August 4, 2004
Classic Canadian tug repowered
"It is exciting to see our vessels coming and going through the harbor, I particularly enjoy that fact that we appear to be one of the busiest, and best looking fleets on the water," says Captain Bob Shields, president of Island Tug and Barge Ltd, looking out his Vancouver, B.C., office window.
Shields has built a reputation in the British Columbia towbat industry as an innovator.
Last year, Shields and his partner, Captain Jack Davies, retrofitted an Intercon connector to their 41.5 m by 9.75 m, 3,000 hp twin-screw tug Island Monarch.
Now, a year later, the is company repowering the classic raised-forecastle style 23.7 m x 7.32 m Island Crown with a pair of Cummins KTA38 engines.
The distinctively Canadian raised forecastle design resulted from a requirement that all crews' quarters must be above the waterline.
Built in 1974 to a Robert Allan design, the tug was first named the Gulf Julia. Later renamed the Seaspan Defender it has more than earned its keep over the past three decades towing along the Pacific coast.
But this was a well designed and well built boat and the owners felt secure in doing a routine repower to extend its life.
An old pair of 725 HP engines was pulled out and replaced with the new Cummins KTA38M0 engines. The new engines have been de-rated to 500 HP each at 1600 RPM but are designed capable of 800 HP each at 1,800 RPM. The existing Twin Disc TD540 7:1 marine gears were sent out for rebuilding and reinstalled. The three-blade propellers in nozzles were kept to their original 74 in X7 8 in dimensions.
Shields explains, "We had Robert Allan Ltd. do a complete engineering study for us on the repowering and were amazed to discover that the propellers were an absolute perfect match for the two ratings of the Cummins engines."
The real measure of a tug is pulling power and experienced owners know that translates to earnings. "We didn't do a bollard pull test, but believe we are getting slightly better performance than prior to the re-power. We estimate the bollard pull at 36,500 lb at the 500 hp rating and 57,750 lb at the 800 hp rating," explains Shields.
While the engine selection and preparation was a detailed and intense process, the actual lowering of the two 9,000 pound engines was accomplished in a solid morning of work. A well coordinated team that worked with a rented crane to lower the machinery through a hatch in the top of the fiddley. The engines, lifted with a specially designed jig, were stood on their head to fit through the hatch with inches to spare. The gears followed and were mated to the engines and shafts.
Port Engineer Andy Farmer is pleased with the installation and is looking forward to the operation of the engines with their Eliminator and Centinel options that effectively eliminate the need for oil changes. The two systems combine to reduce operating and maintenance costs while creating an environmentally friendly operating regime. The Cummins-designed Eliminator removes all disposable lube oil filters. The Centinel Oil Management, an oil burn system, works in conjunction with the Eliminator to virtually negate the need for oil changes and costly waste oil disposal.