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Saturday, October 1, 2016

Canada: Halifax Shipyard On Hand To Replace Lost Rudder

February 10, 2004

In November 2003 the Gorthon Lines AB vessel Margit Gorthon lost her rudder in the St. Lawrence River. The RoRo vessel features starboard side ramps and measures 463.9 x 73.1 ft. (141.4 x 22.3 m) and is 14,240 dwt. Halifax Shipyard visited the vessel and found that not only the rudder was gone, but the 343 mm rudder stock broken in three pieces and the steering gear flat bottom shell ripped and twisted. One of the pieces of the rudder stock was embedded in the rotary vane steering gear. All CP propeller blades were damaged beyond repair and had to be replaced. After some number crunching and discussions, Gorthon Lines AB decided to have its incapacitated vessel towed to Halifax Shipyard for repair in late November 2003. The vessel was docked in Halifax Shipyard's in their graving dock that is 567.6 x 77.1 ft. (173 x 23.5 m) with an 26.2 ft. (8 m) draft over the keel blocks.

The work scope included removal of the steering gear, its seat and the damaged deck and shell plates, remove the remainder of the rudder stock and access other peripheral damage, including the propeller blades. A new rudder had to be built; the rudder stock was a forging and difficult to create was dispatched from the Owner with the new propeller blades. The shell requires renewing as well as the aft peak tank top and a new seat manufactured and machined for the steering gear. As well as this a great deal of machining was required on the new rudder and the bottom and top pintles on the remaining stern frame as well as the new steering gear seat. Material was found for the heavy rudder top and bottom plates but stainless steel liners for the pintles could not be obtained in a timely fashion and as a result of this solid stainless steel rounds were used and drilled out internally to manufacture the needed liners.

The steering gear had to be removed in order to inspect and extract the remaining rudder stock. The stock was stuck fast and had to be drilled out before its removal.

The steering gear was then overhauled and renewed and replacement parts fitted as required.

The rudder itself was fabricated, fitted and welded in 12 days and then sent to the machine shop for milling, drilling and fitting of the mechanical aligned surfaces interfaces. The new rudder stock was machines and fitted to the rudder in the shop.

The Installation

The steering gear new seat was scribed to the deck plates and aligned horizontally before careful sequence welding to prevent distortion. The liners top and bottom were fitted to the stern frame, the rudder stock fitted and then the rudder and hardened down on the palm bolts. The hot work being complete the area was coated, cured and the vessel left on the December 22.



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