The inventive structure includes a tunnel that defines a concavity formed in {HEAD ~ a hull} of {TAIL ~ the watercraft} 
of
The inventive structure includes a tunnel that defines a concavity formed in { HEAD ~ a hull } of { TAIL ~ the watercraft }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL