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Rowan/OEM to Build New Corps Dredge

The dredge on Lake Wildwood in 2003.

The dredge on Lake Wildwood in 2003.

Rowan Electric, Inc. (dba Oilfield Electric Marine -- OEM) will build a 20-inch cutter suction dredge to replace the Dredge Thompson for the Corps of Engineers, St. Paul District.

The company was awarded the $9,837,500 contract by the Philadelphia District Marine Design Center on September 30, with an expected Notice to Proceed at the end of October, 2003.

All of the dredging machinery, including pumps, cutter and winches, will be driven by AC vector drives and motors. The main dredge pump is powered by two 1500 hp OEM Double T Hi-Torque AC electric motors and variable-frequency drives. Two Caterpillar 3516B engine generators will supply dredge's power.

A low-usage hydraulic spud travel system will use environmentally friendly oil.

"Using all state of the art AC electric drives, we packaged the dredge competitively in price compared to older technology," said Patrick Williams, OEM business development manager. "We can electrically power the winches, (eliminating hydraulics) which means no oil spills and less noise," he said. (Williams is no relation to Kevin Williams, president of OEM.)

"We elected to run the generators at a low 1200 rpm, increasing the longevity of the engine, and producing less noise, with fewer emissions," said Williams.

"The generators will be housed in a soundproof compartment, so the whole dredge is quieter," he said. "This, I believe, is what sold the Corps on our ideas. We've gone the extra step."

Peter deJong, DACS, Inc. will serve as engineering consultant, and design the mechanical components of this dredge.

DACS automation will provide dredge automation including flow control, anti-plugging valve and booster telemetry, OEM has given the Corps the option for swing and ladder control. . The contract includes an 1800hp self-contained booster pump, which will give the dredge a total pumping distance of 10,000 feet. The booster telemetry system will allow the operator to fully control and monitor all of the booster's functions. Once the booster is set on Auto-Run it will run automatically, responding to changes such as varying load.

The hull and outfitting will be accomplished at OEM's sister company LeTourneau, Inc's. shipyard in Vicksburg, Mississippi.

The dredge's approximate dimensions are 200'x 39'x 8' displacing 1400 tons.

Rowan Companies is a drilling company that has been in business since 1927. Two years ago they purchased Oilfield Electric Marine and expanded the company, which now operates from a 300,000 square foot facility on the Sam Houston Parkway North, Houston, Texas.

The combination of OEM's background in providing the dredging industry with electrical components and turnkey systems, combined with LeTourneau's heavy fabrication operation gives the company the ability to produce turnkey dredges, and the new Corps dredge will be first of the new line of Neptune 20 models to be built.

The company also hired Patrick Williams to help develop new business for OEM and LeTourneau.

Williams was with the Panama Canal Dredging Division for 25 years, from 1975 to 1999, where he was chief engineer of the dredges Mindi and Christensen, fleet engineer (port engineer) of the Dredging Division, and marine inspector of transiting vessels as well as the dredging contract officer representative.

He joined Rowan in 2001, and has concentrated on the dredging industry, developing turnkey dredge electrical component systems, most recently providing an electrical enclosure for a mining dredge with an AC750 hp ladder pump motor and drive, medium voltage transformer, switch and controls.

He worked with OEM's engineering design team to develop the specification and design for the Corps dredge. Williams lives in Birmingham, Alabama.

Specifications: St. Paul District dredge:
Pump - 20"x 22"x 54"
Digging depth - 25'
Cut width at 25' depth - 280'
Walking spud travel - 18' (minimum of three cutter lengths)
Cutting force- 24,000 lbs
Cutting hp - 302 hp
Swing line pull - 53,000 lbs @ 80fpm
Wire rope Safety Factor - 3:1 min
Gearbox Service Factor - 2 min
Draft - 6' max.
Air draft - less than 45'
Overall beam - 39'
A five miles per hour river current and 30 mph wind were used for calculating swing line pulls to exceed 1.5 times cutter blade force. Extreme condition calculations use 80 mph and five mph as simultaneous forces.

Delivery date is approximately 400 days from award of the contract. A committee of St. Paul District employees is discussing names for the dredge and an accompanying work boat, said Dan Krumholz, of the Channels and Harbors Division at the St. Paul District. Anyone can submit proposed names, and the final decision will be presented to Corps headquarters early next year, he said.

The bid abstract on the job, which was a negotiated, best value procurement, is as follows:
Eastern Shipbuilding Group: $9,353,695
Ellicott Division, Baltimore Dredges LLC: $9,722,500
Rowan Electric, Incorporated: $9,837,500 (Proposal I)
Rowan Electric Incorporated: $9,822,000 (Proposal II)
Bay Shipbuilding Company: $9,952,000.

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