Utilizing a stern tube allows the ship to continue going forward through the water. Recent developments have resulted in the unveiling of a revolutionary senseless ship design that holds the potential to improve both environmental and operational outcomes substantially.
(Photo : Pexels/Diogo Miranda)
Where are Stern Tubes Used?
A hollow tube known as the stern tube is responsible for holding the shaft that is used to connect the engine to the propeller. Aside from being referred to as the tail shaft or the propeller shaft, this particular shaft is constructed from either cast iron or mild steel for the tube.
Moreover, the sealing mechanisms that are designed to prevent water from leaking into the ocean are housed within the stern tube. This set-up consists of oil chambers, rubber seals, and liners that revolve in tandem with the propeller shaft. Besides preventing water from leaking inside the ship, it is also responsible for preventing oil from leaking into the ocean.
It can be found toward the back of the ship, often known as the aft end. While the stern frame is responsible for supporting the rear portion of the tube, the aft peak bulkhead is accountable for supporting the front portion of the tube.
In most cases, the tube makes its entrance into the combustion room of the ship, which is located on the lowest deck. The size and other details of the stern tube are set by things like how the engines are arranged, how much power is needed, the size of the propeller shaft, and how the seals are set up.
However, the oil used for stern tube lubrication contributes to the pollution of the oceans at a rate of more than eight million litres per year. Mr Chris Leontopoulos, Vice President of Technology for EMEA at ABS, stated that the stern tubeless ship design modifications that the group has offered have the potential to create a vessel that is both environmentally and commercially optimal, all while reducing operational costs by hundreds of thousands of dollars. Additionally, this is accomplished without altering the hull lines or the pre-existing norms and regulations of the class.
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Cost and Benefits of Stern Tubeless Ship Design
An ocean-lubricated bearing, a Wartsila forward shaft seal, a Water Quality Package, and a bulkhead seal are all included in the design of the stern tubeless vessel. One of the most critical aspects of the design is that it incorporates a dry internal examination chamber aft of the engine room, which is typically occupied by the stern tube.
Stiffeners were cut down, and a hole was cut into the bulkhead in order to generate this new space, which is large enough for engineers to set themselves up. At the same time, they maintain or replace components of the propeller shaft while the ship is in motion.
According to Chris Leontopoulos, who works with Blue Ocean Alliance, all future newbuild boats of any kind should be constructed without stern tubes and with a propellant shaft bearing system that is lubricated with seawater. Upon viewing a graphic that contrasted a ship with and without a stern tube, the technical distinctions became readily apparent immediately. He also stated that the stern tubeless ship eliminates the requirement to realign the shaft throughout the lifetime of the vessel. This eliminates the possibility of the shaft becoming damaged or indented, which may lead to significant amounts of downtime and expenditure.
On the other hand, although the expected capital expenditures for extra components might add around $10,000 to $30,000 to the cost of a new build, Mr Leontopoulos admitted that this was the case as he continued to outline the benefits of a ship that did not include stern tubes. Due to the decreased amount of money spent on operations, the return on investment (ROI) can be achieved in a short amount of time due to the lower operating expenditure.
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