Advanced Power & Propulsion Monitoring System – ‘HEMOS’
A detailed knowledge of how a vessel’s power and propulsion systems are operating gives confidence for continued safe operation. It can also help control costs and extend times between overhauls: precisely the aims of Rolls-Royce Marine’s HEMOS advanced condition monitoring system, the maritime equivalent of similar monitoring systems in the civil aircraft sector.
A few years ago Rolls-Royce fitted a prototype of ‘HEMOS’ (acronym for ‘Health & Monitoring System’) to Farstad Shipping’s offshore platform supply vessel Far Searcher, then more recently, based upon experience gained, they fitted a commercial version to the same company’s offshore anchor handler Far Scorpion.
OSV 'Far Searcher': Photo courtesy of Farstad Shipping
Advanced Condition Monitoring with HEMOS
HEMOS has the ability to record and analyse data from as many as a 'Gee Whiz' 4,500 points on board Far Scorpion as well as transmit it to shore for detailed analysis. Sensors on major items of equipment collect data on various parameters; some are in the equipment control loop and as such, form part of the ACON ship alarm and surveillance system. Other sensors on the integration control loop capture a wider range of information parameters that are not normally measured by the control system, such as oil quality and vibration measurements.
Image courtesy of Rolls Royce Marine
A service centre on shore receives all the HEMOS data transmitted from the ship, runs it through special analysis software which comes out with trend and quality information that can be interpreted by product experts to create asset health reports for the shipowner’s technical staff.
However, it is not intended to sideline the afloat staff by these means, as reportedly, analyses and reports with real-time information are also presented on board Far Scorpion’s HEMOS display. The great advantage of centralising this information is that shipowners are able to monitor one specific vessel or have an overview of their entire fleet in order to forward plan docking schedules and spare part requirements.
Apart from avoiding machinery breakdowns, the system offers considerable long term opportunities, by combining machinery data such as power developed and continuous recording of fuel consumption with navigation and weather data to improve the vessel’s overall operating efficiency and thus reduce fuel consumption and emissions.
Interestingly, data obtained from the prototype HEMOS system is also extremely useful for advanced marine propulsion research. For instance, data provided by the monitoring system installed in Far Searcher was accessed by researchers Luca Savio and Sverre Steen at Norway's NTNU and MARINTEK centres to help investigate affects on propulsion machinery of propellor air ventilation, and their report ‘Identification and Analysis of Full Scale Ventilation Events’ can be accessed here.