From heavy-lift ship to deep-sea cable layer

Under the blue hull paint, the Russian characters of the original name remain as a faint memory. Just above them, the strong white lettering the current name stands out: Bold Endurance. Built for the Russian navy by Hollming Ltd. of Finland in 1978, the 458-foot ship began life as a heavy-lift vessel. Purchased by the Canadian-based Secunda Marine Services in the mid-1990s, the ship was taken to a Korean shipyard for an extensive structural refit. The ship then went to England for the installation of cable-laying equipment by charterer Global Marine Systems to make her the 8,300-dwt fiber-optic cable-lay vessel that it is today.

The master, Capt. Doug Corkum, from Nova Scotia and the descendant of a long line of Atlantic fishermen, has been with the ship since the handover from the Russians. At that time, the forward house design allowed for a 295-by-45-foot-long after hold with a watertight transom door. Secunda purchased two of the three ships built in the class. They were known as ro-flo ships for their ability to flood ballast tanks to submerge partially so that smaller submarines or other floating equipment could be loaded aboard without lifting.

Because the vessel was built as a heavy-lift ship, the whole engine room is under the floor of the cargo hold. The sidewalls, from the transom forward to the accommodation area, are double walled. The double sidewalls provide ballast, and the engine room below the cargo hold provides positive buoyancy while permitting a large hold open to the stern. This huge area was covered with seven hatch covers that could be lifted off with a mobile gantry crane to create a huge, open hold area.

The ro-flo design was perfect for conversion to a cable layer. The watertight stern door was welded shut, and a large generator room was fitted with one Cat 3512- and three Caterpillar 3516B-powered generators to provide 440-volt electrical services for the cable-laying equipment. Ship service at 380 volts is provided by three Wärtsilä-powered generators in the engine room. Forward of that are four huge, 43-foot-diameter by 20-foot-deep, round cable tanks. Except for a 10-foot-diameter central core, these tanks can be filled entirely with fiber-optic cable. The total amount and length of cable onboard will vary with the job to be done, but the tanks can hold up to 5,450 tons of cable. Depending on the diameter of the cable, this is enough to stretch hundreds of miles. If it is deep water and in less need of protection from trawl net doors or anchors, the little strands of fiber-optic cable will be protected by a neoprene armor to a thickness of about 1.5 inches. For shallower waters, the cable will be 3 to 4 inches thick. For a large job, the loading of cable can take several days. An additional smaller cable tank can be used as a spare.

More cable than any other

The actual cable work is done by Global Marine Systems crew. The aft deck, on top of the sealed former hatch covers, is crowded with their containerized special equipment rooms for splicing cable, controlling the plow and a number of other technical functions. Global Marine maintains that it has buried more submarine cable than any other company. It laid approximately one third of the 78,293 nm of subsea cable installed in 2001, of which more than 40 percent was plowed into the seabed. Some of that was laid by Bold Endurance. “We can spend up to two months at sea,” Corkum explained. “We carry more than enough fuel and can make 20 tons of water per day; it is only the food to feed the crew and cable-laying personnel that limits us.”

As with research ships, a cable-laying ship has two parallel crews. In this case, the ship’s crew — comprised of Canadian officers, Philippine seamen and Ukrainian engine-room crew — work for Canadian-based Secunda. The cable-lay crew, mostly English and Filipino, work for U.K.-based Global Marine. Total numbers vary depending on the type of contract, which ranges from remotely operated vehicle (ROV) inspection of older cables to the laying of new cable using a towed plow. The Barbadian-registered ship has accommodations for 60 people, and a typical ship’s crew is 23, leaving lots of room for cable crew.

A recent job for the ship was the inspection of cables off the California coast. In this operation, the ROV was guided along the existing cable to videotape it and inspect for damage. If damage was found, a simple grapple was dragged across the seabed to pick up the cable, which was brought aboard and fed into a splicing room on deck where a new section of the appropriate size was spliced in place before the cable was returned to the seabed.

On the job between Manila and Singapore, Bold Endurance crew laid cable out into the South China Sea from Manila, then on reaching the halfway point, they marked the location and dropped the cable end to the ocean floor. The ship then went to Singapore and laid cable out from that end. When they arrived at the halfway point, they recovered the other end of the cable from the ocean floor and spliced the two together to complete the job.

Burying the cable

Depending on the composition of the seabed and the potential danger from natural or manmade damage to the cable, they bury the cable or leave it exposed on the ocean floor. On the main deck at the stern, a massive 35-ton gantry can be swung aft, taking with it a huge seabed plow. The leading edge of which is like a farmer’s plow, but on the trailing edge there is a slot into which the cable feeds and is laid in the bottom of the furrow. Depending on conditions, the ship can tow the plow to lay and bury cable at depths to 5 feet beneath the ocean floor and at water depths up to 4,900 feet. With the plow, speeds of about 2,600 feet per hour are common, although it can be worked at speeds of more than 1.6 nm per hour in ideal conditions. Working in deeper water — Corkum reported laying cable in depths to 24,000 feet — they simply lay the cable on the ocean floor at speeds up to 5.3 nm per hour. A complex system of rubber-tired wheels holds the cable back as it is being paid out, so as to maintain an appropriate tension without breaking the delicate line.

Weather can be a limiting factor in cable-laying operations, “We have worked in 40- to 50-knot winds, but if it is on the beam, it can cause wear on the cable casing, so we have to stop,” Corkum said. “If it looks like it will get really bad, then we cut the cable and do a controlled drop with set ground tackle that can be retrieved later. If it is less severe, we will jog into the wind until it goes down and then start laying again.”

This sort of dynamic-positioning (DP) work requires navigation skills and a full slate of position-holding aids. When the ship was converted, a skeg was added at the stern to provide space for two 1,500-hp stern thrusters to match the two 1,500-hp bow thrusters. The main engines are a pair of 3,000-hp Pielstick medium-speed (490-rpm) diesels turning controllable-pitch propellers. The ship has roughly the same power for transverse movement as fore and aft. Equipped with a Kongsberg-Simrad SDP 11 single-station DP-1 system, it can track to the precise waypoints that the cable layers require, or hold position while the ROV is inspecting a specific section of cable.

Propellers work hard

Given the complexities of the electronics onboard, Bold Endurance carries electrical technical officer Michael Fearn, who got his sea legs on British Columbia fishing boats and his computer fingers creating video games with the neighbors in a small coastal fishing community. On the bridge, Fearn explains that the DP system approximates the reliability of DP-2 with a redundant operations computer. The DP system is linked to all six of the ship’s propellers. As satellites pass over and seas buffet the vessel, the six propellers can end up working quite hard to hold the vessel in position.

When water depths permit and the ship has to hold a stable position for chores, such as tending the ROV, an alternative position reference is available. From a small crane mounted on the port side about midship, a taut wire with a weight affixed is lowered to the ocean floor by a constant-tension winch. At the end of the crane, boom sensors detect the angle of the wire. The winch maintains a constant tension on the wire, and the sensors note any changes in the angle of the wire. This data is fed to the ship’s DP system, which then activates the propellers to restore the angle to its original position, thus keeping the ship stationary in relation to the weight on the ocean floor. This system is typically used in depths of less than 656 feet but can, in calm waters, work to depths of 1,300 feet. It requires much less action by the propellers to hold position.

When not at sea, Bold Endurance is currently stationed at the cruise-ship dock in the very attractive harbor at Victoria, B.C. The ship attracts a steady crew, who tend to return for repeated voyages over the years. The multinational make-up of the crew is recognized in the mess area, where marine charts of the Black Sea, the Philippines and the United Kingdom share space with Canadian east-coast and west-coast charts. In this fashion, while the ship is contributing to modern global communications, the crew ease that age-old mariner’s longing for home waters.

Alan Haig-Brown is a freelance writer based in British Columbia.

By Ocean Navigator