Pontoon PB Towed. A tug pulls the first pontoon out of the graving dock. There is about 4-10 feet of clearance on either side of the pontoon as it is floated out of the graving dock. December 6, 2006.Pontoon PA Towed. Tug pulls the second pontoon out of the graving dock as two tugs at bottom prepare to tow the third pontoon. December 6, 2006.Pontoon Q Towed. A tug pulls the third pontoon from this first construction cycle from the graving dock. All three pontoons were moored at temporary facilities in Blair Waterway until being towed to Seattle. December 6, 2006.Float-out Complete. Water leaves the graving dock after the pontoons were all floated out. After environmental inspections, the graving dock gate will be moved back into place, and the water pumped out of the graving dock to prepare for the second cycle of pontoon construction. December 6, 2006.<< Pontoon Float-outs Photos