Navy Seabee Foundation

Pontoons — Magic Boxes Nothing Short of a Miracle

Pontoons – Magic Boxes Nothing Short of a Miracle

March 1, 2016

by CEC/Seabee Historical Foundation

This week we’ll discuss the “secret weapon” of the Navy — pontoons. They came to be called “magic boxes” and were nothing short of a miracle. A simple steel box which helped lead the way to victory during WWII.

By 1943 the U.S. was immerged in war on two fronts; the Atlantic and the Pacific. Thousands of men, trucks, armament, and equipment needed a fast and efficient way to offload from ships, most often under enemy fire.

1. Capt John N. Laycock demonstrates his miracle box for Admiral Ben Moreell, chief of the Bureau of Yards and Docks. (1943)

2. A rhino ferry of assembled pontoons married to an LST during the Normandy invasion. (1944)

3. Crane on top of a pontoon being used to dredge a lagoon. (1943)

A frequent challenge surrounded the LST’s, which were vessels that could drive their ramps clear to a beach and offload machines with no time lost. Unfortunately, many of the LST’s were getting stuck in the water hundreds of feet before reaching the beaches causing equipment to drive off the ships and become submerged.

The task of finding a solution to this dilemma was given to Capt. John M. Laycock, Naval Civil Engineer Corps, pictured above with Adm. Ben Moreell. He derived the idea of the “magic box.” He had discovered a way to string the 5 x 7 x 5 foot pontoon boxes together and keep them strung rigid and capable of sustaining great weight in a heavy sea. Placing two pontoons side by side and thirty deep, they strung together to create causeways which could attach to the LST’s ramp and offload thousands of men, trucks, and all their equipment to shore within minutes of landing.

Seabees, whose jobs mostly consisted of land construction of airstrips, roads, and oil tanks, were then able to engage in sea operations. The Seabees were responsible for the operation of the pontoons and the transport of men and equipment from LSTs.

What is fascinating about the concept behind pontoons is not only could they create causeways, but when fastened together in different capacities, they took numerous other forms! To name a few, pontoons could assemble into self-propelled barges also known as “rhino ferries,” floating dry docks, seaplane ramps, floating cranes, and pontoon bridges.

New useful combinations were constantly being discovered and each combination contributing to the victory of the war.

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  1. I was a member of the 111th NCB Battalion Company B.We made the landing at Omaha beach Normandy with a load of Sherman tanks. I believe we had 10on board, and we hit the beach at 0600hrs. The barge worked great. It was amazing how well they worked and how much weight they could carry.

    • Dear Mr Illiamsom

      I would love to directly contact you ref your time with 111 NCB, especially with regards your time in Cornwall/Devon prior to D-Day…which of the pontoon construction yards were you with – Falmouth, Dartmouth or Plymouth ?

      Thanking you in anticipation

  2. 1943-1945 Banika,Russell Island I was there- PAD 1&2

  3. I have never thought of pontoons as miracle boxes. However, I also didn’t know that they made such a difference in WWII. Thanks for posting and pointing this out. I will be looking at my pontoon dock and boat differently from now on.

  4. Great idea, but how did they work, and are we still using them?
    Can’t seem to find out.

  5. It was based on the dimensions of a Cigar Box. Captain John N Laycock was my great grandfather. I have more information if you would like. I still have some of his work papers from this project among others. Maren Laycock DeWeese