Abstract: A drainage system for draining water from a top surface of a tarpaulin to prevent accumulation of water thereon, having a drain fitting including a top plate having a central aperture extending therethrough and a rigid tube integrally formed about the central aperture and extending downwardly therefrom. An open bottom end of the tube has a cutting edge formed thereabout terminating at a sharpened distal point structured and configured for puncturing and passage through the tarpaulin. A bottom keeper plate and locking element are removably fitted about the rigid tube being removably positionable into engagement with a lower surface of the tarpaulin in clamping relation to the top plate on the top surface of the tarpaulin so as to maintain the drain fitting in fixed attachment thereto. A flexible conduit is removably connected at one end to the open end of the rigid tube with an opposite end positioned in a drain hole or bilge of the boat so that water will drain thereto from the top surface of the tarpaulin.