Rescued USS Monitor steam engine returns to Civil War appearance

Photo Sangjib Min - Daily Press

By Mark St. John Erickson - Daily Press

When Navy divers and NOAA archaeologists recovered the USS Monitor steam engine from the Atlantic in 2001, the pioneering Civil War propulsion unit was enshrouded in a thick layer of marine concretion.

Sand, mud and corrosion combined with minerals in the deep Cape Hatteras, N.C., waters to cloak every feature of Swedish-American inventor John Ericsson’s ingenious machine, and they continued to envelop the 30-ton artifact after nine years of desalination treatment.

Just this past week, however, conservators at The Mariners’ Museum and its USS Monitor Center drained the 35,000-gallon solution in which the massive engine was submerged and began removing the 2- to 3-inch-thick layer of concretion with hammers, chisels and other hand tools.

Working slowly and carefully to avoiding harming the engine’s original surface, they stripped off more than 2 tons of encrustation in their first week of work alone, gradually revealing the details of a naval milestone that had not been seen since the historic Union ironclad sank in a December 1862 storm.

“This is a technological marvel. It was cutting edge in its day. But what’s really neat is revealing all the wheels, oil cups, valves and other parts that the Monitor’s crew used to operate the engine,” said conservation project manager Dave Krop.

“If you consider that it spent nearly 139 years underwater, it’s in outstanding shape — though some of the wrought iron has seen better days. And there are some copper alloy parts that look brand new when they’re first uncovered — like they just came off the shelf.”

Smaller, more compact, yet just as capable as other steam engines of its day, the Monitor’s vibrating side-lever engine was the ideal match for Ericsson’s revolutionary warship.

Its long, low, horizontal cylinder enabled the engineer to place it below the vessel’s waterline as well as behind a thick armor belt — and that well-protected position virtually eliminated the vulnerability associated with the much larger and more easily targeted engines of the day, most of which towered above the ships’ decks.

So confident was Ericsson in his engine’s capabilities that he ignored orders to equip the vessel with masts and rigging.

And it astounded Union and Confederate observers alike with the way it performed in its historic clash with the rebel warship Virginia — also known as the Merrimac — in the March 8, 1862 Battle of Hampton Roads.

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