Replaceable Inserts for Ship's Line Handling Chocks

The Navy seeks an innovative solution to decrease the high expense associated with replacing ship mooring lines due to the excessive wear that occurs when chaffed across rough operating surfaces such as shipboard mooring chocks. Nelson Engineering Company was awarded a Phase I Small Business Innovation Research (SBIR) contract to investigate the capabilities of Nylatron(Registered) NSM, a new self-lubricating polymer with high surface smoothness and wear resiliency, and its potential for use in a chock insert designed to significantly reduce wear on mooring lines. Physical and chemical material tests were conducted on Nylatron(Registered) NSM, including exposing samples to abrasive and loading conditions designed to simulate chock insert operating conditions and subjecting samples to a simulated outdoor corrosive marine environment. Results show that Nylatron(Registered) NSM: 1) Does not chemically alter or break down when exposed to a simulated marine environment or prolonged UV exposure. 2) Is chemically inert. 3) Maintains an exceptionally smooth surface and creates minimal particular material when abraded. 4) Performs elastically under operational conditions and plastically deforms under mooring line safety factor loading conditions without cracking. A Nylatron(Registered) NSM full scale two-piece insert prototype was developed to demonstrate constructability and facilitate attachment method concept visualization. The initial cost analysis indicates significant program savings (approximately $3,000,000 per year for the Destroyer fleet.

The original document contains color images. Sponsored in part by the Naval Sea System Command.