Thordon Bearings: Seawater-lubricated propeller shaft bearings here to stay

Burlington: Thordon Bearings has welcomed the recent introduction of a new classification society notation allowing extended inspection periods for propeller shafts using seawater-lubricated bearings.

DNV GL’s new voluntary TMON notation for open loop water lubricated propeller shafts follows similar rule revisions by Lloyd’s Register (LR), Bureau Veritas (BV) and the China Classification Society (CCS).

DNV GL’s new rules mean that propeller shafts operating water-lubricated bearings no longer need to be withdrawn for inspection every five years. There will be no pre-determined intervals between shaft withdrawal surveys.”

The five-year shaft inspection rules previously stipulated in most shaft condition monitoring notations were a major deterrent to the wider take-up of the water lubricated system, Thordon’s president and ceo Terry McGowan reckons, but now DNV GL has revised its rules the Thordon boss says his fims can present a viable and proven alternative to oil-lubricated propeller shafts.

The condition-monitoring-based survey process, which waives the requirement for the withdrawal of the tail-shaft at pre-determined intervals, also enables operators to consider seawater lubricated systems as a compatible alternative to meeting US Environmental Protection Agency’s Vessel General Permit [VGP] requirements.

“Seawater-lubricated propeller shaft bearings are here to stay,” McGowan tells Maritime CEO, “so it is appropriate that classification societies have now developed notations that are in keeping with market demand for environmentally safe, cost-effective propulsion solutions. These systems are becoming more popular with shipowners amidst mounting pressure for regulators to develop rules that further safeguard the marine environment.”