at least two housings coupled to {HEAD ~ the hull} by {TAIL ~ beams} forming a hydrofoil 
at least two housings coupled to { HEAD ~ the hull } by { TAIL ~ beams } forming a hydrofoil
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH