Today, HULL SK 97, to be named PORTLAND SENTINEL Launching ceremony commenced at the auspicious time of 1058 hrs, with firing of crackers and bursting of fireworks. But it was not a launch in the usual sense. The vessel was slowing pulled aft by two winches on the launch barge, supported by a series of 12 hydraulic balloons. These balloons were also used to control the direction of the vessel’s movement from shipyard to barge.