U.S. Shuttle Tankers Blaze Trail
Overseas Cascade bow loading system and thruster
U.S. Flag Shuttle Tankers Blaze Trail
Two of OSG's newest U.S. Flag vessels will make history as the first shuttle tankers in the Gulf of Mexico. The Overseas Cascade and Overseas Chinook, on time charters to Petrobras America, will service the Petrobras-operated floating production storage and offloading facility (FPSO) at the Chinook and Cascade ultra-deepwater fields located 155 miles from Louisiana's coast.
Wanted: New Jones Act Shuttle Tankers
Because the FPSO is considered a U.S. port, its shuttle tankers must conform to Jones Act requirements. This means the tankers must be built in the United States, owned by a U.S. company and manned by U.S. citizens. OSG's newbuild Veteran Class tankers fit the bill, and the contract to enter this niche market was awarded in 2007.
Converting a product tanker to a shuttle tanker requires the installation of several primary pieces of equipment, including a controllable pitch propeller (CPP), a bow thruster and a bowloading system, as well as high-tech automation of these components.
The CPP system allows the propeller blades to rotate along its axis without changing the direction of the shaft rotation. The engine can remain running in one direction while propeller blades can be moved from neutral thrust to ahead or astern thrust. This enables a shuttle tanker approaching a floating offshore facility to make slow, subtle changes with no lag while waiting for the engine to start in different directions.
The shuttle tanker's bow-mounted loading platform allows for a transfer hose to be retrieved from the sea and connected to the cargo system. It permits an emergency disconnect or a completely dry disconnect. The hawser connection and cargo hose are controlled from the bridge via a comprehensive automation system. Through a closed-circuit video system, the mate on the bridge can control all aspects of cargo operations as well as station keeping of the vessel.
Project Management at Its Best
Successfully managing the first-ever U.S. flag shuttle tanker conversion tapped into the project management skills and talents of many shore and sea staff. The results speak for themselves. The Overseas Cascade delivered on time and is operating beautifully, and the same is expected of the Overseas Chinook.
Beginning in 2007, the initial planning phase for the project kicked off with U.S. Flag DPA John Doran leading a comprehensive risk assessment of shuttle tanker equipment and operations. The collective effort by OSG; Petrobras; BW Offshore, owner of the FPSO; and Edison Chouest, owner of the tug boat to be used during operations— resulted in the creation of a set of policies and procedures for vessel operation and field offloading. This information then fed into the technical design phase managed by Marine Engineer Jan Flores. From there, execution of the project was handed off to vessel operations, where Fleet Manager Greg Doyle and Technical Superintendent Dave Deltano took over. Dave, with the support of Naval Architect Kent Merrill managed the yard period.
"Although the Overseas Cascade presented engineering challenges, a great mix of teamwork and planning led to success with our first conversion and a set of important lessons learned that are now being applied to the Overseas Chinook," says Dave, who spent 101 days at the Detyens shipyard in Charleston, South Carolina for the first conversion and, as of the writing of this article, was back in Charleston. "The Detyens' team also deserves credit for providing solutions and support throughout the project."
High-Profile Test Run
The Overseas Cascade delivered ahead of the FPSO production schedule but was subchartered to the cleanup effort following the Deepwater Horizon oil spill, putting the crew and new equipment to the test under trying circumstances. Although the bow-loading system was not used, the taut hawser and dynamic positioning (DP) tug boat method of keeping the shuttle tanker on station was proven.
Greg says the number one concern during offloading is to not make contact with the FPSO vessel. "Both the FPSO and the shuttle tanker must be able to stay on station and 'weathervane' to adjust to changing currents while staying in position without anchoring," he explains. "This is accomplished by either using a shuttle tanker with built-in DP capabilities or with the taut hawser/DP tug method." Greg says that at the time of the Deepwater Horizon oil spill cleanup, a DP shuttle tanker was requested but none were immediately available.
"When a DP shuttle did arrive, it was unable to hold station on the drill ship, so the Overseas Cascade was brought back on the scene. It was a strong affirmation of our system and capabilities," he says.
Following its stellar performance during the oil spill cleanup, the Overseas Cascade headed south to Brazil to work while awaiting Gulf of Mexico production to begin.
A Well-Seasoned Crew
Given the harsh conditions of deepwater production, delicate maneuvers and advanced onboard technology, a highly experienced and well-trained crew is imperative to safe shuttle tanker operations. Nearly all senior officers for both the Overseas Cascade and Overseas Chinook are seasoned OSG employees. Prior to the vessels leaving the yard, both crews will have trained on board with equipment manufacturers, attended simulator training in the United States and observed onboard shuttle tanker operations in Brazil.
Captain Brett House spent three weeks in the shipyard, training and preparing the vessel prior to taking the Overseas Cascade down to Brazil for the first offloads from FPSOs.
"As the vessel operator, in the yard we review equipment and operations, discuss safety, and bring to Dave any concerns or needed changes," he says. "Most of us have been on ships for many years, so it's been great to see our collective experience come together to continually improve operations."
According to Greg, the key to the success of these vessels is the skill and dedication of the crew. "Captain House and Captain Roy Coleman (each 20-year OSG veterans), along with Chief Mate Jon Gagne, Bosun John Zepeda, Pumpman Wayne Roberson and Steward Donna Decesare, all made strong contributions on the Overseas Cascade," he says.
As U.S. citizens, the Overseas Cascade crew requires Brazilian work visas while the vessel is operating there. The process to obtain the visas can take up to 60 days, making crew change very difficult.
"These challenges have required the crew to be more flexible then typical coastwise crews," says Training Manager Mike Blunt, who took on the difficult task of obtaining the visas. "We continue to improve the process and greatly appreciate the sacrifices and inconveniences our crews have dealt with to ensure continued high-quality service to our customer."
New market entry, sophisticated new vessels, flawless project execution, a high profile test run—it's all adding up to a good news story for the U.S. Flag fleet in 2011.
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