Tide and Current

Double Hulls: Keeping the Oil Off the Beach

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One of the hand-holds on the main computer and navigation console on the bridge of the new double-hulled tanker Polar Endeavour has been given a traditional twine lashing like that which sailors traditionally put on the mid-ship spoke of a wooden ship’s wheel. It is a fitting testament to the maritime history that has led to this modern expression of technology, as it is at the same time a reminder that it is seamen who will take her safely over the seas The lashing is also a testament to time spent by an anonymous sailor on watches bringing the ship around the Horn from Atlantic to Pacific waters. As such it honours the early navigator Captain Cook who made the same voyage on his ship, the namesake for the modern vessel — Endeavour.

In the 18th century the original Endeavour took the route south around Cape Horn as that was the only navigable route from Atlantic to Pacific, while the Polar Endeavour took that route after delivery from her makers at Litton Avondale in New Orleans due to her beam. The canal could have accommodated her 895-foot length, but her 152-beam beam is nearly 50 percent wider than her namesake is long or than the 106-foot Panama Canal width limit.

This is a big ship. In a large part she can be considered a ship within a ship. When the Exxon Valdes ran aground on an Alaskan reef, her single skinned hull was easily opened and the thick gooey black crude oil instantly poured out in the cold clear waters of Prince William Sound. Had the Exxon Vales been built with a double hull it is probable that there would not have been a spill and the oil companies would have saved billions of dollars in clean-up cost and payments to fishermen. Even with the additional costs of a double hull, redundancy in systems and advanced navigation, the Polar Endevour and other ships like her that are being built in shipyards around the world are cheap at the price and required by law in US waters. Of course they also protect the environment, but looking at the lethargic attitude of major global oil companies in apply this technology where it is not required tells that it is law that they understand. Canadian shipyards can only look longingly at vessels like the Polar Endevour and any other working boat in the US as the law in that country requires that vesssels trading between US ports must be built in the country. Canada has been remarkable and tragically negligent of similar protection for its own shipyards.

Visually the most striking feature of the ship is the fully enclosed bridge and bridge wings. On entering the bridge, one gets an overwhelming sense of space stretching to port and starboard, then the eyes are drawn to the Raytheon integrated navigation console. Similar to that seen on fast catamaran ferries, its T-shape carries a total of seven screens in the console, two for radar can display either 10-cm and 3-cm radars, one NautoConning, one ABB (machinery and cargo control system) and one MCA hull monitoring system. The NautoConning monitor on the centre line can be cycled through six different modes to show every aspect of the ship’s complex array of systems. These include navigation, docking, piloting, sensor, bell book and Alarm. Each of which were defined by the captains and customized by Raytheon. On the “navigation” mode the usual GPS, water and bottom speeds, time and heading information is provided as well as wind speed and direction with drift and set of the vessel. Central on this display are digital metres showing the pitch of the 3000 HP bow thruster, and each of the ordered and actual pitch of the ship’s two controllable pitch propellers along with the shaft RPM and rudder angles. Turn rates, headings and waypoints information are among other data on that screen. In spite of the large amount of data, the large screen format can be read at a glance. Other screens in the system are equally easy to read with Sensor giving data from three GPS and two Gyros, Bell Book giving engine information while Alarm provides instant alarm recognition, depth and radar alarm management. The MCA monitor displays accelerations, pitch, roll and bow emergence. More than available data, this bridge console is noteworthy for the careful planning that results in data being made available in a visual fashion that makes it immediately usable by the bridge team.

In a walk through of the operational modes of the bridge when I spent some time onboard in early August of 2001, Capt. Ken Zeghibe, who had just delivered the ship’s first cargo of Alaskan North Slope crude to Puget Sound, explained the origin and functions of the system. Along with Captain Dindio, who took the ship out of the shipyard and delivered it around Cape Horn to Alaska, Zeghibe rode a high-speed ferry between Sweden and Denmark and recommended this system for the bridge of the new tanker. It has several progressively more automated levels of operation for steering and throttle.

Over all of this a Sea Auto Mode allows for auto pilot headings to be dialed in. While a Harbor Mode in level one allows the joystick to be tilted to starboard and the ship will literally move sideways to a dock. In the simulator on which captains, mates and pilots have trained an exercise has the operator take the ship up to the turning basin in Miami Harbor and with the ship on “Stop” a 180 degree course change is entered in the auto pilot in 30 degree units with the pivot point set amid ships. The ship turns herself on her own length. Explaining the approach to the dock at the TOSCO refinery in Ferndale Washington that he and the pilot worked out the night before Zeghibe explained, “Last night the flood was still running and so was taking us into the dock. We took it off Harbor Auto and let the bow fall into the pier. We put it on Harbour Manual and changed the rotation point from midship to bow. This pinned the bow and we simply rotated the aft end into the pier.”

While there were tugs made up fore and aft, as required by regulation, this docking was carried out without any assistance from them. When docking the captain and pilot move out to one of the bridge wings where all of the essential controls are replicated in secondary consoles. The extended wing gives a clear view to the pilot down the line between the ship and the dock face as well as of the deck, some 62 feet below.

For the deck crew, docking is made easier by the installation of winch controls along both the starboard and port shear. An operator standing at the control has a clear view of the dock and of the line winch. These winches feature large split drums, like those on the bow winch of a docking tug, to allow for line storage on one side of the drum and the working length only of line on the other. The ship has a full one metre raise on the centre line to provide adequate camber to clear the decks of water.

Pumping operations are overseen from the cargo control room on the “A” deck level where an ABB Machinery/Cargo Control System two screen console has access to all the functions necessary for controlling the main engines and hence the speed of the pumps as well as screens allowing the opening and closing of all valves.

On the same deck level, the ship’s single mess is a planned contribution to the team approach to vessel operations that has been encouraged from design to construction and now operation. With all 20 crew eating together, rather than separated into officer and crew mess, it is expected that there will be a better flow of information and heightened safety of operation. A mess crew of three, steward, cook-baker and one mess person prepares meals. The galley is huge, even by the standards of the crew coming off other tankers in the Polar fleet. Large walk in freezers and coolers stock enough stores for even the longest voyages. In addition to the three galley crew, the ship’s complement includes Captain, three mates, three watch standing ARPA-certified A/Bs, a Chief Engineer, three assistants, and six maintenance persons. Crew responsibilities are flexible and shift according to port or sea time and work demands on the ship. Provision is made for up to four hours of overtime work apart from the standard eight hours of watches.

Like the bridge and cargo control rooms, the engine room is a marvel of technology and redundancy all designed to keep the ship off the rocks and the engine room dry. The same ABB Machinery/Cargo Control System consoles with access to the same data as in the cargo room and on the bridge are located one in the starboard machinery control room and the other directly opposite, through a watertight door, in the machinery control room. The port machinery control room is set up to operate the port engine room, whereas the starboard machinery control room is set up to control both the port and starboard engine rooms. Each engine room in itself has all the redundancies found in the engine room of any single screw vessel. For the first 3000 hours of service the engine room would be operated as fully manned. After that it was be eligible for certification as an unmanned engine room.

Apart from the minor differences in the control rooms and a machine shop located on one side, the two engine rooms are identical and can be isolated from each other on all deck levels by a centre line fireproof watertight bulkhead. Each engine is served by an independent fuel system. The Porsgrunn rotary vane steering gear features four compartments in a circular void around the top of the rudder stock. Hydraulic oil is pumped into two of the compartments and out of the two adjacent compartments to turn the rudder. This assures redundancy on each rudder should one of the oil compartments fail. In addition, even working with a single rudder, the ship still surpasses International Maritime Organization maneuvering standards.

The complexities of the systems on any large ship are difficult to reduce to a simple word picture, but those of this ship are comparable to the most sophisticated military vessel in their diversity. Designated the Millennium Class tankers, even their design process was long and complex. Based on proven technology, it was developed in partnership with leading naval architecture and marine engineering firms. As did the captains, Chief Engineers Steve Jellerson and Tom Cromwell traveled to Norway early in the process where they spend 18 days on board the North Sea tanker Elizabeth Knutsen. “We were not at all prepared for the advanced technology that we saw there,” recalls Jellerson, “When ARCO sat down to design these ships, they asked two questions, ‘What have we learned from 25 years in the Gulf of Alaska and who else in the world is doing what we do and what can we learn from them?”

Sounds rather like the questions that Capt. Cook might have been asking himself as he set out on his voyage that would change our understanding of the world. This new ship, along sister ships and similar vessels already delivered or on order, are certainly changing the standards and understandings around the transport of crude oil in ships and keeping it off the Pacific Coasts of North America.