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How Do You Move a 25-Ton Cannon? Dry Tortugas National Park Found an Ingenious Answer


(Top photo) The restored and remounted Rodman. (Bottom photo) A fallen giant; one of the unrestored Rodmans at Fort Jefferson. NPS photos.

How do you hoist and move a 25-ton cannon? These days, the answer usually involves a crane or other heavy equipment, but those aren't options at one of the most remote national parks in the country. The staff at Dry Tortugas National Park solved the problem with a combination of old-fashioned technology, ingenuity and teamwork.

Dry Tortugas National Park includes seven small islands in the Gulf of Mexico, seventy miles west of Key West, Florida. The site occupies a strategic position on the edge of the main shipping channel between the Gulf of Mexico, the western Caribbean, and the Atlantic Ocean, making it an ideal location for construction of a large military fortress in the mid-19th century.

Fort Jefferson was one of the largest all-masonry forts ever constructed, and although it was never the target of an attack nor fully completed, it served its strategic purpose during a key period of our nation's history.

The fort also includes a "nationally significant collection of 19th century seacoast artillery." According to the park staff, only twenty-five 15-inch smoothbore Rodman cannons are still known to be in existence, and six of them are at Fort Jefferson; four of the thirteen surviving 10-inch rifled Parrott guns are part of the park’s museum collection.

It's fortunate they're still available to help tell the fort's story; these prime pieces of military history were almost lost to the scrap heap.

In 1900, before the fort became part of the National Park Service, the fort’s armament—including these 10 large guns—were sold as scrap. In this case, the park's remote location and the gun's considerable weight proved to be advantageous, and the 25-ton Rodmans and 13-ton Parrotts were left behind.

The gun carriages (the wheeled bases that support the guns) were scrapped, and for over 100 years the cannon lay directly in the salty sand on the fort’s terreplein (the level space behind a parapet of a rampart where guns are mounted). A park spokesman notes that "In addition to leading to corrosion and deterioration of the guns, the haphazard display of cannon on top of the fort did not contribute to visitor understanding of the park’s history or significance."

Members of the park staff realized the importance of remounting at least one of the big guns, not only for the sake of preservation, but also to help visitor visualize how the guns were placed during the fort's heyday. In addition to the usual funding hurdles, there was one major challenge: how to hoist and move the hefty cannon.

The fort’s location prevented use of the most obvious tool for accomplishing the job—a crane, and the gun’s weight and other concerns precluded the use of a helicopter.

So…how did they move a 25-ton cannon?

The answer proved to be a modern adaptation of old technology. Cranes weren't available when the fort was built in the 1800s, so how were the cannon moved in those years? Museum curator Nancy Russell researched historic military manuals, using old methods and equipment as inspiration for modern versions which could safely do the same tasks.

Conservators worked with boat builders and metal fabricators to create these modern adaptations of historic cannon moving and lifting tools. In October and November of this year, visitors to the park were treated to the sight of a 25-ton cannon lifted about 7.5 feet in the air so the carriage could be built underneath it.

The cannon was suspended in the air with a gun lift, inspired by a circa 1876 15-inch Rodman lift designed by Theordore T.S. Laidley and a later modification created by Gulf Islands National Seashore in the 1980s.

Using the modernized moving and lifting tools, it took three men only six days to move and lift the 25-ton gun into position, including assembling the tools and equipment on top of the fort. The carriage was assembled underneath the gun by four men in six days, including bringing all of the carriage pieces, some of which weighed almost 1,000 pounds each, to the top of the fort.

The project, which started two years ago, was completed in November as part of the celebration of the 75th anniversary of the park as a unit of the National Park Service. Funding for the cannon work came from the park's recreational fee demonstration program (entrance fees.)

“A Rodman cannon mounted on an iron carriage hasn’t been seen at Fort Jefferson in over 100 years,” said curator Nancy Russell. “Most members of the team understood the historic significance of what we were accomplishing. With this one project, we restored part of the historic profile of the fort, which would have included mounted guns as a visible deterrent.”

“The biggest challenge of this project was logistics,” said Russell. Dry Tortugas is location 70 miles west of Key West in the Straits of Florida. Without road access, everything has to be brought in by boat. “Detailed planning and flexibility is important because you can’t just run out to the hardware store if you forget something. Safety was always first and foremost when working with such a heavy object, 45 feet up on top of the fort, because medical care is also a long way away.”

“This project, in this remote location, couldn’t have been completed without a lot of amazing individuals working together,” Russell noted. NPS staff working on the mounting project included Russell, who envisioned the project, conducted the historical research, and managed the various aspects of the project; archeologists from the Southeast Archeological Center, who excavated and documented the remains of an original in situ Rodman gun platform; the captain and crew of the MV Fort Jefferson, who transported all the materials and equipment to the park; park maintenance staff who willingly facilitated all aspects of the project; and a number of other staff members at Dry Tortugas and Everglades National Parks.

Before the gun could be mounted on its carriage in the correct location, another key element was required: a reproduction gun platform. Work on the platform was completed by the 482nd Civil Engineers Squadron (CES) from Homestead Air Reserve Base. The unit had been conducting training at the park since the 1970s but due to other commitments had not worked in the park since 2005. Russell worked with Colonel (ret.) Jerry Cheeseman to bring the 482nd CES back to assist with the project.

Due to the physical and technical challenges of the project, Colonel Cheeseman assembled a team of 17 active duty and retired reservists, with the retired reservists serving as trainers and mentors to the active duty personnel, a first in the squadron’s history. The project’s success led to a renewed commitment from commanders at the Homestead Air Reserve Base to continue training exercises at the park which assist the NPS with maintenance and preservation projects.

“All of these individuals working together have left something behind which dramatically improves the fort,” Russell said. “Visitors, for generations to come, will have a better understanding of the park’s significance. It’s a wonderful present to the American people for the park’s 75th anniversary.”

The park was originally designated as Fort Jefferson National Monument in 1935 by President Franklin D. Roosevelt, who visited the area by ship. In recognition of the area's pristine natural resources and unique historical values, the area was established as Dry Tortugas National Park in 1992.

Information to help plan a visit to Dry Tortugas National Park is available on the park website.

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Are there any photos of the process and equipment used? T'would be very interesting to see them.

Lee -

I haven't had a chance to verify the link, but according to the park, "To see images of this equipment in use and documentation of the entire project, visit “South Florida Collections Management Center” on Facebook."

Thanks, Jim.

Here are a couple of youtube videos showing the work:

Fort Jefferson Part I:

Fort Jefferson Part II:

The project is documented on Facebook. Search for "South Florida Collections Management Center" and you'll find information about the museum collections for the 5 South Florida Parks. There is a photo album called "DRTO Cannon Mounting" which has pictures of the entire process. There is a also a short video clip of the cannon being moved.

Is there maybe a link to a page with photos of the gear that was used? I'm assuming that sheer legs, braces, chain hoists or block and tackle were used.

Sorry about that, when I first viewed this, none of the comments from Dec. showed for me. I love it when the internet makes me look like an idiot.

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