Murk Lels arrived in the Smit family with a sailor's eye and a merchant's ambition. He had gone to sea at fourteen, swallowed the anchor at twenty-two, and by his twenties was managing nine ships totaling 7,248 tons on the Dutch East Indies route. Marrying Ottolina Smit in 1846 plugged him into a clan of shipbuilders. He repaid the favor by routing his orders to his in-laws. Over the next two decades J. & K. Smit launched a steady procession of barques for him: Kinderdijk, Cornelis Smit, Otto, Ottolina, Johanna en Geertruida, each carrying a family name into the South China Sea. Murk also moved on to Yokohama, where in 1864 he founded the trading house that became Carst, Lels & Co., one of the early European firms in newly opened Japan. He even founded a coffee company at Banyuwangi on Java. The shipyard at Kinderdijk was his back office, half a world away.

By the 1880s the great age of Dutch ocean sail was ending, and J. & K. Smit had the sense to see it coming. In 1878 they delivered Adam I, the first Dutch self-loading suction dredger, to the contractors building the new locks at IJmuiden. It was such a hit that Adam II followed the same year for work on the Nieuwe Waterweg, the deep channel cut to connect Rotterdam to the sea. The French government ordered three of the things in 1883. By January 1886 the shipyard had completely retooled: every vessel on the slipway was a dredger, including one going to South Africa, one to Japan, and one to the city of Utrecht. The Japanese dredger had to be disassembled after launch and shipped abroad in pieces. Holland's land-from-water expertise, born of necessity, had become an export product. By the end of the century, dredgers from Kinderdijk were digging harbors in Argentina, Australia, Denmark, Russia, and along England's River Wear, the last won on price against local British shipbuilders by a margin of more than 3,000 pounds.

Among the hundreds of tugs J. & K. Smit launched into the Lek, one carries a second life worth pausing over. On October 14, 1958, the yard launched the Elbe, a sister to the seagoing tug Clyde delivered the previous year. She was the thirtieth tugboat off the line for the family's tug-service partner L. Smit & Co. Decades later she was sold to a young environmental organization and rechristened MV Greenpeace. Her sturdy Kinderdijk-built hull absorbed years of confrontations with whaling fleets and nuclear test sites. After her activist career ended she was renamed Elbe again, and today she sits as a museum ship at Maassluis, a few kilometers downriver from the yard that made her. The same shipyard also built, in 1962, the fourth tug to bear the name Zwarte Zee. At her launch she was billed as the biggest, fastest, and most powerful tug in the world.

The dredging specialty branched in unexpected directions. In 1926, J. & K. Smit built a tin-bucket dredger for the government mines on Bangka Island, off the Sumatran coast. More followed. The Sergang and the Soerabaya went to the Singkep Tin Company in 1927. The Weltevreden was sent to Bangka in 1928 for the Tinbagger Maatschappij. These were strange, floating, factory-like machines, scooping the tin-bearing sands of Southeast Asian rivers into onboard separators. They were also extraordinarily profitable. When the Great Depression hit, the shipyard survived the lean years partly because its tin-dredger expertise kept finding customers in colonial mining outposts. By 1939 the launching of the great tin dredger Doejoeng marked the recovery of the market, just months before the war shut everything down.

After the Second World War, six dredging shipyards in the Netherlands looked at each other, looked at their post-war order books, and concluded they could not afford to compete with one another. They formed the Industriële Handels Combinatie, IHC for short. J. & K. Smit was in. So was L. Smit en Zoon, the cousin-yard down the same Lek riverbank. The two would slowly fuse. By 1966, the year after IHC formally became a single company, the boards merged the J. & K. and L. Smit shipyards into a partnership called Smit Kinderdijk. The names that had marked separate empires for more than a century became letters on the same letterhead. The modern shipyard that occupies the site today, part of Royal IHC, still contains the original brick buildings, but they are completely surrounded now by newer halls. From the river, you can no longer see exactly where one Smit ended and the next Smit began.