Coffin was an engineering expert that Chief Engineer Geordi La Forge consulted in 2367. When it was discovered that a preburner was producing a richer deuterium flow, the two discussed what could be causing this issue. Mr. Coffin suggested that the issue could be one of pastore pulse overpressure. La Forge considered this to be a far more likely scenario than that proposed by one of his engineers, Ensign Stepan, who believed the issue to be one of thermal conductivity. (TNG: "Galaxy's Child")
For the remastered edition of "Galaxy's Child", the original Okudagram was replaced by a new graphic. Mr. Coffin was mentioned in that graphic.