ringsail
Webster's Dictionary (GCIDE)
Ringtail \Ring"tail`\, n.
1.(Zool.) A bird having a distinct band of color across the tail, as the hen harrier. [1913 Webster]
2.(Naut.) A light sail set abaft and beyong the leech of a boom-and-gaff sail; -- called also ringsail. [1913 Webster]
Ringtail boom (Naut.), a spar which is rigged on a boom for setting a ringtail. [1913 Webster]