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www.sname.org/sname/mt redundancy groups in order to stay within WCF in the event of a particular failure. It should also be remembered that the FMEA analysis only considers a single failure. It is good practice at the design stage of the vessel to include FMEA practitioners so that ideas can be exchanged and risks are mitigated in design and not operational setup. Early collaboration also has the advantage of identifying potential issues while a change is eected on draw- ings alone and not in the physical world. e DP FMEA is the rst line of defense against a position and/or heading loss. However, even a good FMEA is only half the story. ere are also the operational and human aspects of opera- tions that introduce risk. e FMEA is a technical document. It needs to be read and understood particularly by those onboard. It denes the capability that remains should a failure occur, and with this knowledge the ves- sels operators will understand the severity of a particular failure and if any action may need to be taken. It would of course be unreason- able to expect a member of the vessels sta to remember each failure mode presented in an operational setting. With that in mind, a num- ber of support tools have been developed that support the onboard decision making process, particularly for DPOs. e DP operating manual is a support document that details practical arrangements for operating the vessel in line with an FMEA. It will consist of general systems descriptions, but not in the same detail as the FMEA. It also will detail how systems are to be set up, both in the engine room and on the bridge, before going into the DP mode. Often, it also will cover a general description of DP con- trol systems and how they are aected. DP operations manuals can vary widely from organization to organization. Often a manufactur- ers operating manual for a DP system is presented as a vessels DP operations manual, but the two are not the same. e requirements of a DP operations manual are dened by IMCA in the notice M109. e DP operations manual is a class requirement. In addition to the DP operations manual, there also are activ- ity specic operating guidelines (ASOG) or, in the case of drilling units, well specic operating guidelines (WSOG). is is a docu- ment held onboard and relates to specic operational activities. e DP FMEA and operations manuals are general ships docu- ments. ey do not address the risks of a specic activity the vessel is engaged in. e ASOG and WSOG divide operational criteria into four conditions: green?continue as normal; blue?advisory consult and assess risk; yellow?cease operation and prepare to move to safe location; and red?cease and depart. e DP operations manual should contain or reference an onboard set of DP capability plots. ese are often overlooked, but they dene the vessels ability to hold station relative to the environment. e DPO should be very familiar with its content as they tell us vessel capability under WCF conditions. A set of plots should consider the fully intact thrust case to the WCF. It should also include plots between these conditions as dened by the FMEA and appropriate redundancy groups. Further reading on capability plots can be found in IMCA M140 DP Capability Plots. A requirement of IMO MSC 645 is that periodic verifying footprints are carried out onboard to conrm DP capability is as expected. is is covered in IMCA M140. We can never eliminate all risk of a DP incident. However, an engaged crew, with a thorough understanding of quality documentation as we have outlined here, is well on the way to minimizing likelihood and managing failure outcomes of DP inci- dents. e mechanisms that have developed since the pioneering days of the early 1960s have brought us a long way. However, chal- lenges remain. Arguably, the biggest is as a result of the success of DP and the growing number of vessels using it: an industry-wide shortage of DP qualied sta, which is felt most keenly onboard. Many are of the opinion that there is a dilution of talent to a level that gives rise to risk in itself as the experience is so dispersed. MTMat Bateman is DP/vessel systems manager at Houston-based Global Maritime. Further Reading To learn more about DP systems and requirements, check out the following resources. IMCA M103 ? Guidelines for the design and operation of dynami- cally positioned vessels IMCA 113 IMO ? Guidelines for vessels with dynamically positioned systems IMCA M166 ? Guidelines on failure modes and eects analysis FMEA In addition, dependent upon the systems that are ?tted, the following IMCA guidelines will be appropriate: M109 (DP docu- mentation); M119 (Fires in machinery spaces); 128 DOVOA (Dual DGPS); M129 (CPP thrusters); M131 (Fan Beam); M141 (DGPS in DP control systems); M162 Failure modes of variable speed thrust- ers; M163 (Software control); M170 (Laser positioning system); M174 (Artemis); and M206 (Electrical power and control systems) Marine Technology Society (MTS) DP Vessel Design and Philosophy Guidelines Part 1 and 2 October 2013