Stern Tube Bearing
critical
IMO Required
Bearing supporting propeller shaft in stern tube
5 yr
Class Survey
15 yr
Typical Lifetime
Typical Manufacturers
Thordon
Duramax
Wartsila
Known Models (26)
Aegir Marine (Netherlands) Oil-Free Stern Tube System
Shaft diameter 200-1,000 mm
· Seawater lubricated (zero oil to sea)
type: Complete Oil-Free Stern Tube System (Bearing + Seal)
size_range: ['AOFS-200', 'AOFS-400', 'AOFS-600', 'AOFS-800']
power_range_kw: None
variant_count_approx: 4
period_start_year: 2015
period_end_year: None
drive_type: Passive (seawater lubricated)
construction: Polymer bearing + face seal, complete system, no oil
successor_series: None
Common Failures:
- • Face seal wear from debris in seawater
- • Polymer bearing wear in silty waters
- • System air entrapment causing bearing noise
Service: Bearing clearance check at drydock. Face seal inspection at drydock. Seawater supply system filter check monthly. Zero oil consumption — no oil monitoring needed.
Spares: Aegir Marine (Heerhugowaard, Netherlands). Lead time: 4-8 weeks. Complete system engineering for retrofit available.
Blohm+Voss / Aegir Marine (Germany/Netherlands) White Metal Stern Tube Bearing
Shaft diameter 150-1,000 mm
· Oil lubricated
type: Oil-Lubricated Stern Tube Bearing (White Metal / Babbitt)
size_range: ['WM-150', 'WM-300', 'WM-500', 'WM-700', 'WM-1000']
power_range_kw: None
variant_count_approx: 5
period_start_year: 1900
period_end_year: None
drive_type: Passive (oil lubricated via stern tube oil system)
construction: White metal (tin-based Babbitt) cast in bronze or steel housing
successor_series: None
Common Failures:
- • White metal wiping from shaft misalignment or sudden load
- • Oil contamination from seawater ingress past stern tube seal
- • Oil loss to sea from seal failure — MARPOL environmental concern
- • Bearing temperature rise from oil degradation
Service: Stern tube oil level/quality check daily. Oil temperature monitoring continuous. Oil analysis every 3 months. Bearing clearance measurement at drydock. White metal re-casting if wiped — specialized shore facility.
Spares: Multiple manufacturers (Aegir Marine Netherlands, Blohm+Voss Germany, local foundries). White metal re-pour: 1-3 weeks at specialized facility. Emergency repair at drydock.
Duramax DM Marine Bearing
Per propulsion shaft design
· Seawater-lubricated
Common Failures:
- • Stave wear
- • Edge loading from misalignment
- • Foreign object damage
Service: Composite stave bearing; environmentally friendly; long service life.
Spares: Duramax: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
Duramax Marine / Wärtsilä (USA/Finland) Johnson Cutless Bearing
Shaft diameter 25-750 mm
· Seawater lubricated
type: Water-Lubricated Stern Tube / Strut Bearing (Rubber)
size_range: ['Cutless 400', 'Cutless 500', 'Cutless 700 HP']
power_range_kw: None
variant_count_approx: 3
period_start_year: 1940
period_end_year: None
drive_type: Passive (seawater lubricated)
construction: Nitrile rubber staves in bronze or non-metallic shell
successor_series: None
Common Failures:
- • Rubber stave wear from sand/debris ingestion
- • Rubber delamination from age/UV exposure (above waterline bearings)
- • Shell corrosion (bronze — dezincification in stagnant seawater)
Service: Bearing clearance measurement at drydock. Typical life 5-15 years depending on operating conditions. Replacement at drydock when clearance exceeds Class limits.
Spares: Duramax Marine (Cleveland, OH, now part of Wärtsilä). Standard sizes widely stocked. Lead time: 1-3 weeks for standard, 4-8 weeks for custom sizes.
Kamome Propeller (Japan) KP Stern Tube System
Shaft diameter 150-700 mm
· Oil lubricated
type: Complete Stern Tube System (Bearing + Seal + Oil System)
size_range: ['KP-150', 'KP-300', 'KP-500', 'KP-700']
power_range_kw: None
variant_count_approx: 4
period_start_year: 1970
period_end_year: None
drive_type: Passive (oil lubricated)
construction: White metal bearing, lip seal, gravity oil tank
successor_series: None
Common Failures:
- • White metal wiping from alignment issues
- • Seal wear causing oil loss
- • Oil tank level drop from seal leakage
Service: Stern tube oil level check daily. Oil analysis quarterly. Bearing clearance at drydock. Seal replacement at drydock.
Spares: Kamome Propeller (Aioi, Japan). Lead time: 3-5 weeks Asia.
Kobelco Eagle Marine (Japan) KE Stern Tube Seal
Shaft diameter 150-800 mm
· Seawater / Stern Tube Oil interface
type: Stern Tube Seal (Lip Seal)
size_range: ['KE-150', 'KE-300', 'KE-500', 'KE-800']
power_range_kw: None
variant_count_approx: 4
period_start_year: 1975
period_end_year: None
drive_type: Passive
construction: Multi-lip rubber seal, chrome or ceramic shaft liner
successor_series: None
Common Failures:
- • Lip seal wear from shaft liner surface deterioration
- • Oil consumption increase from worn aft seal
- • Ceramic liner chipping (ceramic variants)
Service: Drain inspection daily. Seal replacement at drydock. Shaft liner inspection at seal change.
Spares: Kobelco Eagle Marine (Kobe, Japan). Lead time: 3-5 weeks Asia, 6-10 weeks elsewhere.
Kongsberg Maritime AS Avd Skonnertvegen Bearing Wear Sensor PSS11
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: Kongsberg Maritime AS Avd Skonnertvegen: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
Micromatic (Italy) MM Stern Tube Bearing
Shaft diameter 100-800 mm
· Oil lubricated / Water lubricated
type: Stern Tube Bearing (White Metal / Polymer)
size_range: ['MM-100', 'MM-300', 'MM-500', 'MM-800']
power_range_kw: None
variant_count_approx: 4
period_start_year: 1985
period_end_year: None
drive_type: Passive
construction: White metal or polymer in bronze housing
successor_series: None
Common Failures:
- • White metal wiping from misalignment
- • Polymer wear from debris ingestion (water-lubricated)
- • Housing fit loosening from vibration
Service: Per bearing type. Oil-lubricated: oil analysis quarterly. Water-lubricated: clearance check at drydock.
Spares: Micromatic (Genova, Italy). Lead time: 4-6 weeks.
Orkot / Trelleborg (UK/Sweden) TLM Marine Bearing
Shaft diameter 50-1,000 mm
· Water lubricated / Oil lubricated
type: Composite Polymer Stern Tube Bearing
size_range: ['Orkot TLM', 'Orkot TXMM', 'Orkot C301']
power_range_kw: None
variant_count_approx: 3
period_start_year: 1990
period_end_year: None
drive_type: Passive
construction: PTFE/polyester composite, self-lubricating
successor_series: None
Common Failures:
- • Wear from contaminated lubrication water
- • Swelling from incompatible lubricant contact
- • Edge loading from shaft misalignment
Service: Clearance check at drydock. Self-lubricating — less maintenance than white metal. Typical life 10-20 years. No oil pollution risk.
Spares: Trelleborg Sealing Solutions (Rotherham, UK). Lead time: 3-6 weeks for standard sizes, 6-10 weeks for custom.
SKF Marine (Sweden) Simplex Compact Seal
Shaft diameter 100-1,200 mm
· Seawater / Stern Tube Oil interface
type: Stern Tube Seal (Lip Seal)
size_range: ['Simplex Compact S', 'Simplex Compact M', 'Simplex Compact L', 'Simplex Compact XL']
power_range_kw: None
variant_count_approx: 4
period_start_year: 1950
period_end_year: None
drive_type: Passive
construction: Multi-lip rubber seal, chrome liner, spring-loaded
successor_series: None
Common Failures:
- • Lip seal wear from shaft liner scoring
- • Chrome liner pitting from seawater corrosion
- • Seal housing bolt corrosion/seizure
- • Oil loss from worn aft seal
Service: Same as Wärtsilä seals. Drain inspection daily. Seal replacement at drydock. Chrome liner reconditioning or replacement if scored. Oil analysis every 3 months.
Spares: SKF Marine (Gothenburg, Sweden). Simplex seal kits: 3-6 weeks. Chrome liners: 6-10 weeks.
SKF Marine GmbH Bulkhead seals, split and not split version and its design
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH CENTRAX, CENTRAX-FC, CENTRAX-FG, CENTRAX-FB, Option: -A (adapter ring)
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH Models: Turbulo Mechanical Phase Breaker (TMPB) 0.25, 0.50, 1.0, 2.5, 5.0, 7.5, 10.0, 15 ppm Separator
Per propulsion shaft design
· Propulsion Shaft Line
source: uscg-cgmix
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH SIMPLAN-C, SIMPLAN-C-P, SIMPLAN-SiC, SIMPLAN-SiC-P
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH SIMPLAN-SC (combination of SIMPLAN axial and SIMPLEX radial)
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH Simplex-Compact SC3 Pod seals
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH Simplex-Compact Stern Tube Seals, Types SC2 and SC3
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH Simplex Stern Tube Bushes
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH TMPB 0.25, 0.5, 1, 2.5, 5, 10, TMPB 0.25/A, 0.5/A, 1/A, 2.5/A, 5/A, 10/A, TMPB 0.251/A, 0.51/A, 1.01/A
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH TPW-S, TPW-L
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
SKF Marine GmbH Tunnel Bearings and Plummer Blocks
Per propulsion shaft design
· Propulsion Shaft Line
source: dnv-approval-finder
Common Failures:
- • Wellenlager-Verschleiß bei Küsten-/Flachwasser-Betrieb (Sand/Schlick)
- • Wellenabdichtung-Leckage verursacht Ölverlust ins Meer
- • Propellerflügel-Kavitationserosion
- • Wellenfluchtungs-Abweichung verursacht ungleichmäßigen Lagerverschleiß
Service: Lagerspiel-Messung bei Dockung. Wellenabdichtung tägliche Drain-Inspektion. Ölanalyse quartalsweise. Propeller-Inspektion bei Dockung.
Spares: SKF Marine GmbH: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
Thordon SXL Bearing
Per propulsion shaft design
· Seawater-lubricated
· Water-lubricated polymer
Common Failures:
- • Bearing wear beyond class limit
- • Scoring from debris
- • Misalignment wear pattern
Service: Water-lubricated polymer bearing; no oil pollution risk; measure wear at drydock.
Spares: Thordon: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.
✔ Pros
- • Eliminates oil pollution risk
- • Reduced maintenance due to water-lubrication
- • Compliant with environmental regulations
- • Increased durability and resistance to wear
- • Easy to measure wear during drydock
⚠ Cons
- • Bearing wear beyond class limit can occur
- • Scoring from debris is a potential issue
- • Misalignment wear pattern can be a problem
- • May require more frequent inspections
- • Higher upfront cost compared to traditional bearings
Typical Vessels:
ContainerBulk CarrierTankerCruise ShipFerry
Certifications:
IMODNVABS
Decision Guide: Choose if you prioritize environmental compliance and reduced maintenance. Avoid if you are looking for a low upfront cost solution or have limited experience with water-lubricated bearings.
Use Cases: Typically deployed in commercial vessels that require a reliable and environmentally friendly propulsion system, such as those operating in sensitive marine ecosystems or under strict environmental regulations.
Thordon Bearings (Canada) SXL / COMPAC Series
Shaft diameter 100-1,000 mm
· Seawater lubricated
type: Water-Lubricated Stern Tube Bearing (Polymer)
size_range: ['SXL 150', 'SXL 300', 'SXL 500', 'SXL 700', 'COMPAC 150', 'COMPAC 500']
power_range_kw: None
variant_count_approx: 6
period_start_year: 1985
period_end_year: None
drive_type: Passive (seawater lubricated)
construction: Elastomeric polymer staves in bronze/steel housing
successor_series: None
Common Failures:
- • Bearing wear from sand/silt ingestion in shallow/coastal waters
- • Uneven wear from shaft misalignment
- • Stave debonding from housing in extreme conditions
- • Noise/vibration from stick-slip at low speeds
Service: Bearing clearance measurement at drydock (poker gauge). Wear rate monitoring — typical life 15-25 years on deep-sea vessels, shorter on coastal. Shaft alignment check at each drydock. No oil pollution risk — environmentally compliant (VGP/EPA).
Spares: Thordon Bearings (Burlington, Ontario, Canada). Replacement staves: 4-8 weeks. Emergency service: Thordon has 24/7 global support. Keep onboard: wear measurement tools.
Vesconite (South Africa) Vesconite Hilube Marine
Shaft diameter 25-500 mm
· Water lubricated / Dry running capable
type: Thermoplastic Polymer Bearing (Marine Grade)
size_range: ['Vesconite 25-100', 'Vesconite 100-250', 'Vesconite 250-500']
power_range_kw: None
variant_count_approx: 3
period_start_year: 1990
period_end_year: None
drive_type: Passive
construction: Proprietary thermoplastic polymer, machinable, self-lubricating
successor_series: None
Common Failures:
- • Thermal expansion at high operating temperatures
- • Surface scratching from debris ingestion
- • Dimensional instability in fluctuating temperature environments
Service: Clearance check at drydock. Self-lubricating — minimal maintenance. Can run dry temporarily. Suitable for rudder, stern tube, and deck machinery bearings.
Spares: Vesconite Bearings (Virginia, South Africa). Global distribution. Lead time: 1-3 weeks for standard sizes. Machinable from bar stock — emergency fabrication possible onboard.
Wartsila Seals & Bearings / Cedervall (Finland/Sweden) Wartsila Stern Tube Seal (Lip Seal)
Shaft diameter 150-1,200 mm
· Seawater / Stern Tube Oil interface
type: Stern Tube Seal (Lip Seal / Face Seal)
size_range: ['Airguard', 'Enviroguard', 'FSTL', 'FST']
power_range_kw: None
variant_count_approx: 4
period_start_year: 1960
period_end_year: None
drive_type: Passive
construction: Multi-lip rubber seal rings with air/oil barrier
successor_series: None
Common Failures:
- • Lip seal wear from shaft roughness/scoring — primary oil loss cause
- • Seal ring hardening from age (rubber degradation after 10-15 years)
- • Shaft liner scoring from debris trapped under seal lips
- • Air supply system failure on Airguard models causing oil loss
Service: Seal drain inspection daily. Air supply pressure check daily (Airguard). Oil consumption monitoring — abnormal increase indicates seal wear. Seal replacement at drydock (every 5-10 years or as needed). Shaft liner condition check at each seal replacement.
Spares: Wärtsilä Seals & Bearings (ehem. Cedervall, Gothenburg). Seal kits: 4-8 weeks lead time. Keep onboard: spare seal elements for emergency replacement afloat (limited repair possible).
Wärtsilä Oil-Lubricated White Metal
Per propulsion shaft design
· Lube Oil
Common Failures:
- • White metal fatigue cracking
- • Oil starvation damage
- • Temperature alarm
- • Wiping
Service: Traditional white metal; monitor bearing temperature continuously.
Spares: Wärtsilä: Dichtungs-Elemente und Verschleißmesswerkzeuge an Bord vorhalten. Lead time: 4-8 Wochen.