{TAIL ~ said concavity} at said trailing end of said concavity having {HEAD ~ a depth} sufficient to accommodate said impeller such that a central hub of said impeller is positioned at an elevation substantially equal to an elevation of said output shaft of said engine 
{ TAIL ~ said concavity } at said trailing end of said concavity having { HEAD ~ a depth } sufficient to accommodate said impeller such that a central hub of said impeller is positioned at an elevation substantially equal to an elevation of said output shaft of said engine
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH