Capstan Dynamic Test Method Improves Efficiency and Safety at Norfolk Naval Shipyard

Photo By Daniel DeAngelis | Code 740 Field Gang Work Leader James Buchanan acts as a line handler to regulate free end line tension as the capstan rotation begins. Free end tension was modulated to reach and maintain tension on the load line which was monitored with a wireless load cell. A major point of the evaluation was controlling the load line tension in the kinetic friction region of the capstan head.  

UNITED STATES

03.08.2024

Story by Susanne Greene 

Norfolk Naval Shipyard

Norfolk Naval Shipyard (NNSY) has developed a new Capstan Dynamic Test which will save time, reduce spending, and improve workforce safety.
Capstans are used for pulling on the ropes when mooring a ship to a pier. During a repair or overhaul, the ability of the capstan to operate under load requires testing. This is known as a Capstan Dynamic Test.
During the test, each motor and capstan drum need to be powered and under the rated loading conditions for each speed and direction for a specified period of time. In the past, this was achieved by lifting and lowering weights over the side of the ship.
As NNSY’s Test Engineering Organization, Code 246 is working on an initiative to improve operational testing on Carrier, Volplane, Nuclear (CVN) mooring and warping capstans. The current method of testing is all day for one capstan. The initial Capstan Dynamic Test Method was completed in eight hours for one capstan. Future testing is expected to take only six hours per capstan.
“The objective of our evaluation was to determine what conditions would be required to maintain control of tension over a 15-minute period, how much wear or abrasion would the rope suffer during the test, and what amount of cooling would be required,” said NNSY Hull Mechanical and Electrical Chief Test Engineer Kevin Brown. “The evaluation was designed to control each variable and record the results in order to optimize the conditions.”
Brown continued, “It was determined with the help of Codes 982 and 900F.32 that land-based capstans could be used to evaluate the new test method. This allowed for better flexibility in both physical access and schedule since it was not directly associated with a project.”
Several codes work together to conduct the tests. Code 246 leads the testing and works with Lifting and Handling Department (Code 700) as well as Code 263’s Surface Ship Mechanical Branch, Code 300 (Operations), Code 982’s Waterfront Support Branch, Code 900F’s Dry Docks and Piers (900F.32) and Code 990 Temporary Services Shops 89 and 99. Typically, shipboard testing requires 20 people, but the new method will only require five.
Based on the knowledge gained from the initial evaluation in January, Code 246 intends to perform one additional round of land-based testing for assurance to transition to shipboard testing. Several factors believed to have the greatest influence on the control of load line tension will need be revised to duplicate shipboard conditions.
“The new test method stands to remove risk associated with suspended loads, saves time and money on the shipboard preparation required for the rope path, and reduces impact on the pier during the test evolution,” said Brown.

• Date Taken: 03.08.2024
• Date Posted: 03.28.2024 08:34
• Story ID: 467219
• Location: US