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