HMS Mastiff was a British 12 gun brig . The ship was converted into a 6-gun brig between 1820 and 1825 and then served as a research ship . From 1825 to 1836 the ship was used to explore the Mediterranean , from 1836 it explored the waters around the Orkney Islands . From 1842 the Woodlark served as a tender for the HMS Mastiff.