Proceedings magazine is a communication tool for the Coast Guard's Marine Safety & Security Council. Each quarterly magazine focuses on a specific theme of interest to the marine industry.
Issue link: http://uscgproceedings.epubxp.com/i/617100
24 Proceedings Winter 2015–2016 www.uscg.mil/proceedings • depth under keel; • main alarms; • rudder order and response; • engine order and response; • watertight and fre doors status; • other sensor data. The recorded data is stored on the server's hard drive and in a protective capsule (for an S-VDR system) or a fixed weather deck-mounted capsule (for a VDR system). Investi- gators must recognize that the digital recorded information is proprietary and therefore requires the necessary playback software. Additionally, some playback software requires a password. On vessels not ftted with an integrated bridge system or VDR, other equipment can provide essential recorded infor- mation. This equipment includes: • an electronic chart display and information system (ECDIS), which displays information from electronic navigational charts and integrates position information from the GPS or DGPS and other navigational sensors, such as radar, echo-sounder, or the Automatic Identif- cation System (AIS). • GPS or DGPS can be a resource in the absence of a VDR or ECDIS. These systems provide a list of waypoints and the track history used in the voyage, which is extremely helpful data to determine a ship's position and move- ments prior to an incident. • As with GPS or DGPS, AIS is a useful tool in terms of electronic evidence collection. Some AIS systems have data recording capabilities that provide information about the ship's and other vessels' movements in the area, which is also useful in identifying witnesses. However, AIS is prone to inaccuracies and errors in various data felds, so investigators should take that into consideration. • Other basic individual systems such as course recorders, automatic radar plotting aids, radar consoles, and depth sounders may also hold relevant information. Dynamic Positioning Incident Basics When diagnosing an incident involving dynamic position- ing (DP), understanding the incident and vessel platform is an essential step in identifying the probable failure. DP technology enables a vessel to maintain its position and heading using sophisticated positioning systems and other sensors as well as its own power plant, thrusters, and pro- pellers. Extrapolating and interpreting the information from the monitoring systems, such as an external data logger and/or data stored on the operator station (main machine interface) is key. Investigators should familiarize themselves with the equip- ment description and software details in the original, sub- sequent, and last failure mode effect analysis (FMEA) trial report. Fundamental questions include: • Was the vessel in proper DP setup/configuration, matching the approved FMEA confguration? Check for changes. • Do the hardware details match? • Was the software upgraded? • Was a new FMEA trial completed with the vessel's clas- sifcation society? If so, examine the automation alarm panel logs and review for previous suspended, blocked, and inhibited alarms. • Did weather cause the vessel to exceed its working enve- lope? • Was there external component failure or operator error? • Was the vessel redundancy correct for the assigned job? • Was there a failure of a key external system, like a sen- sor or position reference system? • In fair and foul weather conditions, was the failure to stay on station caused by a backup not engaging or a failure of redundant power supplies to controllers or sensors? Engineering and Propulsion Incident Basics Investigators should also recognize that failures in dynamic positioning may not just be a result of a localized system failure, so analyzing propulsion and machinery failures and understanding the technical basics of engineering systems is essential. Dynamic positioning system fowchart. U.S. Coast Guard graphic.