By 1792, six Royal Navy dockyards employed about 1500 workers each. The dockyards had a wider variety of technical specialties than was found in any other manufacturing enterprise. The dockyards “were some of the largest manufactories in Europe and dwarfed almost all private industries.” (Morriss) The dockyards built new ships, but maintaining ships was just as important. The Royal Navy’s dockyards constituted one of the largest industrial maintenance organizations in the world…and their only peer organizations in terms of the scale of maintenance management were the dockyards of other superpower navies.
Centralization and Bureaucracy Improved Maintenance
Historian Roger Morriss studied how the Royal Navy organized and managed dockyards in the 1700s. He noted that the period was characterized by increasingly centralized administrative control. Centralization occurred within each dockyard and also led to increased oversight of the dockyards by the national naval establishment. The strengthening bureaucracy would improve its ability to manage maintenance costs and oversee the purchase and stocking of repair material.
An example of the increased centralized management occurred in 1744, when an assistant to the Navy Board, the young Earl of Sandwich, requested 40 years of data and analysis regarding dockyard employment and overtime levels, lists of rebuilt ships, and the details of mechanical ventilators for ships. (NAM Rodger, p. 28)
By 1749, the Earl of Sandwich had been promoted to be the First Lord of the Admiralty. Sandwich had the Navy Board conduct site visits to dockyards as a group for the first time – a national-scale gemba walk. Like other management visits, the Board was motivated by poor adherence to cost and schedule:
“…taking into their consideration the number of Men Borne in the several Dock and Ropeyards, the great Expence Attending the same, And that the Works are not carried on with the Expedition that might be expected from them, which must arise from the remisness of the Officers, or Insufficiency of the Workmen, or both…” (PRO/ADM 3/61 quoted by Rodger, p. 64)
The Board found idle workers, bad oversight, timber and naval stores in disarray, reserve ships in bad condition, and facilities decayed. These observations would motivate the Earl of Sandwich to improve these issues when he returned to the office of First Lord in 1763 and again in 1771.
Another example of the increasing oversight were Progress Books, which contained weekly reports of movements in and out of dock, labor, and details of damage and decay. Each dockyard compiled reports into the Progress Books and submitted them to the Navy Board. (Knight, p. 26)
The Navy carefully reviewed the project cost and schedule performance contained in the Progress Books. The project data allowed the Navy to predict maintenance schedules for individual ships and for the fleet in aggregate. In 1758, the Navy used this information to forecast the size of the fleet available for missions two years in advance. (Morriss Foundations, p 151, footnote 94)
Alternating Overhauls
In a ship’s lifecycle, complex and invasive repair periods alternated with shorter preventive maintenance periods called refits (Morriss Foundations p. 158). This was similar to a complex maintenance strategy familiar to automobile owners, where tasks are prescribed at multiples of an interval. For example, spark plug replacement might be recommended every other repetition of 15,000 miles. In modern computerized maintenance management systems, this can be called a “job plan sequence” or a “strategy plan.” Modern naval ship life cycle plans typically contain alternating cycles of short and long repair periods.
In the 1740s, a refit took about 2 months for a frigate and 3-4 months for larger ships of the line. A 74-gun ship underwent a “small” repair in about 10 weeks. A “middling” repair took about 10 months. A “large” or “great” repair lasted about 16 months, depending on the extent of rebuilding. Once copper sheathing was introduced, it was replaced every 4-5 years.
The scope of repairs for the longer repairs was determined by inspections performed by dockyard surveyors…essentially an element of condition-based maintenance. Morriss gave the example of the HMS Defence between 1780 and 1805 which visited dockyards 11 times and received larger repairs every 10 years. (Morriss Foundations p. 158)
In his thesis research about the management of dockyards, R. J. B. Knight compared the contemporaneous letters about the perception of the length of refits with actual yard performance. Over the course of 40 years, 74-gun frigates on average spent 5 weeks preparing for docking, three weeks in refit, and 6 weeks getting ready for sea. (Knight p. 348).
The length of refits came under pressure during war. The navy put several policies into place to shorten refits, accelerate the rate of turnover, and keep more ships at sea. One method was to prioritize the easy work and refit the ships in the best condition. Emphasis was placed on having correct Progress Reports. (Knight p. 363) Work was to be evenly distributed between the dockyards. Standard work was attempted, at least in principle.
The main causes of delays were unplanned increases in scope, bad preparation by the crew, who were supposed to clear the stores beforehand, and work changes demanded by the ship’s officers that were unscheduled and unbudgeted. (Knight p. 352-355) The independence of ship commanders and the informal influence of their political sponsors sometimes resulted in favoritism overriding technical decisions. Written and unwritten technical rules about refit, changing ballast, the sail plan, or other modifications were sometimes ignored.
Groping Toward Professionalism
Kenny had observed that in the 17th century the navy was “groping toward professionalism” as it slowly abandoned the view of official government posts as medieval fiefs, where the incumbent owned the office and profited from it. Knight found a situation in the 18th century that was better and still improving.
“It was at this point that the status and social ambiguities within the service most weakened administrative efficiency. This was a problem which beset the service through the
century, and efficiency was not to be radically improved until the independence of the commanders had been curbed, and civil administration made more powerful.” (Knight p. 361)
This continued professionalization of the administrative bureaucracy led to improvements in most areas of the navy. In 1747, navy officer ranks were made equivalent to army ranks, the navy defined what an officer’s uniform looked like, and naval officers were finally paid annually. A method was introduced to promote captains based on merit, and a revision to the general regulations was started. (Rodger, p. 33-34) This professionalization would also benefit the management of preventive maintenance. The growing bureaucracy would improve the efficiency and the military value of the maintenance and repair organization.
3-Year Maintenance Cycles
Triennial trimming was an event where the ship was docked for thorough cleaning and repair of the hull below the waterline. Graving was a complete cleaning of the hull. Ships were pulled up on a beach, set down in a dry dock, or turned on their side while still afloat. During the cleaning, small repairs were made. In his 1690 memoirs, Pepys criticized the management of hull maintenance during his 4-year absence from fleet maintenance management . Pepys emphasized that a third of the fleet needed graving every year. At this rate, each ship was cleaned, inspected, and repaired every 3 years. (Select Naval Documents, p. 82) A root administrative requirement to conduct triennial trimming for preventive maintenance in the 17th and 18th centuries has not been identified, but the practice was common and evident in correspondence.
On March 1st, 1786, the British Parliamentary History recorded debates about copper sheathing that included a captain referring to customary annual and triennial trimming (Albion p. 212) The speaker, Captain John MacBride, spoke as an authority on copper sheathing because of his experience commanding a 64-gun copper-bottomed ship during the moonlight Battle off Cape St. Vincent in 1780. In addition, he was the MP from Plymouth at the time, providing both testimony and voting on national policies concerning hull maintenance and the adoption of copper sheathing.
Lavery found that HMS Victory had triennial trimming in his book Nelson’s Victory: 250 Years of War and Peace. Hill and Ranft discuss triennial trimming in The Oxford Illustrated History of the Royal Navy.
The history of the HMS Belliqueux by the website Threedecks.org shows that the ship was trimmed every three years during the period from 1756 to 1772…even though the Belliqueux was a 3rd rate ship of the line and a prize captured from the French.
Morriss and Knight both observed that triennial trimming was routine but informally managed until the American Revolution, when the navy was under great pressure to have more ships at sea instead of undergoing maintenance. (Knight p 24) Toward the end of the American Revolution, most of the fleet had been fitted with copper bottoms which eliminated the need for most hull cleanings. Replacement of copper sheathing was much less frequent than trimming had been. As a result, some frigates were kept at sea until other problems like structural deterioration or leakage required emergency repairs. This would have a negative influence on the adoption of copper hull sheathing. (Morriss Foundations p 154 and Knight thesis p 342)
From the late 1600s to the late 1700s, the Royal Navy had a strong habit of periodic hull maintenance, but with no centralized administrative program. Over this century, the naval establishment improved its managerial capacity. During the American revolution and the installation of copper sheathing, the navy had to become more involved in monitoring and managing docking cycles.
Triennial Trimming – sources and references
Morriss, Roger, The Foundations of British Maritime Ascendancy: Resources, Logistics and the State, 1755–1815, Cambridge University Press, 2011
Morriss, Roger, Science, Utility and British Naval Technology, 1793–1815: Samuel Bentham and the Royal Dockyards, Routledge, 2020
Rodger, N. A. M., The Insatiable Earl. A Life of John Montagu, 4th Earl of Sandwich London: Harper Collins, 1993
Knight, R. J. B. “The Royal Dockyards in England at the time of the American War of Independence”, University of London Ph. D. thesis, 1972
Albion, Robert Greenhalgh, 1896-1983. Forests And Sea Power. Cambridge: Harvard university press, 1926. https://hdl.handle.net/2027/mdp.39015058425045
Hodges, Harold Winter, and Edward Arthur Hughes. Select Naval Documents. Cambridge [Eng.]: University Press, 1922. https://hdl.handle.net/2027/coo1.ark:/13960/t3902pz3f
Kenny, Robert W. Elizabeth’s Admiral, The Johns Hopkins Press, 1970
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