{HEAD ~ A related object} of the invention is to have {TAIL ~ the last step} in the series have a simple recess aft of it to thereby minimize wetted area resistance 
is to have
{ HEAD ~ A related object } of the invention is to have { TAIL ~ the last step } in the series have a simple recess aft of it to thereby minimize wetted area resistance
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH