Shipbuilding innovations evolved slowly in the 18th century. New naval architects started their careers apprenticed to shipwrights who used methods of construction unchanged for decades. But, under the pressure of increasingly long wars and the demand for larger ships, a new breed of innovators came to the fore. The most important was Robert Seppings.
Seppings was born in 1767. He grew up in rural Norfolk, the son of a cattle dealer. After his father died in 1781, he lived in Plymouth with his uncle, a retired navy captain. The young Seppings was fascinated by the huge warships that dominated Plymouth Sound. Seeing Seppings’ enthusiasm, his uncle used naval connections to apprentice his nephew to Master Shipwright John Henslow at the Royal Dockyard at Plymouth. Seppings took to his new profession with gusto.
Seppings was fortunate to work for Henslow. Eighteenth-century shipwrights were a conservative breed, but Henslow was more open to new thinking than most. Henslow had been apprenticed to the great Sir Thomas Slade, who had designed most of the Royal Navy’s best warships, including Horatio Nelson’s Victory. Perhaps seeing some of his old master’s brilliance in Seppings, he encouraged his young apprentice and promoted him over more pedestrian colleagues.
Seppings’ first break with tradition came in 1800, when he devised a radical new method for securing ships in dry dock, replacing the laborious process of lifting that had been the norm for centuries. His invention—later called “Seppings blocks”—was a row of supports placed on the floor of the dock, each one made from three parts to aid easy removal. The hull rested on these until it was suspended on shores, at which point the blocks were knocked away, giving the workmen free access to the whole keel. It was quickly adopted throughout the shipbuilding industry and was considered so valuable a grateful Admiralty rewarded him with a gift of £1,000.
In 1803, the post of master shipwright at Chatham became vacant. Seppings’ old master was now Sir John Henslow, Surveyor to the Navy, responsible for all the Royal Dockyards, including Chatham. He took the opportunity to again promote his former apprentice over the heads of several veteran candidates. Seppings was 35, by far the youngest man to be promoted to such a senior position. It proved to be an inspired choice.
Chatham was one of the most important Royal Dockyards. Built there were many of the navy’s most famous ships, including the Victory. Seppings took over when Britain was locked in a naval arms race, Napoleon having ordered new warships to be built in every European shipyard from Holland to Venice at a pace the Royal Navy struggled to match.
One of the first issues Master Shipwright Seppings had to deal with was a shortage of timber. Building a new 74-gun ship-of-the-line required more than 6,000 mature trees, mainly oak. In an age before railways, the trees therefore needed to come from forests close to a navigable waterway. After more than a century of naval warfare, the supply of local oak was becoming exhausted, slowing the rate at which the dockyard could operate. Seppings addressed this issue by doing things none of his predecessors had done.
His first innovation was to make better use of what was available, reusing old but sound wood from broken-up ships to supply the timber for noncritical areas of new ships. He then used the Navy’s global connections to scour the world for promising alternatives to English oak. He experimented with several different types of hardwood, including North American oak, Cape Yellow timber from Southern Africa, mahogany from the Caribbean, teak from India, and African stinkwood—which, despite its unpromising name, worked very well. To get a warship back into service, almost any expedient would do, including in one case planking a frigate’s deck diagonally when he lacked the necessary long runs of timber to do it fore and aft.
The timber shortage also prompted Seppings to embark down a path that would ultimately lead to the end of wooden ships altogether. Early in his tenure at Chatham, the Tonnant (80 guns) and Culloden (74 guns) were lying idle for want of suitable oak for new knees. A knee is a right-angled timber that supports a ship’s deck, transferring its weight to the hull. It is particularly important in a warship, because of the weight of the ship’s armament. Shaped from a single piece of wood, it is awkward to source. Seppings’ solution was to make knees from metal, a startling idea. The repaired Tonnant and her iron knees would go on to fight with distinction at Trafalgar. As his career advanced, Seppings began to replace more wood with iron as his designs progressed, a process that did much to usher in the next phase in warship construction.
Seppings battled more than the timber problem. He believed ship designs had a fundamental flaw. Traditional ship construction used vertical ribs, called frames, attached to a keel and covered with horizontal planking, with the internal decks providing rigidity. Such hulls were strong in the center, but the ends were much weaker. This resulted in the problem called hogging.
Hogging occurs when the ends of a hull droop relative to the center, arching the ship like the back of a pig. It happens because, beneath the water, a hull has the greatest volume amidships, providing plenty of buoyancy. But it has much less where the hull narrows to form the bow at one end and the swim leading to the rudder at the stern. This problem is exacerbated by the strain put on the ends of a ship by the weight of the stern superstructure and the bowsprit. As warships were lengthened to carry more and heavier armament, the hogging problem became progressively worse.
In May 1805, Seppings was pondering how best to rebuild the Kent, a large 74 that suffered badly from hogging when the Leiden, a Dutch-built ship-of-the-line, was brought into Chatham. A prize captured in 1799, she had been a one-off experimental design by William May, the Dockyard Superintendent of the Amsterdam Admiralty. Examining her hull, Seppings noticed a system of diagonal timbers sloping backward in the ship’s fore body and in the other direction in the after part. He realized immediately they were transferring load from the ends of the hull toward the center. Here was something that might be developed into a solution for hogging.
He introduced similar diagonal bracing into the Kent, but he was limited in what he could in what was only a refit. Meanwhile, he developed his ideas, producing a complete system of diagonal bracing that would transfer load across the hull and incorporating iron components. When he presented his ideas to the Royal Society, he likened his solution to adding the diagonal strut to a five-bar gate. Soon he was able to test the system fully, building his trussed frame into HMS Warspite (74). It cured hogging at a stroke, permitting the development of much larger warships, starting with HMS Howe, the first of a new class of 120-gun first rates, launched in March 1815.
In 1813 Seppings was promoted to Surveyor of the Navy, a position he held until his retirement 20 years later. This placed him in charge of all Royal Navy warship design, and under him change came quickly. Having solved the hogging problem, he turned his attention to other improvements. Eighteenth-century warships were most vulnerable to an enemy firing down their length through the stern or bow—“raking” them. Seppings dealt with these weaknesses by introducing strong round bows and sterns. The stern proved unpopular with senior officers, because it robbed them of the spacious cabins they had enjoyed in traditionally designed ships.
Seppings’ career came at the very end of an era. He had been schooled in the most traditional of environments and could easily have opposed change, as most shipwrights did. His importance rests on his rejection of the easy path and his restless desire to find improvements. He was not the last of the Age of Sail’s ship designers but the first of the innovators who would transform warships forever. He was made a Fellow of the Royal Society and, in 1819, knighted. He died in 1840, having risen from rural obscurity to become the most prominent ship designer of his generation.
