John Ericsson developed the original design for the Casco class Monitors, but Chief Engineer, Alban C. Stimers (the General Inspector of Ironclads), “elaborated” on Ericsson’s design.
When bids were solicited for the ships, Assistant Secretary of the Navy, Gustavis Fox, wrote to Ericsson to confirm that Stimers had arranged the details with his approval. Ericsson replied that he had been kept in the dark, and that Stimers had ” frittered away” his principals. Regardless, Fox had begun to award contracts anyway. Twenty vessels were awarded contracts without serious checks of the Stimers’ altered design.
It was then discovered that Stimers had failed to compensate for the extra weight his design changes caused. This resulted in excess stress on the hull, resulting in a free-board of only 3 inches. Most of the class (except for the eight on slipways) was re-designed to compensate for the error, but they never achieved desired effectiveness as shallow draft ironclads.
Ericsson was called in to correct the problems with the vessels currently under construction. He raised the hulls of the first eight vessels including Casco and Chimo by nearly two feet. As a weight saving measure, he removed the turrets and added a single pivot mounted Dahlgren gun forward on a raised platform. Chimo, Casco, and the other six vessels were also fitted with torpedo spars, raised, armored pilot houses and were re-classified as Torpedo Boats.
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