Band-Dependent Effects of Diesel and Electric Propulsion on Naval Infrared Signature Under Solar-Exposed and Solar-Free Conditions: A Full-Scale Sea-Trial Case Study

The choice between diesel and electric propulsion is an operational decision that requires no additional hardware, yet its effect on the infrared signature of a naval vessel has not been quantified in full-scale sea trials reported in the open literature. This case study compares the infrared radiation intensity of a single naval vessel under diesel and electric propulsion in the mid-wave (MWIR, 3–5 μm) and long-wave (LWIR, 8–12 μm) bands, under solar-exposed and solar-free conditions, with each measurement case recorded by a radiometrically calibrated system during a single continuous 0–360° turn. Under solar exposure, the diesel-to-electric ratio of median intensity was 1.31 in MWIR and 1.15 in LWIR, with a median angular reduction of 22–27% under electric propulsion; the LWIR result was more sensitive to the segmentation threshold than the MWIR result. Without solar exposure, the relationship persisted in MWIR (1.27) but reversed in LWIR (0.87). The solar-exposed and solar-free measurements differed in time of day and ambient conditions, and a sister vessel, measured only under solar exposure and under a different illumination geometry, showed the same overall direction but is used only qualitatively; the results are therefore specific to the observed acquisitions. The effect of propulsion configuration on radiation intensity depended jointly on spectral band and solar condition. Detection range and probability of detection were not assessed; the results nonetheless support further investigation of propulsion configuration as a potential operational variable in naval infrared signature management.