Long Term Performance of Mooring Lines Made with Spectra® Fiber

In 1990, Whitehill Manufacturing produced one of the earliest mooring ropes made with Spectra^reg fiber for a Jones Act tanker operator. The lines were tested aboard a 60 k dwt tanker dedicated in ship-to-ship lightering service in San Francisco Bay since this vessel docked and undocked 3 to 5 times more frequently than a typical tanker. Therefore, it provided an ideal accelerated test case to evaluate the endurance of synthetic lines in a pier-side mooring application. Initial test results reflecting 8 years of service were presented at the 1998 DOT MTS conference. The breaking strength was determined to be excellent and the lines remained in service. In May 2003, these same lines were retired after 13 years of service. One of the retired lines was returned to Whitehill in its entirety. Sample sections were removed and tested to determine residual breaking strength characteristics as a function of position on the winch drum. Spectra^reg fiber was removed from positions between each of the test samples and sent to Honeywell for microscopic analysis. Results on retained breaking strength are presented as well as a discussion of the mechanisms affecting the long term life of mooring lines containing fiber made from high modulus polyethylene (HMPE)