Powerful escort tugs reduce coastal oil tanker risks
Powerful escort tugs reduce coastal oil tanker risks
Written by: Robert G. Allan for The Prince George Citizen, February 1, 2014
As a frequent kayaker in the beautiful midcoast of B.C. I am well aware of what is at risk from a polluting incident. However too much discussion to date has been centred on oil-spill recovery capabilities, and very little on the far more critical spill prevention measures necessary to protect this sacred coastline.
It is critically important to understand the proven maritime technologies available today to safeguard our coast.
The spectre of another Exxon Valdez tragedy is often cited as a likely outcome of increased tanker traffic on the B.C. coast. However, that incident sparked dramatic changes in the maritime world with the promulgation of various international laws and the US Oil Pollution Act of 1990. To ensure that such an incident could not be repeated, all single-hulled tankers (such as Exxon Valdez) have been mandated out of service since 2010, by the enactment of the International Maritime Organization Marine Pollution Act (MARPOL) Annex 1, and as affirmed by Canada under the Canada Shipping Act; Vessel Pollution and Dangerous Chemicals Regulations.
The exclusive use of doublehulled tankers means that in the unlikely event of a grounding, a great deal more energy must be expended to breach an inner cargo tank to cause a spill than was previously the case.
A tanker is a machine which can occasionally have mechanical problems with its propulsion or steering systems. If problems occur well out to sea there is almost no risk; the crew should be able to fix the problem in short order.
If however that failure occurs in a near-coastal environment, there must be systems in place to ensure that the tanker does not go aground. Enter the high-performance escort tug.
Since 1990 extensive research and development has led to the design of large and very powerful tugs which act as an emergency steering device in event of a tanker rudder failure, or as a very powerful hand brake in case of a propulsion failure.
A significant majority of these escort tugs worldwide have actually been designed in Vancouver by Robert Allan Ltd., and operate at major oil and gas terminals throughout Europe, U.S.A., South America, the Middle East, Africa and Asia.
The capabilities of these tugs have been verified by extensive scale model-testing and research, and by full-scale trials. Featuring unique hull forms which can generate very high hydrodynamic forces, and with powerful 360 degree steerable thrusters, these escort tugs bear little resemblance to the small log or barge towing tugs with which British Columbians are familiar.
Designed to provide forces equivalent to or higher than the tanker’s own steering and braking capabilities at high operating speeds, an escort tug operates tethered to the tanker and is immediately available to exert very high steering or braking forces as required.
Based on our extensive experience designing the world’s most capable high-performance escort tugs, we have recommended to the Northern Gateway Pipeline project the largest and most capable tugs of this class operating anywhere in the world.
At 50 metres long, with more than 10,000 horsepower, they can generate up to 200 tonnes of corrective steering or braking forces, stopping a tanker within 300 metres of sideways transfer.
These will dwarf any existing tugs on the B.C. coast.
They are designed to provide the necessary tanker escort capability and also to perform rescue towing should a non-escorted tanker be disabled anywhere within the 200 mile limit of Canadian waters off the B.C. coast.
Two of these monster tugs will escort every laden tanker outbound from Kitimat, with one freerunning tug checking the route ahead of the ship and one tug tethered astern. Inbound, empty tankers will have one free-running escort, aft of the vessel.
In addition to the huge safety margin provided by using escort tugs, no less important is the extra number of trained eyes and ears available within the escort system to detect a potential incident.
The lead tugs will identify any potential marine hazards, suggesting course or speed corrections as necessary.
The master of the stern escort tug is uniquely positioned to detect any potential off-course error of the tanker, where he can exert corrective action within seconds.
In addition, the presence of two B.C. coast pilots aboard the tanker itself, plus the ship’s captain, means no less than five professional mariners are paying attention to the tanker course at all times.
The use of such extensive tanker escort tug systems will provide as close to a zero risk operation as is possible.
Robert G. Allan is executive chairman of Robert Allan Ltd., a leading naval architecture and marine engineering firm in the field of high-performance commercial ship design, based in Vancouver since 1930. He has been internationally recognized for his developmental work in the field of escort tug designs.
