Dry-docking cost reduction through propulsion monitoring


Wärtsilä claims that condition monitoring services can extend the lifecycle of thrusters for tug and offshore vessel operators.

Analysis of performance data enables engineers to identify condition issues, predict the timing of failures and extend the period between overhauls. This lowers operating costs for owners and reduces the number of dry-docking visits for workboats and vessels.

Wärtsilä secured its first customer for an advanced performance-based service agreement when it signed a deal with drilling rig and ship operator Transocean in July. Together they intend to optimise the maintenance of Wärtsilä thrusters installed within Transocean’s fleet of deep-water drilling systems, using Wärtsilä’s propulsion condition monitoring service (PCMS), which collects performance data from the thrusters and delivers it to Wärtsilä’s condition-based maintenance (CBM) centre for analysis.

Wärtsilä believes that this type of agreement can be used by owners of tugs and offshore support vessels to improve the reliability of thrusters. The PCMS provides real-time advice and periodic reports concerning the condition of the machinery. This leads to greater availability than could be realised through conventional planned maintenance.

Through condition monitoring, owners can base their operational decisions on the actual condition of the equipment and assess risks based on the projected reliability of the propulsion equipment.
Vessel operators can perform overhauls only when they are actually needed, rather than carrying them out periodically. The company claims that owners can extend the time between thruster overhauls from five years to a maximum of ten years, based upon the actual status of the thrusters.

This is because tug operators would be informed of faults well before they lead to breakdowns and conditions that generate excess wear on the equipment can be avoided.

These expectations will be tested during the contract with Transocean, which will involve service engineers analysing the data to determine when thrusters will need servicing in a dry dock. Engineers will produce flexible maintenance schedules for each piece of equipment based on the actual condition of the device.

Wärtsilä and Transocean expect that this will reduce dry-docking requirements as they anticipate each thruster will be overhauled just once during the 13-year agreement period. This covers five semi-submersible rigs and one drillship, each of which has six to eight thrusters.

Other engine room machinery can be monitored in a similar method to thrusters with comparable results, if the needed data is available and accessible.

Wärtsilä’s propulsion condition monitoring service combines sensory data, such as vibration, pressure and temperature, with the operational parameters of the propulsion equipment, such as pitch, steering feedback and set points. In addition, it takes into consideration the nautical parameters, such as vessel speed, rate of turn and draught, giving the customer the ability to accurately relate sensory data to the actual operating conditions.

The system has been developed to detect the operational state of the propulsion equipment through real-time comparisons of parameters from multiple sources. Data is captured and sent over the vessel’s satellite communications or links to a 3G or 4G mobile network if close enough to shore.