After we have in an earlier post looked at some recent two-stroke main engine crankshaft repair assignments that we have carried out on ships in operation, we now move the focus further towards the after end of the ship.
In this post we look at how we routinely support new building shipyards with shaft line alignment and machining work.
Read more about our recent two-stroke crankshaft work assignments
Shaft Line Work for VLCS in China: Recent Success Stories
At QuantiServ, we routinely perform essential alignment and machining work on behalf of shipyards in China on new vessels under construction. We do this for a wide range of vessels.
In this post we look at some of the very largest vessels that we work on, namely Very Large Container Ships (VLCS). These are vessels with a capacity to simultaneously carry up to 24’000 standard, 20-foot shipping containers. Typically, these ships are 400 meters long, about 62 meters wide and have a draught of about 16 meters when fully loaded.
These colossal vessels typically feature shaft lines that span between 80 to 100 meters in length, with shaft diameters ranging from 900 mm to over 1000 mm. These impressive dimensions are imperative due to the massive power of these ships’ main engines, which can reach up to 60,000 kW. This is equivalent to the power of 600 average-sized cars.1
Case 1: Stern Tube Bearing Failure Recovery
In one notable project, we assisted a shipyard and shipowner after a stern tube bearing failure on a recently delivered VLCS. While underway, the ship’s stern tube bearing suddenly overheated, reaching temperatures of well over 200 ℃, leading to the complete destruction of the bearing bush. The sudden heat increase also led to cracks in the propeller shaft.
Obviously, this critical issue required prompt action to prevent extensive downtime. Our team efficiently assisted the shipyard to replace the bearing bushes and machined the shaft in-situ to remove the cracks in its surface. Our ability to machine the shaft in-situ eliminated the need to withdraw it, which would have been a time consuming and risky operation. This approach thus not only saved valuable time and therefore minimized operational losses. It also reduced the risk of anything going wrong during the delicate propeller and shaft removal and reinstallation work and ensured that the vessel could return to service swiftly.
After completion of our work, the shaft bearing temperature was recorded at just 32 ℃, no more than 13 ℃ Celsius above the surrounding sea water temperature, which is an excellent result!
Case 2: Construction Phase Alignment and Line-Boring
During the construction of another VLCS, our laser alignment checks revealed that the newly delivered and installed stern tube suffered from ovality and incorrect slope, posing a significant threat to the vessel’s long-term, safe performance. Once our team brought this information to the attention of the shipyard and proposed to line bore the stern tube, the shipyard, classification society and shipowner quickly agreed to our solution.
By employing precise in-situ line boring techniques, we corrected these issues, ensuring that the ship’s shaft line will perform optimally for many years to come. This intervention during the ship’s build phase highlights our commitment to quality and foresight.
Case 3: Long-standing cooperation
QuantiServ has long been a trusted partner for shipyards worldwide. We are often involved from the early stages of new-building projects, providing technical expertise and precision machining services. For example in China we have ongoing agreements with several major shipyards, whereby we carry out laser alignment and inspection services for entire series of vessels.
During the summer of 2024, we for example completed shaft alignment services for the sixth and final delivery in a series of large, LNG-fueled ships built for a major container shipping line. All six ships are now in operation and are performing very well.
Demonstrating Expertise Across the Industry
All three cases were undertaken in China on some of the worlds’ very largest and newest ships, that will be owned and operated by three of the world’s largest container shipping lines. They involved different shipyards and different classification societies. This diverse customer base underscores the broad acceptance and trust in QuantiServ’s expertise and know-how within the maritime industry.
The three ships highlighted in this post are all either LNG-powered or are able to operate on more than one fuel. As such, they contribute to the decarbonisation of the marine industry, which is a goal that QuantiServ very much supports. Furthermore, QuantiServ is proud to contribute to the reliability and efficiency of these magnificent vessels, ensuring they meet the highest standards of operational performance and safety.
1 In 2018, the most recent year for which data are available, the average car in the European Union was fitted with an engine that was able to produce 98 kW of power.
