How the Diesel Engine Became King of the Seas

The diesel engine, a mighty powerhouse for big machines on land and crucially at sea. Today the world's biggest ships are powered by mammoth diesels with pistons the size of small trees that can weigh in excess of a half ton alone. But diesels had once been a kind of underdog because they were up against the then undisputed king of ship engine technology, the steam engine. For the better part of a century the steam engine had powered the world's largest and fastest ships. By the 1920s and 30s it had essentially been perfected but then along came a brilliant inventor and a handful of innovative designers keen to change the game. The result was the rise of an engine that still works to drive the biggest machines ever built by humanity. Ladies and gentlemen I'm your friend Mike Brady from Oceanliner Designs and this is the story of how the diesel engine became the engine for ships at sea. Of course as far as diesel engines are concerned there was once a before time. The rise of the steam engine had been a revolutionary explosive force. By the 18th century steam engines had the ability to properly harness the expansive force created by steam and already there were some very early theories that steam power could be used on ships. It wouldn't be long before those theories would formalize into concrete plans. In 1763 the English inventor Jonathan Hulls was granted the very first steamship patent. In his plan he'd use a steam powered engine to drive the paddle wheel on the back of a tugboat and use it to navigate in and out of the harbour. But unfortunately for Hulls it appears the idea didn't really get off of paper and into a practical application or trial. But importantly the idea was now out there and it wasn't long before others would try the same thing. By the early 1800s Hull's vision had become a reality and steam powered engines were gutsy enough to drive tugs that could haul sailing ships in and out of port. This was a huge advancement for marine technology. To vastly cut down the amount of time ships had to spend sitting in their moorings waiting for the weather that would get them out to sea. Eventually big ships got their own steam engines too and it cannot be understated just how important steam was to the advancement in shipping for passenger and cargo service alike. There was no going back. See before steam ships had to rely on the weather or the manual rowing of oars to get around. Now this made for very unpredictable voyage times. The ship was only as fast as the wind could take it and the wind is extremely erratic as a source of propulsion you just can't control when it comes and goes. Ships powered by steam no longer had to wait on the weather so scheduling voyages became much easier and more predictable. Ships for really the first time ever could reliably operate year-round on a reliable schedule. Steam ships were also just more powerful. They were better equipped to handle rough weather when they're out at sea. Voyages were much faster. Big ships could complete their journeys in a matter of weeks and then days after previously being subjected to life at sea for months on end. That and of course steam engines allowed ships to better navigate bodies of water where the wind was much less prevalent than the ocean, like on rivers. So steam-powered ships dominated the sea and some of the most famous ships of all time were powered by steam like the Lusitania and the Titanic. It reached its heyday with the development of the Parsons turbine, a brilliant bit of technology that's actually still in use today. It was capable of outputting enormous amounts of power and it drove the world's fastest ships like the Queen Mary and the SS United States. But just as it Steam ships were hitting their stride and being perfected, along came the diesel engine with all of its many advantages and shipping would once again undergo a huge transformation. Steam ships were getting faster seemingly with every launch. Ocean liners were frequently surpassing each other. Turn the blue ribbon across the Atlantic. There was no apparent need for new technology on the surface. People were getting to where they needed to be on ships faster than ever but innovation doesn't happen by just sitting around. Rudolph Diesel was a French-born Bavarian engineer who'd become obsessed with the idea of creating a combustion engine that capitalized on achieving what was known as an ideal thermodynamic cycle. It was all a drive to get the most fuel efficiency out of an engine. In 1893, Diesel published a paper called, prophetically, Theory and Construction of a Rational Heat Motor with the Purpose of Replacing the Steam Engine and the Internal Combustion Engines Known Today. Catchy. Diesel was dreaming of an engine that transformed heat energy with insanely high thermal efficiency. It sounds complicated but the truth is that this early attempt at theoretical writing was flawed and received some bad feedback from engineers at the time. So Diesel went back to the drawing board not deterred and instead he filed a patent for a kind of motor that did away with spark plugs. See, petrol engines need spark plugs. They create the artificial source or spark that ignites the oxygen and fuel mixture creating the internal combustion that the engine needs to drive its pistons. But Diesel's engine instead used a system that would take a small portion of fuel and compress it so much that it creates heat high enough to ignite the mixture and repeat the process. The end result was a motor that created huge power at relatively low engine revolutions. It was extremely efficient when compared with petrol engines of the time and especially steam engines. For example the gasoline used in petrol engines burnt up very quickly but the diesel fuel used in this new kind of motor burned slower and just gave more grunt. By 1897 Diesel had built his first proper motor. A four stroke 25 horsepower machine that was much cheaper to run than a steam engine or a petrol engine of the same size. Very quickly Diesel became a very wealthy man and his name was synonymous with his new engine. In 1906 the shipbuilding firm William Doxford and Sons began planning to introduce diesel internal combustion engines on their ships. With such a jump at the idea it's no surprise that Doxford became one of the leading shipyards at building and designing what was then called a motor ship. Their plans were paused by the outbreak of World War I but at the conclusion of the war their work resumed on a diesel type four cylinder engine. They were very pleased with the results of tests and trials and determined that the power plant was suitable for ocean going vessels. There were a few huge benefits but the key ones were that first a diesel engine burned liquid fuel. Traditionally steam ships had needed big coal bunkers and hundreds of men to operate all the boilers. Diesel ships did away with all that you just need a handful of engineers by comparison. But the other main point one of the things that made diesel engines so attractive as an alternative propulsion system was that insane torque. That huge amount of power generated at low revolutions. Coupled with the fact that diesel engines despite their impressive size were significantly smaller than steam engine installations from the time and designers had a machine that was ideally suited for use in their ships. But it would take some teething to get right. Another early adopter of the marine diesel engine was Burmeister and Wayne a Danish firm which negotiated exclusive Danish manufacturing rights with diesel all the way back in 1898. Then in 1912 the world's first large diesel powered ship went to sea the MS Silandia powered by Burmeister and Wayne engines. So enthusiastic were our designers to show off this new technology that the typically tall funnel so linked with ships of the time was done away with entirely. It was a novelty that drew attention everywhere the ship went. In 1921 Doxford completed work on their first diesel powered ship too the Swedish merchant vessel Ingeren. The Doxford diesel was an immense success and it was used on many future ships. Naturally the design was perfected over time but it created a new breed of vessel the motor ship and suddenly after the first world war they began to pop up all over the place. But it didn't always go smoothly. In 1926 Harland and Wolff had just completed the new motor vessel Asturias an elegant luxury liner for the royal mail line. They'd put their own four-stroke diesel engines in but they underperformed alarmingly and the ship was only capable of a paltry 16 and a half knots at a time when others competitors on the same service were managing 20 and more. Eventually the ship and her sister were re-engined with steam turbines that did give them better speeds but it would be a very rare instance indeed of a ship being re-engined for steam and not the other way around. So why the rush to develop diesel engines for ships so quickly? Well the diesel engine even in its early unrefined stage gave massive efficiency bonuses. In fact ship owners reported that the new engine was around 40 percent more efficient on fuel than steam. MS Vulcanus the first diesel powered ship from 1910 burned around two tons of oil where competing steam ships needed to burn 11 tons of coal. But there were other economic advantages as well. Famously steam engines are very slow to fire up. A boiler could take an hour or more to produce steam from a cold start even if another boiler on the ship was available. It would take even longer if the entire power plant was shut down. Operators of steam ships knew this fact so often they would leave more boilers running than were actually needed to avoid needing a full restart when it was time to get moving again. The boilers would be sitting idle but burning through coal. Diesel engines on the other hand could be powered on and reach full capacity almost immediately. They could then be shut down just as quickly. Plus the stowage space for fuel on a diesel ship is far less than that of steam ships that needed coal. More spaces on board could be devoted to cargo and passengers and less on fuel. Diesel ships ran cleaner as well. They're more environmentally friendly than coal burning ships not like that really mattered back in the 1910s and 1920s but they were also generally cleaner for those on board. Coal burning left behind smoke ash and soot that could often rain from the sky so shipbuilders had to build tall funnels to direct those emissions into the air well above the passengers heads. If the funnels weren't tall enough passengers could get covered in soot. Now this is not as much of a concern for diesel ships although designers still made it a good practice to make sure the funnels were tall enough to vent those noxious diesel fumes well over their passengers. Now diesels proved a worthy upgrade for warships as well. In the second world war some of Germany's most impressive warships were powered by diesel engines but the impact was especially felt in submarines. Submarines were never really a good fit for steam engines to put it lightly as we've explored with the disastrous British K-class submarines. Steam engines need a lot of holes cut in to allow for all that smoke and fumes and holes in submarines generally aren't really a good idea. Now as far as diesels are concerned there were some early downsides. Diesel engines were less powerful per unit weight than steam engines of the time and early on they were not always really the most reliable but still development and testing plowed on ahead. 1924 saw the launch of the first large diesel passenger ship the Aurangi built by the Fairfield Shipbuilding and Engineering Firm of Glasgow for the Union Steamship Company out of New Zealand. She was a shiny example of what diesel ships could be for passenger travel even though she was actually not originally designed to be a motor ship. She was about 580 feet or 176 meters long displaced around seven and a half thousand gross registered tons. She was equipped with four six-cylinder diesel engines which gave her a service speed averaging a little over 16 knots. Her maiden voyage was in January of 1925 sailing to Vancouver from Southampton via the Panama Canal. Now along the route it was recorded that Aurangi was gaining around 12 hours on the schedule set by her steam powered fleet mates. Aurangi would go on to have a successful career of nearly 30 years serving passengers all around the world as well as being a troop ship in the second world war. A fun little quirk of the Aurangi's design is that even though she didn't really need them their designers gave her two very tall funnels probably because they thought passengers were just used to seeing tall funnels on ships but as the 1920s and 30s wore on motor ships funnels shrank in size to effectively show off that cool new technology. Now steam was still the speed king. It was almost impossible for diesels even though they are very efficient and powerful to compete with the raw power of a liner's superheated steam turbine system. The SS United States turbines for example developed an eye-watering 247,000 shaft horsepower but for ships that didn't need to break the speed record diesel engines became the done thing. The fuel savings and all the other benefits were just too good to pass up. Eventually most new ships were being designed and built with internal combustion engines in mind and the symbolic passing of the torch from steam to diesel happened in 1987 when one of the most famous ocean liners of all time actually switched her engines over. Queen Elizabeth II or the Kiwi II as she's affectionately known is one of the most famous ships of all time and until the arrival of the Queen Mary II she was the only ocean liner still actually in service. Her construction was completed in 1968 and her maiden voyage came the following year. She was originally built with traditional steam turbines but almost two decades into her career her owners the Cunard line wanted to explore the idea of a power upgrade. Cunard wanted the ship to sail with improved fuel economy to reduce the maintenance costs and really extend her service life. The company reached out to engine builders around the world to hear pitches on what could be done for the liner. They were open basically to considering all options including just leaving the existing propulsion system in place with some modifications but ultimately Cunard went with a diesel conversion. Of all the proposals that retrofit would require the greatest initial cost and a huge amount of work but projections showed it would result in the greatest operating cost savings between the new diesel engines and the other optimizations to the ship while she was in dry dock. With the plan in place Kiwi II underwent her steam to diesel conversion from 1986 to 1987 at the Lloyd Werft shipyard in Bremerhaven Germany. This 162 million dollar refit would be one of the biggest conversion jobs amongst merchant ships at the time. Her tall thin funnel and its casings had to be cut off and the monumental steam plant broken up and winched out. Then in went the diesels and like surgeons sewing up a patient's chest after surgery a hefty new funnel was welded into place on top of it all. The conversion was ultimately a major investment in both time and money for Cunard but they must have been ecstatic with the results. The new and improved Kiwi II was mechanically a nearly brand new ship. With a new maximum service speed of 33 knots she was now the fastest and most powerful merchant ship in the world but not only was she fast she was incredibly efficient. Initial indications showed fuel savings of around 30% annually meant that Kiwi II would be saving at least six and a half million dollars in fuel per year. With a new lease on life the Kiwi II would sail for 21 more years an incredibly impressive feat when you remember highly successful ships from the past like Olympic only serve for 25 or so years in total. In the end she'd become the longest serving Cunard of all time and traveled further than any other ship had before both feats thanks to her diesel refit. Interestingly Kiwi II's conversion isn't actually a one-off other ships over the years have received similar refits. The Indian Navy frigate INS BS was built with steam turbines for their raw power output when the ship was completed as late as the early 2000s but now she's set to be upgraded from steam turbines to diesel. The work was actually started in 2024 and it's scheduled to be completed next year in 2026. It's estimated that the conversion will extend the career of the INS BS by up to 10 years and once the work's completed the same conversion will occur on the remaining two ships in the class. It seems that just as soon as a new technology arrives on the market its replacement is almost always already waiting in the wings. History has shown this fact to be just as true with shipbuilding as it is with anything else. The 19th and the 20th centuries were a hotbed for rapid technological design and development. In just a few stunningly short decades ships of the world went from sail to steam and then to diesel. As prominent as diesel engines are in ships today they too at some point will probably be replaced by something else entirely. The irony of it all is that the next logical leap forward in ship propulsion nuclear power is really just steam power with a never-ending source of heat. So maybe one day if nuclear-powered ships really become a thing then steam will win out over diesels at last. But the fact is now that ships of all shapes and sizes are powered by diesel engines. Now here's a curious footnote. The man who gave the engines his name, Rudolf Diesel, mysteriously disappeared off the back of an ocean liner in 1913. Some say it may be because of the fact he refused to sell manufacturing rights for diesel engines to the German navy who were desperately trying to beef up their fleets at the time. That he might have been got rid of by the powers that be. Such was the sheer impact of his invention. But tragically that brilliant innovator would never get to see his invention reach anywhere near its full potential. Today big ships diesel engines are monstrous things. The Wärtsilä-Sülze-RT-196C engine for example is a 14-cylinder, 44-foot, that's 13 and a half meter tall, 2300 ton behemoth. It outputs over 107,000 horsepower alone. If only we could go back in time and show Rudolf Diesel what his invention would eventually become. Ladies and gentlemen it's your friend Mike Brady from Ocean Liner Designs. Thank you so much for watching this video. If you enjoyed it please leave a comment below. Don't forget to subscribe to the channel because we get new videos out weekly. 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