Cascade General Attracting Larger Vessels

By Derek Deere, Managing Editor of DryDock

This operator of the Portland Shipyard in Oregon has of late been improving its ability to compete in the international market by offering fast turn-around times that they stick to. Competitive pricing, plus a speedy job has meant that bulk carriers and containerships loading on the US west coast are increasingly favouring the yard.

Extending the approach pioneered by the Voyage & Small Vessel Repair Division to a service for the large international fleet, Cascade has implemented a reorganisation of labour and management practices at Portland, all aimed at treating the owners and vessels well during their stay.

With voyage repair stations located in Astoria, Oregon, at the mouth of the Columbia river and at Port Angeles, Washington, gateway to Puget Sound and Vancouver, Cascade is available to something like 10 000 international ships that visit the Pacific Northwest each year.

Rudder installed afloat

When the rudder of the four year old, 74 500 dwt Capitano Giovanni broke in mid-Pacific en route from Australia to Alabama, the Italian owner Deiulemar Line Took up a repair contract with Cascade while the ship was under tow. On her arrival in mid-September Cascade had already fabricated a new rudder using original design drawings and after consultations with Fincantieri the original builder.

The 225 m long ship arrived dockside at Cascade still with her 55 000 t of coke on board and at a draught of 11 m she could not be drydocked. However, after consultation with the owners and the Italian classification society RINA it was agreed to trim the ship by 2.5 m down by the bow in order to raise the stern.

A 6 m by 4 m cofferdam was flooded and floated under the broken rudder, about two thirds of which was missing. Working 2 m below water level the crew removed the stub of the rudder and removed it. The 12 m rudder shaft and steering gear, weighing 55 t, was removed and suspended above the dock for a laser alignment test. The shaft was found to be undamaged. The replacement rudder casting was flown in from Italy and machined on site to tolerance, with a tapered bore. The casting was aligned and then welded to the new rudder in a 200ºC environment using the Cooper Heat Method. As the old rudder had fractured across the rudder nut aperture, Cascade engineer's specified that a 125 mm deep intercostal flange be added to the framing above and below the opening.

To provide future monitoring for unusual vibration patterns - which was under suspicion for fatiguing of the old rudder - Cascade General Technical Director Paul Smith and Angels Balzano, on-site Technical Advisor/Port Engineer for Deiulemar contracted with testing specialists MEI-Charlton of Portland, Oregon to supply remote monitors to be attached to the inner side of the rudder's 28 mm plating, the leads from which were collected into a single wire emerging from the top of the rudder. An inspector from RINA approved all work before the rudder interior was coated and sealed.

After pressure and magnetic testing of all welds on the new rudder, two small cofferdams were attached to either side of it; enclosing port and starboard rudder-nut access apertures respectively. The rudder was then transported to the berth alongside the ship for final fitting of the rudder stock. With the vessel still trimmed down alongside, the new rudder was partially flooded, lowered under the ship's stern and carefully drifted into place using air falls. The stock casting was aligned with the lower shaft bearing in the ship's bottom and the tackles made fast.

The rudder rigged in place under the ship at Cascade, with a cofferdam enclosing the rudder nut access aperture

With the ship still down by the bow, the rudder shaft assembly had to be lowered back into place at an off-vertical angle, after which the rudder-nut was tightened hydraulically. Special attention was given to the welded plate sealing the rudder-nut aperture: It was tested ultrasonically to ensure 100% integrity.

The electronic lead from the newly added vibration sensors was fully connected to an onboard computer via a new sea chest aft of the rudder shaft. The data collected from this monitoring system is transmitted digitally to MEI-Charlton periodically and examined for any destructive vibration patterns that could affect any of the nine ships in this class.

Other work

Vessels handled recently include the 224 m long tanker Land Angel of Hong Kong that was drydocked for rudder repairs and new pintle pins with work subsequently extended to include propeller repair, shaft seal replacement and new piping.

The self-discharging bulk carrier Christoffer Oldendorff of 227 m length drydocked in late October for blasting and coating plus shaft inspection work. Work included hull repairs, propeller and bow thruster overhaul deck items and engine maintenance. Late, in December, a hydraulic levelling cylinder broke down while the ship was in San Francisco and Egon Oldendorff used Cascade's Voyage & Small Vessel Repair Division to lift the cylinder off the ship in San Francisco, repair it and reinstall it in Virginia.

The 110 m long pipe layer CSO Constructor experienced bow thruster problems and after off-loading the pipes she was carrying she was lifted onto drydock No.3 where work included also overhaul of sea valves, anchor windlass, crane repair, deck gear and piping replacement. The vessels Hai Kang, a Chinese 224 m BC had afloat repairs done on a forepeak bottom hull fracture using a vacuum box technique pioneered by Cascade General. Another BC, the 181 m Liberian Packing was drydocked, blasted and coated.

Related articles

Cascade General
Reinvents Itself