The unusual concrete barges that rest on the Thames and were used in the Normandy landings

One of the many legends that tell of the arrival of the Apostle Santiago to the Iberian Peninsula says that he arrived on the coast of gallaecia crossing the Pillars of Hercules by boat and then going up the Atlantic; another version tells that there were actually seven disciples moving his body.

In any case, the most fantastic thing about the story is that the trip would have been made in a stone boat. It surprises even within its mythical tone because nothing seems more absurd than sailing in a boat made of that material. Now, what if I tell you that there is a shipbuilding technique that makes concrete boats?

If one visits London and approaches it by following the Thames to the so-called Section 24 of the London LOOP, between the towns of Rainham and Purfleet (in the eastern part of the capital), one will find a most unusual corner: on the bank of the river , grouped in a certain disorder on the wet and grayish sand, there are sixteen large boats that seem to sleep in oblivion, covered in mud and rust. Approaching them you will discover with surprise that this small flotilla has a very special characteristic.

The group of barges, from a bird’s eye view / Image: Google Maps

Those who have arrived by car will already have a clue because the parking lot that is right there -in fact, enabled to be able to stop to see the site- is called The Stone Barges. Translated, The Stone Barges. It is not a monument, at least in the sense that is usually given to that word, because the boats have not been carved by a sculptor; nor are they the fleet of a saint, if I may. His story is much more recent than Santiago’s. And harder.

Because the sixteen ships were built during World War II for the famous Normandy landings. What’s more, these are only a small part of the dozens that were made and that, as I said before, have a singularity: they are not made of stone but they are made of reinforced concrete. I emphasize, it is not that they were dedicated to transporting concrete but that their hull is made of that material so rare in the naval world. Although surely more than one will be caught with the wrong foot, concrete boats are lighter than water and float.

Construction of a ship with a concrete hull/Photo: public domain on Wikimedia Commons

Reinforced concrete has been used to build ships since the 19th century. The oldest documented case dates back to France in 1848, to the credit of Joseph-Louis Lambot, inventor, after all, of the material itself. This was applied -in the maritime field- to river barges fundamentally and only at the end of the century were ships made that went out to sea; the Italian Liguria of the engineer Carlo Gabellini, was the most famous. From then on, the technique was spread and generalized because of how cheap it was, although in return its construction was more complex than that of normal ships.

In the interwar period, the technique of reinforced concrete boats was abandoned as better materials were found, even cheaper and easier to treat. However, in 1942 the difficulties of the conflict and especially the shortage of steel forced to recover it.

Twenty-four non-engine barges designed to be towed were built in the US; A concrete submarine was even projected (!) although it never came to fruition, just as the making of larger ships did not prosper.

An American barge/Photo: Public Domain on Wikimedia Commons

Since steel had to be reserved for combat ships, for cargo ships they opted for concrete on an iron skeleton, which was much cheaper and more available. On D-Day they were first used to transport fuel and ammunition to ships; later as transport of soldiers, breastworks on the beaches, mobile canteens and finally pontoons of the Mulberry ports.

The Mulberry ports, so named because they looked like blackberries, were artificial infrastructures that were improvised on the French coast to facilitate the work of unloading equipment and disembarking soldiers, once the beaches had been taken. There were two: the American Mulberry A from Omaha Beach (lost to a storm) and the British Mulberry B from Arromanches (of which remains remain). The boats, which were popularly called as beetles (beetles), although its technical name was corncobs (cobs), served as piles to support the docks, known as whales (Whales).

Arromanches Mulberry B in 1944/Photo: public domain on Wikimedia Commons

If some of the surviving whales were later reused to repair bridges destroyed in bombings, at the end of the war most of the ears ended up at the bottom of the English Channel or in other depths, since they were also used on the Pacific front. , where they later had a secondary use as macro-refrigerators to keep food refrigerated in the face of high temperatures; apparently they could maintain about twelve degrees thanks to a freezer motor.

There are units scattered around the world: New Jersey, Cuba, Galveston, Ireland, Scotland, California… In Holland they are still manufactured as floating houses and in the Powell River (British Columbia) a group of them serves as breakwaters; but perhaps the most interesting, due to their curriculum, are the sixteen from the Thames: in 1953 they were brought back to England to be anchored in its course and serve as flood barriers.

They have remained there since then, having also acquired an extra utility: that of lodging for the nests of waterfowl.


Ships for victory. A history of shipbuilding under the US Maritime Commission in World War II (Frederick C. Lane)/How water influences our lives (Per Jahren and Tongbo Sui)/Amazing World War II Stories (Jesus Hernandez)/Victory Engineers. The men who changed the fate of World War II (Paul Kennedy)(The Normandy landing. The key D-day for the allied victory in World War II (Ed.