An identical pair of WWI era U.S. Navy transports had two low smokestacks and three masts (one short one forward, a tall signal mast between the stacks, and another short one aft). Under construction for commercial employment between New York and Cuba, Orizaba and Siboney were taken over for Naval service when completed in the spring of 1918. Compared to other two-stack transports, they were of modest size. Only the hospital ships Comfort and Mercy (built a decade earlier for the same route) were smaller.
These ships' identical structural appearance is compounded, for identification purposes, by the very similar pattern camouflage they wore during 1918. To distinguish between them, it is essential to examine their photographs closely. If both were repainted overall grey (at present, we have only seen Orizaba in that color scheme), they may be even more difficult to tell apart during their later 1919 service.
This page features a table (with links to individual ships) of World War I era U.S. Navy transports with two smokestacks and three masts, plus one photograph of each ship in this group.
Click the small photographs to prompt a larger view of the same image with a descriptive header.
TWO SHIPS -- TWO SMOKESTACKS and THREE MASTS: