Dredging Deeper Isn’t the Same as Competing Smarter
Mega-ships operate on multi-port service loops. They do not arrive, unload the full ship, and head back “from whence they came.” The taxpayer question is whether a 52-foot channel creates meaningful cargo diversion—or whether landside logistics and terminal productivity matter more.
What the U.S. Army Corps of Engineers Found
“The Charleston Harbor multiport analysis confirms the conclusions in the SHEP analysis that port deepening alone will not cause traffic to be diverted from or to other ports.”
“This conclusion is supported by the fact that there has been no discernible cargo diversion from other ports as a result of deepening the Port of Norfolk from 45 feet to 50 feet in 1988.”
“To the contrary, between 1998 and 2008, the Port of Savannah led all U.S. ports in TEU growth (258.1%), not because of its depth (43-foot), compared to Norfolk’s 50 feet, but because of its regional distribution centers, good rail connections, and the ability of the port to mix and match different types of cargo efficiently.”
The “Record Ship” Narrative vs. How Ships Actually Work
Charleston: “Largest ship to call our Port”
A Feb. 19, 2025 email circulated by SCPA leadership framed OOCL Iris as a milestone:
Subject: Timely Update
“Yesterday was a fantastic day as we celebrated the largest container ship to call our Port.”
“The OOCL Iris is beautiful and worked very smoothly.”
— Barbara L. Melvin, President & CEO, South Carolina Ports Authority
Savannah: same ship class, same “record” framing
Georgia Ports Authority likewise described OOCL Iris as the largest capacity vessel to ever call Savannah.
What competitive advantage does a 52-foot harbor depth truly provide if a major competitor, Savannah, with its 48-foot harbor, can handle the exact same “record” vessel class?
The taxpayer-friendly question is simple: why did South Carolina spend $580+ million to gain roughly four feet of depth over a major competitor when the “record-breaking” ship being celebrated reportedly arrived drawing about 38 feet—a draft Savannah can accommodate even at low tide?
These ships operate on scheduled loops. Each port typically exchanges partial batches—not full shiploads.
Service Loops: One Ship, Many Stops, Partial Batches
The graphic below is an original schematic to illustrate a simple point: a ship’s nameplate capacity (e.g., 16,000–18,000 TEU) is not what any one port unloads. Carriers call multiple ports and exchange containers in partial batches along the route.
How Much Cargo Does Charleston Typically Exchange Per Call?
SCPA board materials report the average number of container moves per vessel call—and show the distribution of calls by move-count class. This is the operational reality behind marketing headlines: most calls exchange far less than a ship’s nominal TEU capacity.
Primary Data: Vessel Calls and Drafts by Terminal
If you want to evaluate “depth” claims against real operations, start with vessel call and draft data by terminal. This dataset covers January 2022 through July 2025 and is labeled: “Vessel calls and drafts by terminal, January 2022 through July 2025.”
Vessel calls and drafts by terminal, Jan 2022–Jul 2025 (PDF) 5
Sources & Primary Documents
- U.S. Army Corps of Engineers, Charleston Harbor Deepening Project – Final EIS, Appendix C (Economics), “X. Summary and Conclusion,” p. 26. PDF
- South Carolina Ports Authority: Email regarding OOCL Iris vessel call (Feb. 19, 2025). PDF
- Georgia Ports Authority press release: “OOCL Iris becomes largest vessel to serve Savannah.” Link
- South Carolina Ports Authority, Board Materials: May 2022 “Berth Productivity – Overall.” Image
- Vessel calls and drafts by terminal, January 2022 through July 2025 (OCR PDF). PDF