Page 36: of Maritime Reporter Magazine (July 2015)

PROPULSION CASE STUDY

Specialty Motors Keep Shipping A? oat hen large specialty motors fail at sea, ? nding a suitable

Wreplacement within days – not months – is critical to bring produc- tion back online and minimize loss of revenue

Whether for sophisticated thrusters or naval weaponry, or equipment such as compressors, winches or pumps, large specialty motors are used throughout the marine industry. So when one of these motors fails at sea, the rami? cations can range from minor annoyance to com- plete shutdown, which can prove costly in time and money.

This was the scenario that Sealion

Shipping Ltd. faced when its aft star- board azimuth thruster failed in the wa- ters off Mexico, rendering the vessel’s dynamic positioning (DP) system inop- erable.

As a provider of onshore, offshore and subsea support to the oil and gas indus- try, each support vessel in the ? eet uses

DP to carry a diverse range of equip- ment, cargoes and personnel to offshore drilling rigs and platforms. DP requires the use of the azimuth thrusters along with sophisticated GPS reference and other sensors.

So when the aft starboard motor failed, the support vessel could no longer oper- ate in DP. This threatened to take the vessel of? ine, potentially at signi? cant loss of revenue, and would require an expensive and lengthy repair before the ship was fully operational again. motor. Allis stocks used and surplus specialty replaced. Sealion Shipping did not have

For Sealion Shipping, the ? rst priority Founded in 1901 as a DC motor manu- motors it has purchased and refurbished. construction drawings of the motor on was to keep the ship in operation – and facturing ? rm by Milwaukee business- This includes taking the motor com- hand, so instead videotaped a series of earning revenue – until the motor was re- man Louis Allis, the company soon pletely apart, cleaning it, replacing the measurements of various aspects of the paired. As an interim measure, a tug was shifted to AC motors. Facing stiff com- bearings, varnish coating the windings, motor, as well as the mounting details.

employed at some cost to help maintain petition from early motor giants such rebalancing, reassembling and conduct- With this information, Louis Allis the vessel’s position. as GE and Westinghouse, the company ing sophisticated testing. These units are custom remanufactured the motor so it

Sealion Shipping then contacted the decided to focus on specialty motors in- ready for delivery at a moment’s notice. could be a drop-in replacement. This in- motor manufacturer and was told it stead of mass-produced offerings. Before it could be shipped and put into cluded ensuring that it would physically would have to be removed and sent to Today, Louis Allis manufactures spe- use, however, the motor required a num- ? t through a hole cut into the deck of the a central repair facility in Europe, with cialty motors up to 20,000 hp, along with ber of modi? cations. ship.

an estimated ‘out of service’ timeframe standard NEMA motors, in-stock recer- The motor was air-cooled, an issue that The replacement motor was shipped from four to ? ve months. ti? ed units, and motor repair services. would increase the temperature within by Louis Allis and arrived within the 10 “That was not a situation that we Fortunately for Sealion, Louis Allis the engine room. Sealion Shipping pre- days.

could live with,” says a spokesperson had a 3,500 hp motor in its inventory ferred a water-cooled unit, but that was “They managed to locate a suitable for Sealion Shipping. “Meanwhile, we that could be delivered within the 10 not possible within the time requirement. replacement motor very quickly, within turned our attention to ? nding a compa- days it would take the vessel to return The temperature problem was manage- a few days,” says Sealion Shipping’s ny that could supply us with an alterna- to port. Although the main propulsion able, however, and plans were made to spokesperson. In addition, Sealion tive motor very quickly.” motors were two-speed, the replacement convert to water cooling at a future date. tapped Louis Allis to repair the failed

During the search for a solution, was single-speed. Fortunately, it was ad- Perhaps the most dif? cult modi? cations motor. Once the repairs were complete,

Sealion contacted the Louis Allis Com- equate for the DP and the ship’s maneu- involved converting the standard NEMA the installation would occur during fu- pany, which for more than 110 years has vering capabilities. (American) motor to ? t the metric speci- ture scheduled maintenance or dry dock. www.louisallis.com manufactured and repaired this type of To facilitate speed of delivery, Louis ? cations and footprint of the motor being 36 Maritime Reporter & Engineering News • JULY 2015

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