This allows a gas pressurizing blower to either maintain cushion gas pressure for {HEAD ~ minimum draft} or evacuate {TAIL ~ the gas cushion} from minimum above water profile 
This allows a gas pressurizing blower to either maintain cushion gas pressure for { HEAD ~ minimum draft } or evacuate { TAIL ~ the gas cushion } from minimum above water profile
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH