October 20th 2014 saw an incident where a Russian vessel went disabled due to an engine room fire which left it without propulsion. This warrants further analysis as most modern vessels are just as prone to malfunction as the older ones; hindering maritime operations and creating more losses for the operator and the crew of said vessel. Finally, it is worth mentioning that a disabled vessel, according to US law is; “a ship unable to sail efficiently or is not in a seaworthy state due to either engine trouble, lack of officers and crew along with damage to hull or the ship’s gear.”
Firstly, what makes a vessel move? Engines and propulsion systems thus beginning our analysis from the vital organs. In the case of the Russian vessel above, the engine itself was damaged since engine room fire disabled the engine and propulsion mechanisms. Beginning the analysis it is worth knowing that a propulsion system is chosen for the engine size and horse power; not considering the propeller therefore promoting inefficiency which also guarantees failure in long term. Signs of a possible malfunction and/or incompatibility with engine includes a slow steam speed, issues in gaining or maintaining trawling speeds, high levels of vibration not attributed to engines, generators and other onboard machinery, little or no gain in vessel speed with RPM/Revolutions Per Minute increase with the engine itself also unable to reach target RPM. Along with black smoke being expelled through the exhaust with chronic blade damage not related to striking underwater objects.
Another feature of a malfunctioning propulsion system, due to abundance of rotating parts inside an engine, is vibration therefore carry consequences. Vibration, from experience also happen due to friction between moving or unfitting parts therefore remedied with alignment tools and automatic lubricators applied during system construction where components themselves are refined and upgraded to increase resistance to vibration. However, vibration will never be fully eliminated. Measures adopted so far were vibration monitoring equipment during marine operations as vibrations are known to be the main source of propulsion failures according to Hansfordsensors.com (2014.) Such equipment pinpoints and examines key causes for vibration.
Vibration monitoring equipment give early warnings which enable engineers to take actions prior to a more serious issue. Machinery such as fans and motors running out of alignment result in vibration which in-turn leads to excessive wear on the machines, reducing efficiency. However, on larger vessels, most common in modern maritime surveyors cannot inspect more than 20% equipment yearly; leaving many machine parts un-examined therefore warranting more failures aboard which in turn will threat crew as well.
Another anomalous fact of vessel machinery malfunction is that most malfunctions are induced by maintenance where regular assembly and disassembly would increase likelihood of said malfunction. In contrast, condition monitoring allows for better maintenance and efficient operations. Concluding with the fact that vibration monitoring equipment is the first essential solution to vessel machinery errors.
However, as with every idea there is a challenge/flaw as readings can change drastically during different phases of the maritime operation where readings on vibration sensors can vary from when a ship is in port to where the vessel is actually at sea. There is a solution to this where engineers should consider vibration levels and frequency range to be measured in order to calibrate the sensors according to proper parameters. Further considerations include atmosphere and its combustible index (is it combustible?) and possible weight constraints; along with the fact that there is no earth present a challenge in its own right.
Upon selection of appropriate sensors and detectors placement is equally important in performance. Sensors should be located close to the source of vibration while being mounted on a flat, smooth and unpainted surface which is larger than the base of the sensor itself; free from grease and oil. Data collected is analysed and processed by engineers therefore creating a picture of the error.
Leading back to propulsion directly, there are other measures to improve efficiency of the machinery with regards to capital investment. Obviously starting from seasonal maintenance before, during and after the season; including inspection and replacement of all filters and lubricants along with attention to the shafting arrangement. As mentioned above, maintenance has 2x sides so this should be approached from a perspective of fixing detected faults rather than disassembly and direct component replacement.
The second measure is somewhat controversial where component replacement is required, opposing the above approach. However, it involves replacing a defunct fixed pitch propeller as most errors occur due to improper propeller selection; similar nature to wrong choice of propulsion system against engine size. Characters of an unsuitable propeller characteristics involving diameter, pitch, skew and number of blades where the most efficiency can be achieved by increasing diameter. Installation of a nozzle ahead or around the propeller as they capture positively altering water flows towards the propeller; typically increasing bollard pull, steaming speed and overall propulsive efficiency.
A vessel operation, also is as efficient as its machine operators therefore more control should be placed on important machinery thus warrants installation of more control via a controllable pitch propeller/CCP. A CCP contains machinery giving operator the control of altering the pitch at will which optimises towing and steaming speeds.
Finally, alterations to engine and transmission with regards to operational requirements; if the vessel is under or over-powered it means that it is not operating at optimal RPM; remedied by alterations to gearbox.
