The concavity has {HEAD ~ a trailing end} coincident with the transom or {TAIL ~ trailing edge} of the watercraft and has a leading end disposed forwardly of the transom 
coincident with
The concavity has { HEAD ~ a trailing end } coincident with the transom or { TAIL ~ trailing edge } of the watercraft and has a leading end disposed forwardly of the transom
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH