Deck Cargo Barge on Delivery Voyage to Canada
Photo: Robert Allan Ltd.
Image: Robert Allan Ltd.
A 16,000 DWT deck cargo barge, Seaspan 252, was handed over to its owner, Seaspan Marine, in August, 2015.
The barge, 114 meters long by 27.5 meters wide with a depth of 8.4 meters and classed ABS +A1 Barge, was designed by Robert Allan Ltd. of Vancouver, B.C. and constructed by Seabridge Marine Contractors Ltd. at Jiangsu Yanzijiang Shipbuilding Co. Ltd. in China.
Launched on July 31, the barge is now being towed by Seabridge Marine’s tug Pacific Hickory to British Columbia and is due to arrive in late September. It will be put into service hauling limerock from Texada Island to Portland, Oregon.
The barge has a flush deck and raised forecastle. The hull form includes a semi-spoon, seagoing bow, round bilges and a stern rake with sidewall skegs. A three-meter-high steel cargo box surrounds the main deck. The limerock is loaded by a shore-mounted conveyor system. Unloading is accomplished by two large front end loaders which operate on top of the cargo load, feeding a hopper located amidships that in turn feeds a short shuttle conveyor to shore. The conveyor system as well as the deck machinery consisting of an anchor windlass, bridle winch and two mooring capstans, are powered by a 72-kilowatt John Deere EPA Tier III generator installed in a machinery space at the bow.
Primarily intended for towing on a hawser, the barge is fitted with twin skegs aft for directional stability. As this type of skeg can represent 25-30 percent of the total resistance of the barge Computational Fluid Dynamics (CFD) analysis was used by Robert Allan Ltd, to optimize the skegs and reduce their resistance as much as possible, while still maintain the necessary towed directional stability. All of this process is much faster and more cost-effective than traditional model testing, especially the directional stability analysis which is very difficult to do accurately in a small or medium-size laboratory tank, the designer said.
The Seaspan 252 is the latest addition to a fleet of specialized coastal cargo barges designed by Robert Allan Ltd over the past decades, but one of the first locally to embody the results of such an extensive CFD analysis.
