Matt, my hunch about the rubber proved correct (and that explains the 20' tanks on deck in your last photo). She is loaded way too heavy to be carrying furniture, and it turns out she imports natural rubber. "Tapper" in her name refers to tapping trees for natural latex.
Processing and shipping
Natural rubber from Liberia is exported in two basic forms: latex concentrate and baled dry rubber.
After collection at the centralized storage tanks, ammonia is added to latex to deter it from coagulating (turning solid), and it is shipped by tank truck to the centrifuge operation at the factory in Harbel. Here it is checked again for its quality and characteristics. Latex which meets Firestone's control specifications is blended and fed into a battery of centrifuges where the actual concentration takes place. In these separators, excess water is removed and rubber content is increased from 30 percent to 60 percent.
Other rubber and field latex is processed into dried crumb rubber. The dried rubber is compacted into 75-pound bales and crated for shipment.
Both the latex concentrate and baled rubber are shipped from Harbel to Monrovia by Firestone trucks, where they are loaded aboard the “Harbel Cutlass” or the “Harbel Tapper." The ships, owned by Firestone, are designed specifically for trans-Atlantic rubber shipments. Each ship is equipped with latex tanks holding 1.2 million gallons of liquid latex. Dry cargo holds and containers on board hold dry rubber on the journey from Monrovia and on the return trips hold supplies used in rubber production.
Ships unload their cargo at three United States latex terminals – Savannah, Ga.; Baltimore, Md.; and Fall River, Mass. In addition the ships discharge dry block rubber at Norfolk, Va. From there it is distributed to customers across North America for manufacture.