
Lucy (Sherman) Brownell was the daughter of Charles5(Jonathan4, Joshua3, John2, Philip1) Sherman (1769-1807) and Lois Taber, the latter a descendant of the Mayflower passengers Francis Cooke, John Cooke and Richard Warren.
Sources: Roy V. Sherman, "Sherman Genealogy" CS 71 .S552 (1968); Ralph V. Wood, "Francis Cooke of the Mayflower Through Five Generations" p. 389.