Martinac Shipbuilding reports IPS-designed switchboard is an electric plant “technical marvel” for Signet Maritime’s new Z-drive escort tug boats America and Pacific Star

(Jacksonville, FLA. – August 7, 2008) -– Owners and operators of new state-of-the-art tug boats recently built by J.M. Martinac Shipbuilding Corp. of Tacoma, WA, are collectively praising the innovative electrical control system designed and built by Industrial Power Systems, Inc., (IPS) of Jacksonville, Florida (

Built for Signet Maritime (Houston), the new $12 million Z-Drive “tractor tugs” America and Pacific Star are leased to Foss Maritime (Seattle) for its ship assist and tanker escort business. The second vessel, Pacific Star, was handed over by the builder J.M. Martinac Shipbuilding Corp. in June.

Industrial Power Systems, Inc. was asked by Martinac to apply their controls wizardry to design and build generator power management systems for the new state-of-the art Z-drive tugs. The result is a “technical marvel” that “solves a notorious problem encountered in design of electric plant on tug boats”, says Gary Farrell, Martinac Shipbuilding’s chief electrical designer.

Ship service generators, operating 24/7, should be sized to work at their highest continuous load levels. This translates into better fuel economy and improved O&M (Operations and Maintenance) costs for the owners. But tugboats are far more demanding applications. The normal ship service load on the tugboats America and Pacific Star is 70 kW. However, for just 15 minutes every day they each operate a 56 kW hawser winch. A generator sized for both loads would provide ideal operating conditions only 15 minutes each day, and 55% full load for the rest of each day – severely compromising fuel economy and long-term O&M costs.

To resolve the generator-sizing dilemma, IPS’s challenge was to design and build a fully-automatic power management system to operate a 99 kW generator at optimal 70%+ load factor all day and automatically load-share with a standby 99 kW generator to power the hawser winch and all necessary loads during winch operations. And in the event that the 2nd generator is not available automatically shed preselected loads to power the hawser winch when required.

Delivered on schedule, IPS’s innovative power management system is what Mr. Farrell terms “a technical marvel … the customer is absolutely thrilled with the switchboard and all the tricks it can do, and the Foss engineers who are operating the first vessel think it is the neatest thing since sliced bread.”

Joe Dahl, formerly Signet Maritime now general manager of production at Martinac, said “I’ve never seen anything like it before. I used to work on a dredge and we’d have to wait to manually synchronize a second generator and add loads before doing the job the IPS switchgear does seamlessly and automatically, even with one generator.”

Joe Martinac, president of Martinac Shipbuilding said the power management system is “Nicely engineered system that works like a charm, and we got great support from IPS.”

By Professional Mariner Staff