{HEAD ~ The side edges} 2 slope inward from the top of {TAIL ~ the body board} T to the bottom surface B 
{ HEAD ~ The side edges } 2 slope inward from the top of { TAIL ~ the body board } T to the bottom surface B
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH