Oil Tanker Tour

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It’s getting increasingly difficult for the general public to see the details behind large commercial ships and even harder to tour chemical and oil tankers. Partly the crews are busy at work and partly there are safety and security concerns, but the net result is limited ability to see the details behind how these advanced ships work and the design tradeoffs they chose to make, and to learn more about how they actually work. So when we had a chance to tour two modern 491ft (150m) oil tankers and one 203ft (62m) commercial fishing trawler, we jumped at the opportunity. And what a tour it was—we had nearly unlimited access to all parts of each ship.

In the 28th edition of our Technology Series, we tour the 491′ (149m) oil tankers Ramanda and Fure Ven, and the 203 ft (62m) pelagic trawler Ceton. The ships were all moored at Donso near Gothenburg, Sweden and were made available to the public the day before the Donso Shipping Meet.


Oil Tanker Ramanda

We started the day with the Ramanda, a 491ft (149m) product and chemical tanker displacing 18,200 deadweight tons.  This vessel was just completed in July of 2018 for Alvtank and has been in use for more than a year, but still feels brand new both in design and in operation.

The first thing you’ll notice when looking at these new tankers is, where a normal oil tankers has a flat deck with pipes and plumbing, very large LNG tanks dominate the decks of these ship. Ramanda‘s LNG tanks have a combined capacity of 600 cubic meters (158,503 US gallons) and this is the primary fuel they operate upon.

The Ramanda is a single engine vessel. Using a single engine is slightly more fuel-efficient and correspondingly has less emissions than a multi-engine approach. The Finnish company Wartsila provided the main engine for Ramanda,  a Wartsila 9L34DF. The engine puts out 4,500 KW (6,118 hp), on the low side of what might have historically been used on a tanker of this size needing to achieve Ice Class 1A.

The Ramanda is able to use a less powerful propulsion engine and still achieve Ice Class 1A by using a propeller nozzle. Propeller nozzles are very common on tug boats and they really improve slow boat speed, important in both tug boats and ships taking on thicker ice. At higher boat speeds, nozzles are actually slightly less efficient, but one of the most important design goals for the Ramanda is fuel-efficiency and the designed sailing speed is only 12 kts. Higher speed operation isn’t their goal, so the nozzle works fine and the estimated additional 25% more thrust at low speed has the advantage of allowing the use of a smaller and more fuel efficient engine.

Oil tankers have historically been heavy oil burners or, in cases where heavy oil can’t be used, they ran diesel. Why accept the additional expense of being able to run on LNG?  The decision was driven by 3 main reasons: 1) tightening regulations on sulfur emissions (max 1.5% in the Baltic, max 0.1% in EU ports, and max 0.1% in the North Sea), 2) a societal and political environment where climate change, sustainability, and public health issues are high on the agenda of Nordic countries, and 3) customer awareness causing pressure on refinery owners to reduce the emissions of their logistics channels and on oil terminals to reduce emissions, smell, and noise.

The Wartsila 9L34DF can run on LNG, diesel, or even heavy oil. Although the Ramanda is primarily LNG-powered, it has tanks on board for 600 cubic meters (158,503 gal) of LNG, 170 cubic meters (44,909 gal) of diesel, and 540 cubic meters (142,652 gal) of heavy oil. Diesel and heavy oil burning engines are referred to as CI or Compression Ignition engines, where the fuel is injected into the engine near the highest point of compression and the heat of compression ignites the fuel. Hence the term “compression ignition”. Gasoline and LNG burning engines are referred to SI or Spark Ignition engines. In this design the fuel and air mixture is brought into the combustion chamber together during the input stroke, and near the end of the compression stroke a spark plug ignites the charge.

What we found super-interesting is how Wartsila combined these two concepts in an engine able to run in either mode. When operating in CI mode the engine injects diesel or heavy oil exactly as any diesel would normally. In LNG mode, LNG is injected into the air charge before it enters the cylinder. Once the air/fuel charge is close to maximum compression, the charge is ignited by injecting a small amount of diesel. Wartsila is effectively using a small diesel injection as a very large version of the spark plug that is used in smaller spark-ignited engines.

This design approach allows a great deal of fuel flexibility but it also supports some very important safety characteristics. Since LNG can be explosive if it leaks in the engine room, the LNG system is shut down immediately if any leak is detected. But it’s dangerous to have the main propulsion shut down on an oil tanker. If the ship is operating in close quarters and the engine does an emergency shutdown, a collision and an oil spill could result. So the Wartsila engine will switch between LNG and diesel operation without shutting down the engine. In fact, the chief engineer explained that this change can happen without the bridge crew even knowing it. The ship can switch from LNG to diesel without the engine missing a beat or even momentarily losing power.

In the first picture from the Ramanda engine room, the main engine is on the left with the transmission on the right and a portion of the shaft generator just visible on the right hand side of the transmission. The picture below that shows transmission temperature readings indicating transmission health, with the warning to disable auto-shutdown after sea trial. Auto-shutdown is used to protect the equipment prior to the boat going into operational use. Once in use, over-temperature or other alarms are warnings to the crew and captain, but you don’t want the system removing power from an 18,200 ton oil tanker possibly operating in close quarters. In the picture on the right, taken from the other side of the transmission, the propellor shaft extends to the left of the transmission into a partially-visible shaft generator. Why run a shaft generator rather than a dedicated generator?

Modern ships have large power requirements both for hotel loads, but also for thrusters that alone on the Ramanda can consume 850kw. As a consequence of heavy electrical requirements, one or more generators typically are running continuously. An efficient approach is to run a large shaft generator off the transmission as seen here. This means the main engine not only drives the ship but also supplies up to 3,000 KW of electrical power. The main engine alone can run the thrusters, the steering gear, the emergency anchoring system, all lighting, and the ship navigational systems. This is more efficient than running one or more generators in that these loads just more fully utilize the main engine, and using a single engine when underway requires less frequent service, oil changes, etc.

The problem with running a shaft generator is that a single fixed engine speed must be used in order to produce the fixed frequency of 50Hz (or 60Hz) electricity required on board. With a variable-pitch propeller, a single engine speed can be maintained at different boat speeds, but that is both a constraint on ship operation and can reduce engine efficiency. On the Ramanda, the main engine speed is set to match the needs of overall engine load to maximize efficiency and fuel economy. Rather than run the engine to generate the appropriate electrical frequency, the engine is operated at the speed appropriate to the load, and the shaft generator produces variable frequency power, sometimes higher than desired and sometimes lower. Then to produce the nice clean 50 Hz (or 60Hz) power needed on the vessel, this variable frequency power is fed through a frequency converter (shown in above diagram).

The downside of this super-efficient single engine approach to propulsion and power production is that any failure of that engine or the shaft generator could end up being a very serious problem. Let’s first look at what happens when the shaft generator fails. Since this is the entire source of power for all hotel loads, steering, emergency anchoring, and navigation equipment, it’s not acceptable to have a single source of power. This gear is protected in very much the same way that modern data centers are protected. An uninterruptable power supply (UPS) will pick up the load without noticeable gap on power failure. On the Ramanda, the UPS will take the load for up to 20 minutes. Of course 20 minutes is not sufficiently long, so backing up the UPS are two dedicated generators. Either or both can be used to backup the shaft generator. The combination of UPS and backup generators means the critical electrical loads should never see a power loss.

Above we talked about how the ship will operate without problem through a shaft generator problem but what can be done if there is a main engine fault? One of the primary reasons why many even small oil tankers often have dual engines is redundancy. We never want an oil tanker operating caught without propulsion. In close quarters it could lead to collision and fuel spills and the Ramanda is designed to operate even in narrow waterways where engine redundancy is required. Twin engines is an easy solution but this is slightly less efficient than running a single engine. The Wartsila approach to this problem is an elegant one.

In normal operation, a single engine drives both the shaft generator and the main propellor. On engine failure, the shaft generator can be operated essentially in reverse as an electrical motor. When the shaft generator is being used as a motor, it’s often referred to as a “pony” or “get me home” engine. If the main engine fails, the propeller and the shaft generator stop and neither propulsion nor power is available. The UPS system will maintain the electrical load during main engine failure. The secondary generators are then started, the inoperative main engine is clutched out and the shaft generator is then fed power and will run as a motor rather than as a generator. The 3 megawatt generator now becomes an electric motor, able to drive the ship. This is how Wartsila gets the efficiency of a single engine with the redundancy of dual engines: the on-board generators cooperate to form a redundant power system.

Pictured above is the 1.6MW Wartsila generator on the starboard side of the engine room. Another 800 KW Wartsila generator is on the port side.  They can both be operated synchronized together for up to 2.4 MW of electrical power. This is enough power to drive all boat systems and even provide propulsion through the pony motor in the case of an electrical failure. Having two generators allows the dropping back to using just a single generator when less than 2.4 MW of power is needed. And, when in port and the main engine is off, the 800KW unit can be used to support hotel loads or is shut-off entirely if sufficient shore power is available.

The pictures above are from the Ramanda control room where the forward wall is electrical controls and the back wall is a window into the engine room. In the middle is a console with video displays showing all engine, transmission, and other mechanical systems status. Because modern ships run relatively small crews, video displays showing all key equipment allow everything to be monitored from the engine control room. Running the engine and mechanical spaces nearly unoccupied helps reduce manning levels and increases personel safety. If an LNG leak is detected, the engine will immediately switch from LNG to diesel operation without missing a beat and the engine room will be flooded with inert gas to reduce the explosion risk.

These pictures are of the purifier room housing the lube oil centrifuges as well as the fuel oil purifying equipment that includes centrifuges, heaters, coolers, and filtration. The second picture is of a large heat exchanger used to heat or cool the fuel oil.

The Ramanda is well-equipped with tools, and even a good-quality lathe. Although these ships are capable of transoceanic runs, most of their work will be done in the Baltic region and most heavy mechanical work will be done by specialized service personal. But the crew is trained and equipped with sufficient tools and machinery to recover from most problems underway.

The first picture above is of the helmsman’s console at the bridge, looking out over two comfortable seating positions that have access to all instrumentation and navigation related controls on the boat. The second picture is of the twin seating positions in front of the navigation equipment.

In the pictures above, the first shows the central console between the two navigation equipment seats. Both seats have easy access to engine, thruster, chart plotter, RADAR display, Radio, Intercomm, and other navigational equipment. The RADAR is a beautiful FURUNO RCU-014. The second picture is the view forward from the navigation console seating position.

The first picture above is the bridge wing control console. Beyond at the bridge wing you can see the members of the crew checking on boat positioning. It’s blowing 20 to 30 kts today and the Ramanda isn’t actually tied to the dock—it is held in place by a web of fixed moorings that are dragging. A small supply vessel is pushing against the aft quarter of the Ramanda to help fight the effect of the winds and hold it in place without further moorage dragging. One crewmember is on the radio requesting line tension changes and speaking to the supply vessel.

The second picture shows the control panel at the starboard wing station. A navigational chart display is here, along with easy access to the main engine, transmission, and thruster controls as well as radios and intercom systems along with warning, alarms, and indicator displays.

On the port side of the bridge is the product tank control area. From here there is a good view forward but, more importantly, there is a good view out over all the product tanks and plumbing. Clear video displays show the current plumbing configuration and tank levels plus boat trim and list, current draft, and wind speed and direction. Also visible from this location are the product temperature, the power currently available for pumping operations, and the power currently being used. Warning lights and alarms can be triggered on tanks full and will be triggered on tanks over full.

Pictured above are the forward lines and winches on the Ramanda. Each line is 754ft (230m) with a breaking load of 50 tons. Two of the forward line winches are combined anchor rode/line winches that also handle the 12,367 lb (5610kg) anchors. In addition to the two anchors installed and ready to go, they also carry a spare anchor of the same size on the deck mid ship. The last picture shows a link from the anchor chain with Jennifer’s hand for relative size.


Pelagic Trawler Ceton

The next ship we toured was the Gifico-owned trawler Ceton. The Ceton is a 203 ft (62m) pelagic trawler primarily fishing mackerel and herring and some other lesser-known species available in the area. This ship is a modern build, not yet two years old, and is well-equipped with four net drums.

The Ceton is powered by a medium speed Caterpillar MaK 8M32C producing 2,999 kW (4,021 hp) at 600 RPM. Like the Ramanda, the Ceton also uses a shaft generator to allow them to run the entire boat on a single engine when at sea.

The boat can consume a lot of power for its size since, on top of the standard hotel and a navigation loads, all fish and fire pumps, net drums, and winchers are all electrically powered. The Ceton is equipped with 2 electric thrusters, one of 1,292 HP and the other of 1,156 HP.

To provide backup power in case the main engine isn’t running or the shaft generator is inoperative, they also have two generators, a Caterpillar C32 producing 940 kW and a Caterpillar C18 producing 500 kW.

In the second picture above Dirona is visible slightly left of center on the chart displayed at the bridge of the Ceton (click image for larger view). Some of the bridge crew had seen us arrive in Dirona earlier in the day and we had a lot of fun talking through similarities and difference between our boat and the Ceton. As different as the boats are, there is still a lot in common. Both boats use a single engine for all house power when underway. We share some navigation equipment choices, including both using TimeZero navigation software. And both have a lot of automation to allow comfortable operation with a small crew. And Dirona has four monitors in the pilot house displaying navigation and automation information, but we use 19-inch displays rather than the massive 56-inch units on the Ceton.

The Ceton is designed to be highly automated, requiring minimal manual effort. We were amazed to learn that the entire operation can run on a crew of only six. We also were impressed with the cleanliness of the vessel, in fact of all the vessels we toured. But the Ceton really stood out—the entire ship, including the fish holds and the engine room, was virtually odor-free and the pilot house is kept so clean that street shoes aren’t allowed inside. Rules like these are typically found on nicer yachts, not large commercial fishing boats.


Oil Tanker Fure Ven

The product and chemical tanker Fure Ven, owned by Furetank Group, is a sister ship of the Ramanda that we’d toured earlier in the day. The Furetank fleet are regional product and chemical tankers carrying light oils (diesel, jet fuel, kerosene, biodiesel, etc.) operating in the Baltic, North Sea, and English Channel as far south as Spain. The second picture shows typical trips made by Furtank Group vessels. The newest Furtank Group ships, and the Ramanda, were built at the AVIC Weihai Shipyard in China and are 491′ (149m) long and displace 18,200 deadweight tons. Like all the new Furetank builds, this is a multi-fuel boat able to run on LNG, diesel, or even heavy oil.

The difference is the Ramanda is a bit more than a year old whereas the Fure Ven is brand new. In fact, it’s so new that later in the day, we got a chance to attend the christening celebration where the Fure Ven was officially named and put to work. The celebration was fun to watch, with presenters including the CEO of the Furetank Group, the owner of Fure Ven, and also attended by the General Manager of the AVIC Weihai Shipyard where both the Ramanda and the Fure Ven were built.

The first thing that jumps after having spent time on the Fure Ven, which is just entering service, and the Ramanda, which has been actively operating for more than a year, is there is almost no difference. A year of wear and tear is effectively invisible. There are no leaks from any of the Ramanda engines, there is no dirt on anything, there is no noticeable difference anywhere. 

We’re sure there are some meaningful differences between the Fure Ven and the Ramanda, but other than the Fure Ven having a blue hull rather than red and the engine being painted a light blue rather than dark, we didn’t see many differences. All the design features on the Ramanda are carried forward on the Fure Ven.


Single Engine for Power Generation

It’s interesting that all three of these boats are single-engine boats, just like Dirona. And for much the same reason that Dirona is single-engine, in that it’s slightly more efficient than running multiple engines. And efficiency is increasingly important, not just as a measure of cost, but also for environmental reasons.

The second interesting point is that all three of the boats choose not to run generators 24×7, which used to be the common case on larger commercial boats. Instead, all of their power is generated using the main engine. Again, the same decision we’ve made on Dirona and for exactly the same reason. Rather than a shaft generator on Dirona though, we instead use two 190A at 24V alternators on the main engine, pictured above.

The labor and cost of additional maintenance when running the generaters 24×7 in addition to the main engine is material. For example, if we were running the generator 24×7 on our longest ocean crossing rather than using the main engine for all on-board power needs, we would have had to change the generator engine oil twice when underway and yet again soon after arriving. It’s actually a relevant cost and hassle.

Another reason to generate power from the main engine is that engines in all boats, but especially single-engine boats, have to be sized large enough for their biggest need. So an ice-class boat needs to have a fair amount of horsepower available, especially when pulling away from a stop and just getting underway. But for the vast majority of the time, the ship doesn’t need all the power of the engine. So using the main engine, that is effectively underutilized or not fully utilized, to generate power makes a lot of sense.


Donso Deep Water Harbour

Besides the ships, we also were impressed with the Donso Deep Water Harbour, completed in May of 2018 by SF Marina of Gothenburg, Sweden. The harbor is a floating concrete pontoon providing 755 ft (230m) of docking space. The main pontoon is 328ft (100m) by 33 ft (10m) and weighs almost 800 tons, with the whole works anchored by a 36-ton anchor using 2,600 feet (800 m) of 2-inch (50 mm) diameter cable. A key feature of the deep water harbour is a 55-foot (17m) draft limit, compared to 20 feet (6m) at other islands in the area.

We were impressed that an anchored, floating concrete pontoon could support such large ships. After our brush with disaster in Richards Bay, South Africa, where the anchored pontoons accordioned in an intense storm, we’ve been leery of docks without pilings. After seeing the Donso Deep Water Harbour, it’s clear that anchored pontoons can work very well if properly engineered.


A Memorable Day

We had an incredible day in Donso touring the two product and chemical tankers Ramanda and Fure Ven, and the pelagic trawler Ceton. All three are very modern boats focusing on fuel-efficiency, low emissions, and the ability to operate with considerable automation allowing safe operation with relatively small crews. Thank you to Alvtank, Gifico and Furetank Group for making their ships available for tour, and to the friendly and knowledgeable crews on each who answered our many questions and explained their ship’s design and operation.

Jennifer and I would also like to especially thank our longtime blog reader Torbjorn Curtsson of Stockholm who knows what we like and first made us aware these boats would be available to tour at Donso. Without Torbjorn’s heads up we wouldn’t have known about this event. Spending time on these boats and chatting in details with many crew members will be one of the highlights of this summer’s adventures.

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6 comments on “Oil Tanker Tour
  1. Tim Kohn says:

    Hi James, Your high-amp main engine configuration reminded me of this “smart alternator”:


    Do you have any thoughts? It seems to meet the simplicity bar except for the sophisticated voltage regulator controller.

    My single-engine 37′ trawler is generator-free and I’d love to stay that way, but even with judicious power consumption by my family of four, we’re only good for about 40 hours at anchor.

    • Hey Tim! Good hearing from you. Yes, Jen and I spent time with Nigel Calder discussing this work at last year’s METS and I spent quite a while going through the details with Will Godfrey of Triskel Marine. He’s one of the engineers on the project:

      https://mvdirona.com/2018/12/mets-2018/ (search down to Integrel Marine for more detail.

      We’ve met with Ken and Alison Whittamore who own Triskel Marine (Integral Marine is a Triskel Marine subsidiary).

      https://mvdirona.com/2019/04/amsterdam-visitors/ (search down to Triskel Marine)

      I’ve spent quite a bit of time with Ken Wittamore on board Ken and Alison’s boat and I’m pretty impressed. They have thought through the details well. Really high quality control systems work and a well built and very durable alternator. They aren’t far away from you so you should drop by and visit. I can introduce you if you want to dig deeper.

      We take a similar approach on Dirona where we have 9kw of alternators on our main engine:

      https://mvdirona.com/2014/08/a-more-flexible-power-system-for-dirona/ (picture of the dual alternator setup)
      https://mvdirona.com/2018/01/two-generators-when-you-only-have-one/ (details on using the main engine as a backup alternator)

      Our solution is somewhat simpler in that we have a 266HP engine where the around 20HP alternator load isn’t that large. But, on smaller engines, this requires much more care and Triskel has thought it through in detail and I like there solution.

      • Tim Kohn says:

        Thanks, James. Super helpful! BTW, I just watched Peter’s network tech re:invent keynote and got a little wistful :-)

        Since I have a 380HP engine that is rarely loaded, it sounds like I should just mount a good high-amp alternator (or two) with a good voltage regulator to achieve the same result (plus more battery capacity). How does engine RPM affect alternator output? IOW, would I get good current at idle during those painfully inefficient times when I need a charge and the boat’s not underway?

        • Yeah, Peter did an awesome job at re:Invent.

          The downside of very high output alternators is the produce quite a bit of heat and so RPM does matter. A super common alternator failure mode is charging near full output at low RPM. The low RPM means low fan speed and they overheat and fail. Over the years I’ve learned that running alternators much higher than 225F to 240F is very high risk but these big 190A Balmars I’m using are absolute tanks. As an experiment, I let one run to max temp which is around 300 to 310F and it ran for years like that so I don’t limit the output from either anymore.

          But even though some can stand it, I recommend using at least 1200 RPM to ensure alternators are getting the cooling air they need. When ours is being used as a backup generator rather than a propulsion engine, we run it at 1300.

          Two more thing to keep in mind: 1) make sure that the pulley ratio is right (max engine RPM should have the alternator close to but not over the max alternator RPM), 2) use a serpentine belt (if you have to use V-belts, larger alternators will require dual belt and dual belt is a hassle — go serpentine if you can).

  2. John S. says:

    Wow, those ships are incredible. Thank you for explaining the intricacies of how those ships can operate safely on one engine and one shaft. I’m amazed they can incorporate a separate LNG fuel system and still operate economically — I would guess there was a considerable added cost to build the ships with a separate LNG system. Fascinating how diesel fuel is used as a spark plug when the ship runs on LNG.

    • Yes, I agree. They are very focused on both fuel efficiency and lowering emissions in incredible and they have come up with innovative approaches of getting the efficiency of single engine while providing the reliability of twins and the low emissions of running on LNG with the flexibility to run diesel or even heavy oil. The uplift of running gas is substantial requiring special tanks, special dual fuel engines, and safety features like the ability to flood the engine room with inert gas. The upside for the operator is they are welcome in all ports whereas heavy oil burners aren’t and even some diesel burners aren’t unless they are running ultra-low sulfur fuel.

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