When the chamber is filled with sufficient air, {HEAD ~ the rearward section} becomes buoyant and pivots to {TAIL ~ its floating position} 
pivots to
When the chamber is filled with sufficient air , { HEAD ~ the rearward section } becomes buoyant and pivots to { TAIL ~ its floating position }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL