Archivist’s Attic – The Wonder Arches

Curveballs – The Wonder Arches

Sometimes instructions are just a suggestion, in the case of the Seabees often time’s items will be designed or manufactured with ideal conditions in mind. That’s great, as long as the items are always being produced in the same way. Life loves to throw us curveballs and in the case of the Seabees, curveballs are a way of life.

The Wonder Arches were originally designed for use as unground passage ways and storage areas in Antarctica. They worked so well that the Seabees decided to bring them over with them to Vietnam where they came into widespread use as aircraft shelters. Although the structures themselves are standardized, the locations are not, creating curveballs of problems. It became evident that the manufacturer’s instructions were only guidelines and the trial-and-error method to devise a workable construction procedure for a specific job site and climate conditions were necessary. Some of the more interesting methods used involved changing the directions for the lift, ladders and pins!

Lift – Less is More

The manufacturer suggested that three two-foot arches be assembled on the ground and lifted into place by a crane. However it was found by the Seabees that fabrication of two-arch assemblies was more advantageous sense the panels can be handled by two men with relative ease for ground assembly of the second arch to the first.

Not only is manual manipulation quicker and easier, but the ground fabrication of the second arch to the first arch is much easier that the fabricating the third arch to the second arch. This is due to the weight of the third arch on the first and second arches causing them to bend somewhat, making the hole alignment much more difficult. Even more important is the fact that the two-arch assembly, when being erected, is little more flexible than the three arch assembly thus facilitating erection and preliminary bolt-up

Seabees with NMCB-121 pour concrete to form a protective cover for a Wonder Arch aircraft shelter for Marine Aircraft Group 16, located in Military Region I, Republic of Vietnam.

Seabees with NMCB-121 pour concrete to form a protective cover for a Wonder Arch aircraft shelter for Marine Aircraft Group 16, located in Military Region I, Republic of Vietnam.

Ladders – Don’t Swing on the Ropes

In order to get up to the arches to finish bolting them together rope ladders were provided by the manufacturer and were intended to be used by the man on top of the erected arch, working with another man inside the arch on a scaffold. However, the curveball though was the climate and heavy rain which led to rapid deterioration of the rope ladders and prompted a search for more effective methods. Several types of ladders and scaffolding were tried, but finally a system using a block and tackle with a boatswain’s chair proved to be the most successful.

By fairly simple maneuvering the crewmen were able to reach four or five sections before having to move the suspension system, thus saving considerable time and resources.

A 3-rib section of a steel "Wonder Arch" aircraft shelter is being lifter into position on a parking apron at the DaNang Air Base. Seabees are from NMCB-3.

A 3-rib section of a steel “Wonder Arch” aircraft shelter is being lifter into position on a parking apron at the DaNang Air Base. Seabees are from NMCB-3.

Pins – Make it Yourself

After the arches are up and there is a system in place to work from all that’s left to do is put the pins in place to hold the whole thing together! The manufactures packaged the steel panels in a way to prevent damage. The curveball was by the time the panels got to the Seabees a majority of the panels were bent and deformed. The pre-drilled holes in the panels and arches seldom lined up without liberal use of drift pins, supplied by the manufacturer to force them into alignment. The stresses placed upon the pins in this manner caused them to bend and crack prematurely.

To combat this problem the Seabees themselves, manufactured replacement pins out of stainless steel, which proved to be more durable. Saving the structures and enabling the arches to finally be bolted together.

The Seabee’s ultimately found that by using the manufactures instruction manual primarily as a guide, they could take those curveballs that were pitched to them, put a little elbow grease into them, change the direction and hit them out of the ballpark.

Now that’s using Seabee ingenuity to hit a home run!

150225-N-JU810-001Meet the Archivist: Ingi House
Ingi House is originally from Kansas where she got her B.A. in history from K.U. and M.L.S. from E.S.U. After working for the Dole Institute of Politics she moved to the East Coast.  In D.C. she worked at the National Archives and Records Admiration and then at the Defense Acquisition University where she became a Certified Archivist. Her continued enjoyment of military history lead her to switching coasts and coming to work for the Seabee Museum where she is collection manager for the archives and records manager liaison.

One comment on “Archivist’s Attic – The Wonder Arches

  1. Robert Gallinari says:

    Very interesting

    Like

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