Page 31: of Maritime Reporter Magazine (February 2024)

EAL AND STERN TUBE DAMAGES “Our recommendations “A good bearing are simple. Please design is have good control over important.” your oil quality in the primary barrier, the aft – Øystein Åsheim Alnes sealing system,”

Head of section for

Propulsion and Steering, – Arun Sethumadhavan

DNV

Senior Principal Engineer,

DNV

Photo Courtesy DNV

Photo Courtesy DNV stalling a proactive warning system that alerts the crew to any quite ‘relaxed’ for EALs.” concerning rate-of-rise in bearing temperature or if the draft Still, the Gard data shows claims in excess of $5,000 in- of the vessel could leave the propeller partially immersed. In creasing in number up to 2020 and then declining: from 134 addition, on older vessels DNV recommends that EAL viscos- in 2020, to 118 in 2021 and 87 in 2022 – a noteworthy decline. ity should be increased one grade up from the design speci? - Ship repairs are the day-to-day concern of UK-based Ma- cations of the installation. rine and Industrial Transmissions, and the company’s engi- “Our recommendations are simple. Please have good con- neers don’t see any current trends in the causes of stern tube trol over your oil quality in the primary barrier, the aft sealing damage. A recent case study demonstrates what can go wrong system,” says DNV Senior Principal Engineer Arun Sethu- though: upon interviewing the Chief Engineer of a vessel madhavan. “The solutions are not intrusive.” they were recently called out to, it was discovered that the

Current sentiment seems to bear that out. Manufacturer Pa- stern bearings had overheated due to loss of lubricating ? uid. nolin noted strong support for EALs at a 2023 trade show. This caused the bearing faces to become seized to the shaft “As the shipping industry looks toward the future, sustain- momentarily, leading to accelerated bearing wear, with the ability is becoming a priority. In fact, it was the overriding bearing material migrating through the lubrication system. theme at Sea Asia.” Rudder, propeller and shaft needed to be removed in dry dock

However, insurer Gard remains concerned about EAL fail- before the required repairs could be completed.

ure, and company analysts voiced them in October 2023 when “Design fault” was a common category assigned to Gard they released an analysis of the last 10 years of claims. One claims, which could indicate shipyard errors unrelated to lu- of the things they noted was the IACS suggested limit of 1% bricant choice.

water being allowable: “The speed of hydrolysis depends on DNV Head of section for Propulsion and Steering in Oslo, various factors, for example, chemistry of the oil, tempera- Øystein Åsheim Alnes explains one of the key challenges. Dif- ture and additives. The most important factor, however, is the ferent operating conditions mean different loading conditions quantity of sea water present in the lubricant. The 1% limit is on different parts of the aft stern tube bearing. “The weight

ENDLESS SUPPLY OF MARINE HARDWARE ! &"$)$?""?!!&"$l • New, Used and Rental Options Available

AUTHORIZED YOKOHAMA • New Harness Installation 0r Harness Repair with Quick Turnaround

FENDER DISTRIBUTOR • Foam and Pneumatic Fenders Available

NEW & USED LARGEST INVENTORY IN THE USA

IN STOCK &

READY TO SHIP • Anchors • b?m]v • Hardware • ou7-]; • Dock • Buoys

WORLDWIDE • Chains • $o?bm] • Wire Rope • Blocks • Fenders • Spill Boom 24/7 ?????ƒƒƒ??????!!&"$l www.marinelink.com 31

MR #2 (18-33).indd 31 2/6/2024 9:19:35 AM