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PLANTPRACTICES
The USS Nimitz is one of the Navy’s nuclear powered aircraft carriers classified as a super carrier and the lead ship of its class. With a displacement of 100,000+ tons, a length
of 1,000+ feet, a 4 acre deck, a crew 5,000 strong, and only two
locations in the world that can handle its dry dock maintenance
needs, the carrier needs to schedule maintenance activities over two
years out.
The Challenge
Christopher D. Gates, the Assistant Reactor Maintenance Officer,
was tasked with improving a maintenance schedule system both in
port and at sea for the USS Nimitz’s power plants. Says Gates, “The
problem I was trying to solve was level loading the over 26,000
tasks I receive from the preventive maintenance program, along with
the immediate 5,000 corrective maintenance jobs that are outstand-
ing. Both sets of tasks rely on common resources and I needed an
easy and reliable method to level load and schedule (tasks) accord-
ing to priority and finite capacity.”
The maintenance and production demands came from disparate,
proprietary databases which, due to security restrictions, could not
be combined or integrated. The schedule extended two years out to
accommodate dry dock cycles plus the maintenance inventory had
to accommodate at-sea schedules averaging four to ten months.
Gates was trying to schedule this data using ten separate master Excel files.
Microsoft Project
was used for Gantt
charting, but was
difficult to handle
with all the importing and exporting
requirements.
Attempts with
other systems still
left Gates without
capacity considerations.
Implementation
was urgent so it
would need to be
easy and familiar
enough for rapid
adoption by some
400+ sailors. By
leveraging Excel,
Gates could avoid the required military quarantine and testing secu-
rity process for proprietary systems.
The Solution
“I found User Solutions while searching the internet for Finite
Capacity Scheduling and ERP systems based in Excel,” Gates
explained. “As soon as I started using their product Resource
Manager for Excel (RMX), I could tell the flexibility of their prod-
uct would be beneficial working with an at-sea schedule which
changes almost by the hour.”
RMX from User Solutions is a resource management planning,
scheduling, and tracking system that can perform intricate finite
capacity scheduling combined with level loading and material
requirements planning. Yet, with all that sophistication typically found
in costly, cumbersome, and rigid systems, RMX has preserved all the
integration options, flexibility, and analysis that are inherent in Excel,
not to mention the rapid calculation speeds.
The new expanded version of RMX – v2014 – leverages the
expanded version of Excel 2013, and supports 1,000,000 rows of
data and 16k columns per sheet. This was perfectly positioned to
accommodate the Nimitz’s needs.
“RMX is one of the fastest, if not the fastest, finite capacity scheduler combined with materials requirements planning (MRPII) due
to its leveraging the speed with which Excel performs mathematical
Software Schedules Maintenance
With Military Precision
In this month’s Plant Practices, we take you offshore to a military
application, where best practices around maintenance scheduling
and planning can offer manufacturers some ideas.
By Christopher D. Gates, Asst. Reactor Maintenance Officer on the USS Nimitz
