Page 30: of Maritime Reporter Magazine (February 2024)

REPAIR

Photo courtesy Marine and Industrial Transmissions

STERN TUBE

DAMAGE

DECLINING?

It might be easy to blame EALs, but the ongoing causes of stern tube damage are varied, and possibly declining.

By Wendy Laursen nvironmentally Acceptable lubricants (EALs) gained market traction with the introduction of

US VGP regulations in 2013. Since then, DNV has observed two major trends. The ? rst, starting

E in 2013 was early life damage, either during sea trials or within the ? rst ? ve years of operation, where aft stern tube bearings typically failed under extreme load conditions.

Then from around 2018, vessels of about 10 years of age and above started experiencing bearing damage, with many of them having lubricant contamination problems. The affected vessels were often delivered with mineral oil then converted to EALs and subsequently suffered sealing problems.

DNV rules support the use of mineral lubricants, EALs and water lubrication and are complemented by relevant technical publications with recommendations to overcome known is- sues. In its November 2023 guidance, DNV recommended in-

Photo courtesy Marine and Industrial Transmissions 30 Maritime Reporter & Engineering News • February 2024

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