slip queen
n.— «At the same time, state officials are about to launch an educational outreach program aimed at marine boat owners. Nonnative tunicates sometimes attach themselves to hulls. Particularly vulnerable are so-called “slip queens,” or recreational vessels that rarely leave their moorage.» —“Sea squirts invade Puget Sound” by Susan Gordon in Dockton, Washington Seattle Post-Intelligencer (Washington) Mar. 24, 2008. (source: Double-Tongued Dictionary)