Cape Chalmers - Mooring Proposal.docx

CAPE CHALMER Alternative Anchoring Plan

Discussion

In March 2017, the Naval Facilities Engineering and Expeditionary Warfare Center (NAVFAC EXWC) was tasked by the United States Maritime Administration (MARAD) to design a backup Heavy Weather Mooring (HWM) system for the break bulk carrier Single-screw Steamship Cape Chalmers located alongside Pier Q at the Federal Law Enforcement Training Center (FLETC) in North Charleston, South Carolina. The NAVFAC Site Specific Report SSR-1726-OCN report produced in August 2017 recommended an engineered anchoring system that was estimated to cost approximately $2.3 million, which exceeds the budget for the project. The purpose of this document is to provide lower cost alternatives that provide a similar, albeit less robust anchoring system.

The NAVFAC proposal incorporates a four-point system of driven plate anchors to hold the ship in winds expected during a 57-knot wind event in order to meet the limitation of the mooring connections on the ship and provide a factor of 2.0 for the 3.5-inch chain to be used. The maximum force predicted for such winds is calculated by NAVFAC to be 104 kips of static load. A kip is a measure of force that converts to (0.44) long tons of force. The static load using this conversion equals 45.76 tons of force.

As an alternative to the driven plates, a combination of standard anchors and contract tugboats will be used to hold the ship in extreme wind and environmental conditions. The ship would be repositioned on the pier to provide the optimal scope of chain to the anchor and provide the best hold.

The JRRF would provide 3 shots of 2.75-inch stud link anchor chain and two 22,800-pound Navy Stockless anchors. The chain and anchors would be set by a commercial crane from a barge with JRRF for technical support. The anchor shall be placed at a slightly offset angle from the centerline of the ship to help prevent it from overriding the pier in a storm surge. The chains shall be made fast to the ship with pelican hooks to allow the chains to be slipped without crane support in case the ship needs to be moved in an emergency. The diagrams below show how the chains will be led onto the ship fore and aft, along with the securing points.

Bow Anchor

Stern Anchor

The overhead view blow shows the proposed locations of the anchors. The ship will need to be relocated on the pier as shown (the yellow outlines shows the current location of the ship).

Before and after anchors are deployed

Costs

The cost estimate for the project includes shipping the chain/anchors from the JRRF, commercial crane service in Charleston, and JRRF personnel travel. The anchors, chains, and hardware will be provided from stock on hand at the JRRF at no charge beyond shipping.

The table below shows the rough order of magnitude for each option and the padeye installation.

$31,000

Schedule

Assuming the work can begin on Sep 1, the following is a tentative schedule to complete the work.

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