Have been told that there are no MI's either for Margaret Madderall, James Maddrell buried 1806 Rushen or James Maddrell buried 1817 Rushen. Obtained this information through the look up exchange. The crew of the HMS Captain were discharged Aug. 1800 at Plymouth so maybe there is a ship's roster for that date., Google "Ships of the Old Navy" and scroll down to HMS Captain 74 (guns) for a full history of this ship.
Since this is the 200 hundredth anniversary of Horation Nelson's death, I might mention that the HMS Captain was Commodore Nelson's flag ship in 1796 and 1797. and the Battle of Cape St. Vincent occurred 14th Feb. 1797. After Nelson gave up command of this ship, the HMS Captain was involved in the blockade of Brest and 6 months in the Carribbean. James Maddrell was press-ganged the 7th Sept. 1798 off the coast of the Isle of Man. Assuming that he was quickly transferred from the press-gang ship, he would have been involved in those campaigns.

Hope you find out what happened to James Maddrell. It would make a good story for the journal.