{HEAD ~ The concavity} has {TAIL ~ a longitudinal axis} of symmetry coincident with a longitudinal axis of symmetry of the watercraft 
has
{ HEAD ~ The concavity } has { TAIL ~ a longitudinal axis } of symmetry coincident with a longitudinal axis of symmetry of the watercraft
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH