“Experience with naval machinery and equipment has emphasized the importance of instrumentation and the records kept of hourly readings.”
– Standard Submarine Operations and Regulations Manual
Complete, accurate, precise, consistent and legible records are required to enable watchstanders, supervisors and off-ship analysts to monitor the performance of increasingly complex interrelationships among a myriad of mechanical and electronic systems onboard today’s and tomorrow’s naval vessels. Computer technology, coupled with supervisory attention-to-detail, operational and technical knowledge and experience can assist in, and even relieve some of the analytical burden of making proper and adequate assessments of these complex relationships. The United Parcel Service (UPS) manufactures and uses an electronic notepad, called a Delivery Information Access Device (DIAD), a facsimile of which may be used as an interface between a watch-stander and a shipborne local area network (LAN) to conduct computer analysis and/or graphical display of component or system performance.
UPS delivery personnel use the DIAD to store information on each package they take in their trucks to include address, route, account billing information, inventory, etc. A proposed shipboard scenario involves the use a DIAD-like clipboard on which each watchstander enters log readings via an alphanumeric keypad. Upon completion of his round, the watchstander would download the data to the LAN at a connection on his watchstation. Then, with a predetermined amount of control, the watchstander could recall the data in a spreadsheet and/or graphical format to view the past data and any trends on a screen at his watchstation. Supervisors would also have access to screens throughout the ship and perhaps greater levels of control for more thorough analysis. The DIAD also allows use of an electronic pen whereby supervisors could initial or sign for review of the records.
A review for trends, both manual and computer-aided, at the time of recording hourly readings may indicate a system change which can be diagnosed and rectified before the situation deteriorated into a casualty. Computer-aided analysis may enable the watcbstander to catch a subtly degrading system trend, otherwise unnoticed.
The following example shows a comparison at current log-taking policy with the proposed computer analysis. Keep in mind, too, that logs are presently handwritten, and therefore, in varying degrees of legibility.
Table 1 depicts what might be a typical set of log readings over a 24 hour period for a generic tank level.
Table 1. 24 Hour Log of Tank Level
|Time||Tank Level (Gal)||Time||Tank Level (Gal)|
|Min 1000||Min 1000|
Figure 1 shows how the tank level varies over the 24 hour period and the minimum and maximum specifications allowed. Less mental exercise is required to see the trends and out of specification conditions.
How does your mental picture compare with the graph? Did you draw the minimum and maximum specification lines? How does the fill rate of the system compare with the capacity of the filling system? (Do you know the fill rate of the filling system?) Does the use rate exceed a mandated use rate? (Are there any onboard systems for which a mandated use rate might be applica-ble?) Using advance regression techniques, statistical process controls could be used to improve the performance of specific systems onboard.
With appropriate software, further analysis could be conducted on specific log readings and trends, which, in tum, could be compared with a periodically updated database of similar system or component performance(s) on other boats, or from DEVRON 12, for instance, to monitor for impending failure (tangent to potential PMS periodicity changes).
By-products of this type system are abundant: more legible data recording, instantaneous comparative analysis between current and previous readings, immediate availability of all ship’s systems’ performance, both individual and collective, to supervisors, ability to send electronic records off-ship while at sea for more exhaus-tive and educated analysis, and reduction of paperwork, among many others.
Using a device similar to UPS’s DIAD in conjunction with a shipwide LAN is just one step toward enhancing watchstander alertness and performance as well as providing for improved system performance and lifetime-a savings issue.