A downcomer for conveying wastewater from an upper level of a marine vessel to
a lower level of the marine vessel includes a pair of spaced apart mounting portions
and an elongate impact portion extending between the mounting portions. Each mounting
portion is adapted for attachment to the marine vessel, and the shape of the elongate
impact portion defines a concave space through which the wastewater is conveyed.
In one preferred embodiment, a synthetic elastomeric tube, hose, or liner is placed
within the concave space, and the wastewater is conveyed from the upper level of
the marine vessel to the waterline through the tube, hose, or liner. In another
preferred embodiment, the mounting portions and the elongate impact portion are
extruded to form a unitary structure including a lightweight, rust-resistant ultrahigh
molecular weight polyethylene.