In 2017, the Indian Coast Guard ship Sagar was brought into port for routine maintenance when engineers discovered severe defects in the ship’s port shaft line. Specifically, composite bearings had signs of extreme premature wear, and had been failing repeatedly since the ship’s commissioning in 1999. Additional damage included deep grooves on the shaft that obstructed the intermediate bracket on the forward and aft sides, and forced the propeller shaft out of alignment to rest on the Aft A bracket.
Lignum Vitae North America was engaged to assess the issues and engineer a solution that guaranteed mission readiness in extreme operating conditions for this patrol vessel, which provides critical maritime support to Indian assets.
Identify solution with proven results to replace unreliable composite material.
Eliminate key performance issues including composite material degradation and shaft scoring.
Address excessive wear of intermediate bracket with 21mm clearance against 6.00mm renewal clearance.
Conduct tests to compare zero clearance lignum vitae shaft line bearing performance with composite material’s 80 mm clearance against 6.00 mm renewal clearance.
Lignum vitae bearings permanently replaced existing, poorly performing composite bearings on the port shaft line.
Lignum vitae bearings have sustained satisfactory, uninterrupted performance since installation.