N254-122 TITLE: Artificial Hardwood Replacement for Dry Docking Blocks

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials

OBJECTIVE: Develop a hardwood replacement compound for the blocks being used in dry docking ships. This loading is perpendicular to the wood grain and in compression only. Wood is used for its compliance under these forces. The replacement compound product does not need to look like wood or have a grain.

DESCRIPTION: Stakeholder Pearl Harbor Naval Shipyard and Intermediate Maintenance Facility needs a replacement for the hardwood caps on the docking blocks to continue the mission of repairing submarines and ships at their facility.

U.S. Navy docking blocks have changed very little in the past 100 years. These concrete blocks have a footprint of 42" x 48", and a total height of 48". The top and bottom of the concrete block are capped with 3ea 48" x 6" x 14" white oak timbers. See UFC 4-213-10, Figure 8-2 for the standard drawing [Ref 1]. These timbers are increasingly difficult to procure with long lead times. Additionally, these timbers are vulnerable to both termite and fungal attacks.

Larger dimension blocks, such as 12" x 12" x 48" are also in great need with a desire to use woodworking tools to cut the blocks into shape to conform to the shape of a ship’s hull.

This loading is perpendicular to the wood grain and in compression only. Wood is used for its compliance under these forces. The desired product does not need to look like wood or have a grain.

Capability Requirements/Performance Goals

A replacement compound for the hardwood caps would:

• Have the same or greater compressive strength when compared to white oak

• Have similar stress-strain characteristics to white oak

• Be nailable with similar or greater pullout strength to white oak

• Be able to withstand at least 330 LT for up to five years while remaining dimensionally stable

• Be immune to fungal and insect attack

• Be submersible without degradation

• Have the same or greater friction with concrete and steel without damaging the surface

• Be shapeable with woodworking tools

• Be nontoxic with nontoxic byproducts from cutting and forming

• Be price competitive to white oak

• Be produced in lead times under 30 days for up to 20k board-feet

In Japan, ESLON Neo Lumber FFU, a fiber reinforced foamed urethane product, has been used in this role, but this product is not available in the U.S. market and is cost prohibitive.

PHASE I: Identify potential materials and manufacturing processes that can be used to create materials that will meet the capability requirements and performance goals listed in the Description above. Conduct mechanical and chemical feasibility testing on samples. Develop a Phase II plan.

PHASE II: Based on Phase I results, further refine the material samples to meet the performance goals. Fabricate and validate the selected prototype series and mount the sample caps to a docking block for testing in a dry dock. Prepare documentation required for prototype testing and deliver prototypes to shipyard for demonstration and validation. The Navy will identify up to 6 blocks where the caps are ready to be replaced. These blocks will likely be located in dry docks in San Diego and/or Hawaii.

PHASE III DUAL USE APPLICATIONS: Upon demonstrating and validating the prototype cap samples for docking blocks in Phase II, the awardee will need to further prove the capability to create custom shapes and sizes beyond caps (i.e. side blocks) which have the same requirement and performance goals. Firm will scale up to provide 5,000 board-feet within a 30-day lead time with a plan to scale up to 20,000 board-feet within a 30-day lead time. Support the transition to use in Navy shipyards. Material with these properties would be useful in a number of industries. This would be an excellent substitute for hardwood used in marine fenders and railroad ties. As an idea of the amount of hardwood used, a typical destroyer dry dock block build uses 19,000 board-feet of hardwood. Current spending on hardwood caps at Pearl Harbor is about $750k per year. The DON’s spending on hardwood is likely similar at all four major shipyards: Norfolk Naval Shipyard (NNSY), Portsmouth Naval Shipyard (PNSY), Puget Sound Naval Shipyard and Intermediate Maintenance Facility (PSNS&IMF), and Pearl Harbor Naval Shipyard and Intermediate Maintenance Facility (PHNSY&IMF).

REFERENCES:

1. "UFC 4-213-10 UNIFIED FACILITIES CRITERIA (UFC) GRAVING DRY DOCKS." 18 May 2020. https://www.wbdg.org/FFC/DOD/UFC/ufc_4_213_10_2020.pdf
2. American Hardwood Export Council. "STRUCTURAL DESIGN IN AMERICAN HARDWOODS." 2005. https://www.americanhardwood.org/sites/default/files/publications/download/2017-04/AHEC%20Structural%20Guide.pdf
3. Western Wood Products Association. "PRODUCT USE MANUAL." June 2008. https://www.wwpa.org/resources/?id=western-lumber-product-use-manual

KEYWORDS: Material science; Artificial Hardwood; Dry docks; Wood Replacement; Lumber; Timber; Timber Replacement

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