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