quarterdecker
/ˈkwɔːtəˌdɛkə/noun
A person or thing situated on or having a quarterdeck; specifically †(a) a gun situated on the quarterdeck (obsolete ); (b) an officer who serves on the quarterdeck; (c) a ship having a (specified type of) quarterdeck.
Origin
Mid 18th century. From quarterdeck + -er.