Challenges and Progress in Meeting a US Navy Fleet Need: Effective Underwater Hull Coatings

for Biofouling Control

Elizabeth Haslbeck*, Eric Holm, and Kody Lieberman Naval Surface Warfare Center, Carderock Division

Code 613 - Coatings and Corrosion Control Research and Development Branch Bethesda, Maryland 20817-5700 USA

*elizabeth.haslbeck@navy.mil

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Outline

•  History of antifouling coating technology (US Navy) •  US Navy-unique constraints, drivers, and considerations •  Performance specification – coating qualification for use

in US Navy Fleet •  Current efforts

–  Advanced coatings –  Cleaning technologies/approaches –  Challenges, directions

•  Summary and acknowledgements

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US Navy - Biofouling Control Evolution 1910’s

•  Commercial off-the-shelf (COTS) coating systems •  Thick, solvent-based varnishes or shellacs •  Service life ~ 6-9 months at best •  Drydocking interval – 1 year

1920’s

•  Switched to US Navy formulations •  Rosin-coal tar paints •  Service life 9 months •  Replace at each annual drydocking

1940’s •  Continue - US Navy formulations •  Hot thermoplastics; heat to 149oC for application (300oF) •  Significant cracking/checking •  Service life 2 years – replace each drydocking

1950’s and 1960’s •  Continue - US Navy formulations •  Vinyl binders – thin-bodied, sprayable, fast-drying •  Service life ~ 2 years, but can retain/touch up in drydock

1920 1940

1960

From: W. J. Francis, Journal of the American Society of Naval Engineers, 66:857-867 (1954) 3 From: CAPT H. Williams, Journal of the American Society of Naval Engineers, Vol. 35 (1923)

Cu, H

g, A

s, Zn C

u, Hg

Cu

US Navy - Biofouling Control Evolution 1970’s

•  US Navy formulation - Formula 121 (F-121) ‒  Service life up to 18 months ‒  Paired with in-water cleanings to

realize 3-5 year service

1980’s •  Changeover to COTS technology

‒  Copper ablatives §  Biocide: cuprous oxide §  Continued in-water cleaning to realize

5-7 year service life

‒  Self-polishing copolymers (SPCs) + TBT §  US Navy used experimentally

•  Technology transition via Military Performance Specification

(MIL-PRF-24647, 1986)

1920 1940

1960 1980

2000+

Image: McClatchy Washington Bureau

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US Navy - Biofouling Control Evolution

1990’s and 2000’s •  Continued the use of copper ablatives

‒  Currently installed on more than 95% of Fleet ‒  Designed with 3-5 year service life ‒  Continued reliance on in-water cleaning ‒  Further extension of interval between

drydocking: 8-10, up to 12 years §  Apply 3 topcoats of antifouling

•  Search for new technologies continues … ‒  COTS technologies ‒  Meet unique US Navy needs

1920 1940

1960 1980

2000+

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Constraints: Commercial vs. Navy Important differences: •  Interval between drydocking •  Inspection/cleaning program •  Operations

–  Operational tempo and speed/time profile

•  Number of ships –  Coatings formulated for commercial vessels aren’t

designed for unique needs of US Navy

6

0

10

20

30

40

50

60

70

80

Percent Time

(Annual)

<10 11 13 15 17 19 21 23 25+

Speed (knots)

DDG FFG Containership

Considerations When Evaluating New Technology Interdependent Variables

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Ship activity/inactivity

The US Navy’s underwater biofouling control technology evaluation process has many interacting parts.

Characterizing performance, service life, costs and benefits is challenging

Considerations & Constraints

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The Navy’s options for improving the underwater biofouling control process are influenced by parameters which we cannot control

Con

stra

ints

Performance Specification - MIL-PRF-24647E (http://www.nstcenter.biz)

•  Defines process for qualifying hull coating systems for US Navy use (6 sections)

•  Section 1 – coatings are qualified by: ‒  Types I-IV (chemistry/mechanism) ‒  Class 1-3 (substrate – rigid/steel, aluminum, elastomeric) ‒  Grade A-C (volatile organic compound [VOC] content) ‒  Application 1-4 (service life)

§  3 years or less §  7 years or less §  12 years or less §  High speed vessels for minimum of 2 years

•  Section 2 – documents/references –  Federal standards –  Department of Defense standards –  Code of Federal Regulations documents –  Non-government publications and standards

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Type Class App 1 App 2 App 3 App 41 YES YES YES YES

I 2 YES YES YES YES3 YES YES YES NO1 YES YES YES YES

II 2 NO NO NO NO3 YES YES YES NO1 YES YES NO YES

III 2 YES YES NO YES3 YES YES NO NO1 YES YES NO NO

IIIa 2 YES YES NO NO3 YES YES NO NO1 YES NO NO NO

IV 2 YES NO NO NO3 YES NO NO NO

Performance Specification - MIL-PRF-24647E (http://www.nstcenter.biz)

•  A “type” category may need to be developed for coatings and/or coating-like technologies not listed here.

•  For non-coating technologies, a new specification may be needed

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Performance Specification - MIL-PRF-24647E (http://www.nstcenter.biz)

•  Section 3 – Requirements – extensive qualitative and quantitative evaluation properties/parameters (defines metrics) ‒  Performance metrics

§  Panel tests §  Ship tests

‒  System identification & composition ‒  Storage, mixing, application

•  Section 4 – Verification ‒  Identifies tests ‒  Defines protocols

•  Sections 5 & 6 – Notes and intended use, acquisition requirements, safety/technical data, shelf-life, packaging

Panel test

Production, application/cure

properties

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Full-scale test

US Navy Current Efforts

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Improved biofouling control most likely will be a function of: Advanced biofouling control coatings:

•  Evaluate relative to legacy coatings - plus - Alternative cleaning technologies/strategies:

•  Evaluate relative to legacy cleaning approaches

Goals: •  More reliably steam with less biofouling – hulls and propellers •  Reduce reliance on in-water inspection and cleaning overall •  Delay “first cleaning” •  Adequately navigate the long list of constraints

‒  Environmental ‒  Material compatibility ‒  Interval between drydockings ‒  Operational profile ‒  Etc.

•  Longer coating “effective service life”

US Navy – Current Efforts Advanced Coatings

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•  Antifouling (AF) –  Acrylates (silyl, zinc, copper, hybrid, etc.)

§  Copper-free §  Cuprous oxide plus booster

–  Copper-free ablative

•  Foul-release (FR) – silicone, fluoropolymer, hydrogel, lubricated outer layer, oil-filled

•  AF/FR – foul-release plus biocide

US Navy – Current Efforts Advanced Coatings - Evaluation

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•  Method appropriate for mechanism

–  Antifouling –  Foul-release

•  Goal: screening tests well-predict performance full scale

•  Adapt existing or develop new methods as new technologies are introduced

US Navy – Current Efforts Advanced Coatings - Evaluation

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•  Full-scale testing – required full hull and patch –  Commercial – 2 year test –  Navy/military – 1 year test

US Navy – Current Efforts Advanced Coatings – Evaluation

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•  Data collection – full scale tests ‒  Fouling and physical performance evaluation

§  Divers §  Remotely operated vehicles

‒  Inspection/cleaning history ‒  Ship activity/inactivity

•  Fuel efficiency metrics •  Business case development to justify transition http://seatrepid.com/products/videoray-rov/

More rigorous requirements for collection of data from ships full scale are being considered – performance specification MIL-PRF=24647.

US Navy – Current Efforts Cleaning Technology

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•  Rotating brush tools •  Non-contact cleaning tools (waterjet)

Cleaning GOALS: •  Ensure fouling-free, at-sea operations •  Preserve coating (physical) •  Low impact on coating system •  Low impact on environment •  Effective underpinning of coating system

US Navy – Current Efforts Cleaning

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•  We need an improved understanding of how cleaning tools impact coatings

•  No matter the coating type – current and future – given the US Navy’s unique parameters (long intervals between drydocking, and operational profile), at some point cleanings will be needed

•  We have evaluated impact of cleaning tools using –  Panels –  Ships – full scale

A standard screening method may be useful.

US Navy – Current Efforts Other Cleaning Considerations …

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•  Change timing of cleaning relative to ship activity? •  Change threshold for cleaning?

–  Fouling rating? –  Coverage?

•  Change the fouling rating? –  Better align with hydrodynamic penalty? –  Unanticipated consequences?

•  Change tool? –  Rotating brush? Waterjet? –  Standoff, translation rate, residence time?

•  Change approach? –  Reactive –  Proactive

Hypothetical data

•  Cost vs. benefit? •  Impact on coating service life? •  Environmental inputs?

US Navy – Current Efforts Advanced Coatings – Evaluation

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•  Improved performance ‒  Goal: proportionally more time spent at sea without fouling intact

§  Without cleaning vs with cleaning ‒  Longer time to first cleaning ‒  Fewer cleanings ‒  Coating performs well physically between drydockings

US Navy – Current Efforts Advanced Coatings – Evaluation

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•  Improved performance ‒  Goal: proportionally more time spent at sea without fouling intact

§  Without cleaning vs §  With cleaning

‒  Longer time to first cleaning ‒  Fewer cleanings ‒  Coating performs well physically between drydockings ‒  Should the performance specification expand testing and requirements?

Balance cost and risk …

Summary

•  More reliably steam with less biofouling – hulls and propellers •  Reduce reliance on in-water inspection and cleaning overall •  Delay “first cleaning” •  Adequately navigate the long list of constraints

‒  Environmental ‒  Material compatibility ‒  Interval between drydockings ‒  Operational profile ‒  Etc.

•  Longer coating “effective service life” All while balancing cost and risk

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Needs •  Materials

–  Coatings that delay onset of fouling (during lengthy pierside intervals) –  Alternatives to coatings?

•  Maintenance –  Proactive grooming? Need business case –  Cleaning tool impact characterization

•  Monitoring –  Improved panel/screening tests; better prediction of full-scale performance –  Improved understanding of coating performance across various combinations of

static and dynamic intervals –  Fuel efficiency metrics

§  Modeling of roughness impact on fuel efficiency (e.g. from hull inspections) §  Impacts of heterogeneous mixtures of roughness

•  Movement –  Co-location of existing data streams for “data mining” and development of decision

matrices

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Acknowledgements

•  Naval Surface Warfare Center (NSWC) Biofouling Team

–  Coatings and Biofouling – Eric Holm, Kody Lieberman, Dave Stamper, Angela Ross –  Hull inspection – Crystal Lutkenhouse, Keith Schlee –  Hydrodynamics and modeling – Thad Michael, Carol Tseng, Abel Vargas, Peter Cheng, Dominic Cusanelli,

Doug Griggs, Eric Giesberg –  Grooming – Mr. Matt Naimen, Mr. Bill Hertel

•  … and, by extension, a wide array of universities, institutes, and industrial partners …

•  Sponsors –  Naval Sea Systems Command (NAVSEA) PMS407 (Mr. Viet Nguyen and Mr. Montrell Smith) –  Military Sealift Command Energy Conservation Program (Mr. Sonjae Whang) –  NSWCCD NISE/219 (Dr. Jack Price) ‒  Office of Naval Research Code 331 (Dr. Paul Armistead)

‒  NAVSEA 05T1 (Mr. Tom Martin, Mr. Mike Essig, Mr. Kellen Bucher) ‒  OPNAV N455 (Capt. Feinberg)

•  NAVSEA stakeholder input –  NAVSEA 05P2 (Mr. Mark Ingle) – coatings and corrosion control –  NAVSEA 05P5 (Ms. Holly Nestle) - environment –  NAVSEA 05T1 (Mr. Tom Martin/Mike Essig) - energy –  NAVSEA 00C5 (Mr. Tom McCue) – maintenance –  NAVSEA 05Z (Mr. Jeff Schumann) – propellers

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