Eliminating discharges in

oil/sea interfacesSeawater lubricated propeller shaft systems for

commercial ships

Presented by

Craig Carter, Thordon Bearings

Ship Efficiency: The Event 9 September 2015

Overview

• Problems with oil/sea interfaces in

propeller shaft lines

Operational Discharges

Accidental Discharges

• Regulations impacting ship owners US EPA – Vessel General Permit

Polar Code

• Options for Ship Owners

Air Seals / oil-based EAL’s

Seawater lubricated propeller shaft lines2

3

Propeller Shafts

Lubricated With Oil• Typical stern tube system has 1500 to 3000

litres of mineral oil

OIL

Oil to seainterface

Oil Lubricated Propeller Shafts

Tailshaft and pod seals do not operate in a perfect environment

• Pollution risk Seal must leak to lubricate its sealing lip

Oil pollution from leaking shaft or pod seal• Rope and fishing line damage seals

Escalating detection and enforcement

• MARPOL Annex I

• Satellite tracking

• Criminal fines

• Jail terms

Increased expectation of corporate

responsibility

• Damage to corporate brand and image

4

Oil discharges from commercial ships… a

serious problem

• Approximately 95% of commercial ships use oil lubricated metal propeller shaft

bearings.1

• Environmental Research Consulting (New York) study

“Total annual inputs of lubricating oil worldwide from stern tube leakage and other

operational discharges into port waters is estimated to be between 37 million to nearly 61

million litres. If the same rates of discharge occur at sea as they do in port, the estimated

worldwide annual inputs of lubricants to marine waters both in ports and harbours and at sea

might be estimated to be about four times the port estimate.

Total worldwide use of lubricants from operational leaks and discharges would then

be about 130 million to 244 million litres annually.2

51 Data related to Propulsion systems, IHS Fairplay database

2 Etkin, Dagmar Schmidt. Environmental Research Consulting “Worldwide Analysis of In-Port Vessel Operational

Lubricant ,” Arctic and Marine Oilspill Program Seminar of Environment Canada, 8 June 2010, Halifax, Canada

DNV Report – Operational Oil

Discharges Not Effectively Regulated

6

• Prepared for Norwegian Maritime Directoratefor consideration of Development of a Mandatory Code for Ships Operating in Polar Waters

• Discharges from shipping during regular operation in polar areas

• Presented at IMO DE 54 (Aug. 2010)

As a potentially relative large source of operational oil discharge, however still not effectively regulated and of unknown exact magnitude, stern tube leakage should be addressed as a particular environmental aspect in the polar environment as well as in other areas. Of particular importance under ice operation is the potential for especially high leakage rates, and the proximity to ice with regards to deposition of oil.

7

Accidental Oil Leakage

• Typical causes of increased oil leakage from stern tube

seal damage:

Fishing nets or rope caught in the propeller

Propeller shaft misalignment or bent shafts

Aged or worn lip seals

Propeller contact

with ice or striking bottom

Accidental Oil Leakage

8

Rope and fishing line damage aft seals.

Lloyd’s Register reports on shaftline defect

statistics over the last 20 years: “interestingly,

aft stern seal and forward stern seal represent

43% and 24% of shaftline failures respectively.”

3 Smith, Andrew, Lloyd’s Register Global Technology Leader-Engineering Systems .,

“Shaft Alignment Problems Analyzed,” Marine Engineers Review April 2009, pp. 16

9

Accidental Oil Leakage

• CleanSeaNet… Using satellite

imagery to detect oil spills-Apr. 2007

to Dec 2008 in European oceans/

seas.

“4,027 possible oil slicks were detected and reported to the authorities. The percentage of CleanSeaNet detections checked on site by aircraft or vessels confirmed as being mineral oil may vary from one region to the other but can reach values as high as 80%

Marc Journal, European Maritime Safety Agency Bulletin 2009 CleanSeaNet: Satellite-based monitoring service for marine oil spill detection and surveillance in European waters, pp 48-51

10

Oil Slick Detections

via Satellite: 2008

European Maritime Safety Agency Bulletin 2009 CleanSeaNet: Satellite-based monitoring service for marine oil spill detection and surveillance in European waters, pp 48-51

Accidental Oil Leakage

Reported in the PressSeals repaired due to oil discharges (since 2009)

11

Trading in US Waters?

• 2013 Vessel General Permit (VGP) regulates

discharges from commercial vessels in ‘US

waters’ effective Dec. 19, 2013

• Section 2.2.9: All vessels must use an EAL

“Environmentally acceptable lubricant” in all oil to

sea interfaces, unless technically infeasible

• EPA recommends that all new build vessel

operators endeavor to use seawater-based

systems for their stern tube lubrication to

eliminate the discharge of oil from these

interfaces to the aquatic environment.12 http://www.epa.gov/npdes/vessels

New Polar Code

• Development of a Polar Code for ships operating in polar waters

• Polar waters will be “zero discharge” areas under MARPOL Annexes 1

and 2 (oil and noxious liquids).

• The Code states: “Any discharge into the sea of oil or oily mixtures

from any ship shall be prohibited.”

• Polar Code enters into force:

January 1, 2017

13

Complex Shaft Air Seals

Are they the answer?• A major seal manufacturer states the following related to air seals

on their website:

However, since it is not possible to rule out circumstances in which

there could be a leakage, EALs must be used on this type of seal as well.

• Depending on seal manufacturer and EAL, the EAL will need to

be replaced either at 2.5 or 5 year drydocking (aggressive nature

of the EAL on seals)

14

http://www.simplexturbulo.com/2013/07/12/vessel-general-permit-latest-news/

Typical Piping of Air Seal

15

Air control unitAir source

(Control Air)

L.O. tank unit

Floatswitch

Stern tube

Stern tubeL.O. pump unit

Filter

Pump

Draincollection unit

Flow meter

Air

Oil

Slight amount of air

is leaked from here.

Aft seal

Cooler

Needle valve

Oil and vegetable-based EAL’s…

Still considered a pollutant Oil-based EAL’s are still considered a pollutant under the

Oil Pollution Act of 1990 (OPA ‘90) and US Clean Water

Act (if there is a sheen)

Any discharges of oil-based EAL’s still require reporting

of the discharge to the U.S. Coast Guard, as well as

having clean-up and remediation costs, if required.

Even though biodegradable lubricants may be deemed

non-toxic by OECD testing, their presence on the water

surface is a threat to seabirds

16

Stern Tube Lubricants

17

Seawater Lubrication

• Seawater as a lubricant dates back to

earliest days of shaft driven propellers

• Today’s seawater lubricated propeller shaft

lines quite different than those of 1940’s

18

19

Today’s Seawater Lubricated

Propeller Shaft Bearing System

Elastomeric

Polymer Alloy Bearings

• Toughness, abrasion resistance, shock loading

• Typically, 2:1 L/D ratio for AFT bearing and 1:1

L/D ratio for FWD position

20

21

Water Quality Package

• Designed to provide a clean supply of

water to the water lubricated bearings

Controlled environment

• Flow is monitored and low flow alarms provided

Removes abrasives

Improves bearing wear life

Self contained unit

Piping for Seawater Lubricated Propeller Shaft Bearing

System

22

NO AFT SEAL!

New Lloyd’s Register Rules

for Water Lubricated

Propeller Shaft Bearings

• New SCM (Screwshaft Conditioning

Monitoring) Notation

For water lubricated propeller shaft bearings

Effective Jan. 2013

• If vessel is compliant, no shaft

withdrawal until 18 years from newbuild

23

New Bureau Veritas Rules

for Water Lubricated

Propeller Shaft Bearings

• Revised MON-SHAFT Notation

For water (and oil) lubricated propeller shaft

bearings

Effective Jan. 1, 2014

• The tailshaft need not be withdrawn

provided that all condition monitoring

data are found to be within the

permissible limits and remaining

surveys are complied with 24

Who Uses Seawater Lubricated Propeller

Shaft Bearings?

Over 600 commercial ships including…• COSCO (China) - 12 bulk carriers, 3 car carriers, 20 On order

• ConocoPhillips (U.S.A.)- 5 oil tankers

• Flinter Group (Netherlands) – 24 dry cargo ships

• Disney Cruise Lines (U.S.A.) – 4 cruise ships

• BC Ferries (Canada) - 10 ferries

• Carisbrooke Shipping (U.K.) - 8 dry cargo ships

• CSL (Canada) - 9 bulk carriers

• Staten Island Ferries (U.S.A) - 3 ferries

25

26

Carnival Corp. (U.S.A.) – 17 Cruise ships (108,000 to

115,000grt) equipped with seawater lubricated propeller

shaft lines. Two more on order.

Grand Princess has used seawater lubricated propeller shaft lines since 1998

Long Predictable Bearing Wear Life

Lower Life Cycle Costs

27

Newbuild Aframax tanker (640mm shaft diameter)

25 year vessel life

Life Cycle Cost Analysis

Seawater Lubricated

COMPAC Propeller

Shaft Bearing System

Oil Lubricated White

Metal Prop Shaft

Bearing System

Bearings, shaft liners, seal(s)

and related shaft line equipment $286,750 $193,500

Cost of Acquisition & Installation $286,750 $193,500

Cost of Ownership (25 Years) $134,000 $535,840

TOTAL $420,750 $729,340

Operational & Performance

Benefits• Zero Pollution Risk

Eliminate oil from the stern tube

• Controlled Bearing Environment

Water Quality Package

Allows for SCM & T-MON Notation– No shaft

withdrawal for 18 years with monitoring

• Technical equivalence

Viable alternative to oil lubricated white metal

propeller shaft bearings

28

Operational & Performance

Benefits

• Reduced Operating Costs• No Aft seal to maintain as there is no Aft seal

(water lubricated FWD seal only)

• Eliminate oil or oil-based EAL’s from the stern

tube

no purchase of oil; no storage of oil

no sampling of oil; no disposal of oil

no labour required to top up header tanks

no complaints about bad odour

• Maintenance of seawater lubricated propeller

shaft bearing system is very low

29

The Future

• Environmental compliance for a ship owner is a constantly

moving line and it is not going backwards.

• A seawater lubricated propeller shaft bearing system is

the only system that guarantees compliance and has

ZERO impact on environment.

30