N131-022 TITLE: Craft Hull Impact and Abrasion Resistance

TECHNOLOGY AREAS: Materials/Processes

ACQUISITION PROGRAM: PMS 325G, Small Boast and Craft Program Office

OBJECTIVE: Development of an innovative material solution and applicable manufacturing techniques to provide improved protection for aluminum and composite USN small craft hulls against excessive abrasion and impact damage.

DESCRIPTION: Naval expeditionary patrol, interdiction, and assault craft experience hull impacts and abrasion in the performance of common operational tactics and procedures. The hulls (Ref 1) are subjected to abrasion due to beaching and grounding, and suffer impact damage to various areas above and below the waterline during launch, recovery, interceptions of rouge craft, landings at un-improved sites and marine structures as well as from un-intentional contact with objects at or below the water�s surface. The current abrasion or impact resistance solution for aluminum hulls is the application of add-on rubberized rub-rail materials, the use of a hull collar or the inclusion of a sacrificial aluminum doubler-plate on the bow keel. Rub-rail and collar materials require mechanical fasteners and hull penetrations and can enable corrosion at points of contact with the aluminum hull, often failing at the point of mechanical attachment and requiring maintenance of the surfaces to which they mate. The aluminum doubler-plates installed on in-service craft wear through requiring repair or replacement which is costly and requires the use of specialized personnel. Additionally, fabrication and welding are difficult and time consuming due to the complex shape and awkward position of the plate on the hull. Repair of the bow plate alone costs approximately $10K and requires 10 or more days out of service, not including the transportation time to a depot level maintenance facility and any work delays. During these types of repairs, the craft is not available as a mission ready asset. Similar costs and times to repair are estimated for other areas of the hull where harmful impacts occur and a repair is required. Composite boats have similar life cycle challenges. Two methods are currently employed to provide protection to the composite bow keel, a laminate in place or an add-on solution. Craft have been delivered with added protection laminated into the original mold and have also been modified with a shop built, laminated cut-water part attached with adhesive and a vacuum bag to clamp the part in place (Ref 2). As with the doubler-plate on aluminum craft, this solution experiences similar performance challenges in expeditionary environments. These highly integrated types of solutions are costly and labor intensive to install and both the �in place� and �add on� options pose challenges to in-place repair. For both aluminum and composite hulls, the currently used commercially available solutions are considered the "state of the art". Future technology solutions in areas such as, but not limited to, polymer science, nano-structure materials, bonding materials science, etc. could be viable; however, performance and suitability for use in the strenuous operating environment discussed in this topic vice recreational boating applications have not been demonstrated nor proven.

This topic seeks to develop innovative material solutions and applicable manufacturing techniques that can be implemented to provide improved hull-form abrasion and impact resistance for a seven year craft service life with only minor field-repairs, such as filling of gouges or smoothing of roughened surfaces. Concepts proposed should not alter or propose alternate standard base hull materials nor require installation via mechanical fasteners or through-hull penetration. Concepts must be able to conform to various hull shapes and surfaces (bow keel/fenders, transom corners, keel guards, strakes) and should not serve as a catalyst for corrosion. Concepts should be easily repairable (not requiring specialized skills such as metallurgical welding, specialized composite materials mixing, etc), easily replaceable if damaged beyond repair and should be implementable with minimal manpower, simple tools and little to no training. Proposed material solutions and repair methodologies must not degrade craft performance due to excessive weight or flow resistance. Proposed concepts must also demonstrate more durable protection and higher strength than 5086-H116 aluminum, or the Navy composite solutions. Proposed concepts will be compared and evaluated for suitability using ASTM International abrasion and bond-strength tests, Det Norske Veritas (DNV) drop impact test (Ref 3), as well as any other relevant industry test proposed by the candidate to measure impact or abrasion that would aid in the identification of a superior material solution (Ref 4). Achieving this topic�s goals would directly increase mission readiness by: shortening down-time due to repair or replacement; increase mission capability in that the hull will be able to endure the regular beaching and impacts; reduce life cycle costs by providing a more durable and cost effective solution that can be easily repaired and replaced if necessary without the assistance of depot maintenance facilities and specialized skill-sets.

PHASE I: The company will develop an innovative material concept and any applicable manufacturing techniques that improve protection for aluminum and composite expeditionary and combatant craft hulls against excessive abrasion and loss of hull material. The company will demonstrate the feasibility of the concepts in meeting the Navy needs and will establish that the concepts can be feasibly developed into a useful product for the Navy. Feasibility will be established by material testing and analytical modeling. The small business will provide a Phase II development plan with performance goals and key technical milestones while addressing technical risk reduction.

PHASE II: Based on the results of Phase I and the Phase II development plan, the small business will develop a scaled prototype of a bow keel and shell plate region to represent key impact zones for evaluation in a laboratory environment, as appropriate. The prototype will be evaluated to determine its capability in meeting the performance goals defined in Phase II development plan and the Navy requirements for effective hull-abrasion resistance performance. Concept performance will be demonstrated through prototype evaluation and modeling or analytical methods over the required range of parameters including numerous deployment cycles and field repairs. Evaluation results will be used to refine the prototype into an initial design that will meet Navy requirements. The company will prepare a cost benefit analysis as well as a Phase III development plan to transition the technology to Navy use.

PHASE III: Working with government and industry, the company will build full-scale add-on prototypes for protection of the bow keel, the upper hull shear and bow, and transom platforms or side shell corner protection and install the parts onboard a selected combatant craft. The company will conduct extended onboard operational testing to validate, certify, and qualify for Navy use. The small business will pursue global commercial markets in applying the new technology to commercial craft.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The developed technology will have direct applicability to over twenty boat builders who serve the U.S. military and commercial markets, as well as the international small boat commercial industry.

REFERENCES:
1. Military Craft and Boats, http://www.globalsecurity.org/military/systems/ship/boats.htm

2. Brian Hayman, Andreas Echtermeyer, Dag McGeorge "Use of Fibre Composites in Naval Ships", Det Norske Veritas AS, Hovik, Norway, 2001. http://research.dnv.com/euclid_rtp3.21/PW_Tools/PWE/Input/WARSHIP_2001_Hayman.pdf

3. Det Norske Veritas, Standard for Certification No.2.9 Type Approval Programme No.1-501.15, October 2009. https://exchange.dnv.com/Publishing/TAP/TAP415.pdf

4. ASTM Standard G190 - 06, "Standard Guide for Developing and Selecting Wear Tests" ASTM International, West Conshohocken, PA, DOI: 10.1520/G0190-06, http://www.astm.org/Standards/G190.htm

KEYWORDS: hull impact; abrasion resistance; beaching plate; expeditionary craft; combatant craft; small boats

** TOPIC AUTHOR (TPOC) **

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